UEENEEJ108A Recover, pressure test, evacuate, charge and leak test refrigerants Student Workbook

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CONTENTS CONTENTS RESOURCES AND REFERENCES INTRODUCTION SECTION 1 – INTRODUCTION TO REFRIGERANTS SECTION 2 - RELEVANT ACTS, REGULATIONS, CODES AND STANDARDS SECTION 3 – REFRIGERANT PROPERTIES SECTION 4 – SAFE HANDLING OF REFRIGERANTS SECTION 5 – REFRIGERATION OIL SECTION 6 - RECOVERY AND RECLAIM PROCEDURES SECTION 7 - PRESSURE TESTING SECTION 8 - LEAK DETECTION SECTION 9 - EVACUATION, DEHYDRATION SECTION 10 – REFRIGERANT AND OIL CHARGING SECTION 11 - SYSTEM CONTAMINATION

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Resources and references Recommended Text  



Boyle, G., Australian Refrigeration and Air Conditioning, 4th Edition, Volume 1 and 2, ISBN 186442.037.5, TAFE Publication of Western Australia, Perth, WA. Althouse, A.D., Turnquist, C.H., and Bracciano, A.F., Modern Refrigeration and Air Conditioning, 2nd Edition; ISBN 0 87006 196 8 The Goodheart –Wilcox Company Inc. Illinios, USA. Dossat, R.J., Principles of Refrigeration (SI Version), 2 nd Edition, ISBN 0.471.05271.X, John Wiley and Sons, Brisbane, Australia.

The following references are required reading for certain sections and are a prescribed text. Refer to the latest editions:  Refrigerant handling code of practice 2007: - Part 1, Self-contained low charge systems - Part 2, Systems other than self-contained low charge systems  AS/NZS1677 Parts 1 and 2 – Refrigerating systems.  Australian Institute of Refrigeration, Air Conditioning and Heating (Inc.), The Refrigerant Selection Guide, ISBN 0 949436 34 8 AIRAH, Australia.

Australian Standards and Codes of Practice For the following standards, refer to the latest editions:  AS1216 – Class labels for dangerous goods  AS2030 – The verification, filling, inspection, testing and maintenance of cylinders for storage and transport of compressed gases  AS2700 – Colour Standards for general purposes  AS4211 – Gas recovery or combined recovery and recycling equipment  AS4484 – Industrial, medical and refrigerants compressed gas cylinder identification  NOHSC 2012 – National Code of Practice for labelling of workplace substances  Boiler and Pressure Vessels Regulations, and relevant codes

Websites Web references have been included in the text where appropriate, and indicate where materials have been sourced. Webpages containing information for this topic can be found at: http://hvaceducation.wikispaces.com/UEENEEJ008B http://www.hvaceducationaustralia.com

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Introduction UEENEEJ108A: This unit covers recovery, pressure testing, evacuating, charging and leak testing recovery of refrigerants and lubricants from refrigeration systems and air conditioning systems. It encompasses working safely and to standards, following regulations and industry practices for handling refrigerants and lubricants, and completing the necessary documentation. This resource manual contains learning material, review questions and assessment events. It is designed to assist students achieve the performance outcomes described in the national Competency standard unit UEENEEJ108A - Recover, pressure and leak test, evacuate and charge refrigerants and is an example of the depth and breadth of expected learning. This student workbook covers the basic knowledge needed to recover refrigerant from a system, pressure and leak test the system, evacuate the system and finally charge the system with a quantity of refrigerant. The entire unit UEENEEJ108A contains the essential elements of the CFC Authorisation / Licensing Regulations embodied in the Ozone Protection and Greenhouse Gas Management Act 1989, and regulations. They apply to usage, reclaim, evacuation, and disposal of refrigerants, and includes the understanding and application of the Refrigerant Handling Code of Practice 2007 and relevant Australian Standards. Important note: You are required by law to comply with the Acts and Codes governing the refrigeration industry once you have covered the required knowledge. This booklet follows the Essential Knowledge and Skills (EKAS) as defined in the unit descriptor for UEENEEJ108A: KS01-EJ108A Refrigerants and lubricants

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Section 1 – Introduction to refrigerants Introduction – T1 This section is the introduction to refrigerants and includes the following topics:  Purpose of refrigerant  Primary, secondary and expendable refrigerants  Ideal properties  

Pure, azeotropic, zeotropic and blend refrigerants General safety requirements and personal protection equipment

Purpose of a refrigerant

A refrigerant is a compound that can readily absorb heat at one temperature, then compressed by a heat pump to a higher temperature and pressure where it changes phase and discharges the absorbed heat. (http://chemistry.about.com/od/chemistryglossary/g/Refrigerant-Definition.htm)

The refrigerant Handling Code of Practice 2007 Part 2 defines refrigerant as: The medium used for heat transfer in a refrigerating system, which absorbs heat on evaporating at a low temperature and a low pressure and rejects heat on condensing at a higher temperature and higher pressure. The refrigerant used in refrigeration systems absorbs heat in the evaporator, (changing state from a liquid to a vapour by using the heat in the space), and rejects this absorbed heat in the condenser as it changes from a superheated vapour back to a liquid.

Classes of Refrigerant Refrigerants can be classed as primary, secondary or expendable refrigerants. Primary refrigerants: are substances that change state twice (once in the evaporator and once in the condenser). Primary refrigerants transfer the bulk of the heat through a latent heat process, and are used in refrigeration systems such as vapour compression and absorption refrigeration systems. Secondary refrigerants: absorb heat and change temperature in order to transfer heat from the substance / product to be cooled. They usually do not change state in the cooling cycle but change temperature by absorbing sensible heat. A typical example of a secondary refrigerant is chilled water and glycol solutions.

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Secondary refrigerants used in any indirect system in any occupancy shall have either— (a) no flash point; or (b) a flash point higher than 65°C. (AS/NZS 1677.2:1998)

Expendable refrigerants: change state once and are lost to the environment through vaporisation, sublimation or melting. Common examples of expendable refrigerants are: Product Boiling Temp Liquid nitrogen –196°C Dry ice [solid CO2] –79°C Ice (water) 0°C *Temperatures are at atmospheric pressure.

Process (vaporisation) (sublimation) (melting)

Properties of Ideal Refrigerants: All refrigerants have different properties, and an "Ideal" refrigerant would have the all the good characteristics and properties and none of the bad. Unfortunately no single refrigerant can offer this, and so each refrigeration or air conditioning system will use a refrigerant that best suits its requirements. Desirable refrigerant characteristics can be summarised as follows: 1) The refrigerant should have low boiling point and low freezing point. 2) It must have low specific heat and high latent heat. Because high specific heat decreases the refrigerating effect per kg of refrigerant and high latent heat at low temperature increases the refrigerating effect per kg of refrigerant. 3) The pressures required to be maintained in the evaporator and condenser should be low enough to reduce the material cost and must be positive to avoid leakage of air into the system. 4) It must have high critical pressure and temperature to avoid large power requirements. 5) It should have low specific volume to reduce the size of the compressor. 6) It must have high thermal conductivity to reduce the area of heat transfer in evaporator and condenser. 7) It should be non-flammable, non-explosive, non-toxic and non-corrosive. 8) It should not have any bad effects on the stored material or food, when any leak develops in the system. 9) It must have high miscibility with lubricating oil and it should not have reacting properly with lubricating oil in the temperature range of the system. 10) It should give high COP in the working temperature range. This is necessary to reduce the running cost of the system. 11) It must be readily available and inexpensive. Download from: http://nptel.iitm.ac.in/courses/IITMADRAS/Applied_Thermodynamics/Module_6/12_Required_Properties_of_Idea_Refrigerants.pdf

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Pure, azeotropic, zeotropic and blend refrigerants Primary refrigerant types - All primary refrigerants fall into one of the three basic types, as explained below: Pure: Consists of one chemical compound. Examples of pure refrigerants include: R134a (Tetrafluoroethane), R22 (Chlorodifluoromethane), and R123 (Dichlorotrifluoroethane). Azeotropic: Consists of a mixture of two or more chemical compounds which in the case of refrigerants are volatile substances. Azeotropic refrigerants are characterised by: remaining in the same proportions throughout the refrigeration cycle boiling at a constant temperature as the mixture evaporates. Examples include the R500 family, R500, R502, R503, R507, R508A, R508B, and R509A. Zeotropic (or near–azeotropic): Consists of a mixture of two or more chemical compounds, (known as Blends) that are volatile substances that change in composition as it evaporates. Consequently, the evaporating temperature changes (known as glide) as the more volatile component distils out of the less volatile components (fractionates). Examples include the R400 family, R401A, R404A etc. Two basic types of zeotrope exist; they are Binary and Ternary Blends. Binary blends consist of a mixture of two pure refrigerants; ternary blends consist of a mixture of three pure refrigerants. R400 series refrigerants must be charged into a system as a liquid.

General safety requirements and personal protection equipment Refrigerants present a wide variety of health and safety risks to the user and the environment. Accidental release and loss of refrigerant is becoming expensive, is harmful to the environment, (global warming and ozone depletion), and presents significant health risks to the individual from refrigerant burns to asphyxiation. Users must be aware of the risks associated with storing, handling and using refrigerants. Personal protective equipment is an essential part of user safety including gloves, safety glasses, face shield (where appropriate), and long sleeve shirt and pants. Detailed safety procedures for handling and using refrigerants, including the harmful effects of refrigerants and cylinder safety, is covered in section T4 of this booklet. End of Section

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Section 2 - Relevant Acts, Regulations, Codes and Standards Introduction - T2 This section is the introduction to acts, regulations, codes and standards, and includes the following topics:  The ozone layer (function, ozone depleting substances)     

The ozone protection act and regulation State and federal agencies (Dept. of the environment, water, heritage and the arts; Dept. of climate change; Australian Refrigeration Council Ltd etc.) State and federal licensing requirements Refrigerant handling code of practice 2007 Relevant Standards

  

Standards philosophy and format How to read and apply a standard Equipment manufactures specifications

The ozone layer (function, ozone depleting substances) The function of the ozone layer UV radiation is part of the electromagnetic (light) spectrum that reaches the earth from the sun.

Downloaded from http://drdima.files.wordpress.com/2009/05/sun-rays.jpg

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There are 3 different types of UV radiation:  UVA, B and C. 

UVC is the strongest wavelength but is also the shortest and usually gets absorbed by the ozone layer before it reaches the earth.

  

UVB is responsible for most burns. UVA (UVAI and UVAII) is the least intense, but the most deeply penetrating. UVA and UVB can cause premature skin aging, eye damage (i.e. cataracts) and skin cancer.

95% of all UV rays are UVA.

UVB rays intensity varies by season, location and time of day.

UVA rays are relatively constant all day, every day, and can penetrate through clouds and glass. Yes, there are UV rays on rainy, cloudy days even though you can‘t see them. Wear your sunscreen!!

They can burn you all year round especially around snow and ice since 80% of rays are reflected back at you and you are hit by them twice.

http://mypage.iammodern.com/profiles/blogs/what-is-uv-radiation

http://www.anthelios.com/images/uv_skinLayer.jpg

What is the ozone layer? Ozone is a naturally occurring molecule containing three atoms of oxygen. Ozone molecules form a gaseous layer, mostly in the upper atmosphere, (the stratosphere) 15-30 km above the surface of the earth. Ozone is produced by the effects of UV light

The stratospheric ozone layer protects life on Earth by absorbing ultra-violet (UV) radiation from the sun. UV radiation is linked to skin cancer, genetic damage and immune system suppression in living organisms, and reduced productivity in agricultural crops and the food chain.

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Effects of ozone depleting substances All refrigerants break down when they reach the stratosphere due to the effects of radiation, especially UVB. Refrigerants containing chlorine atoms breakdown releasing chloride ions and this free chloride acts as a catalyst thereby breaking down the ozone. The greater the breakdown of the ozone layer, the more UVB reaching the Earth‘s surface, and the more UVB, the greater the biological damage.

http://www2.umaine.edu/USITASE/images/teachers/figures/fig1b.jpg

Alternative refrigerants – removing the chlorine from refrigerants Australia is a signature to the Montreal and Kyoto Protocol, which sets out a time frame for the phase out of ozone depleting substances. Alternative refrigerants are being developed that are environmentally friendly with low or no ozone depletion and lower greenhouse warming potential.

New generation Ozone friendly refrigerants – High capacity, high pressure refrigerants Higher system pressures mean that the system equipment, tools and containers for these refrigerants (i.e. R410A) have to be designed for much higher pressure ratings. The equipment that must be capable of withstanding these higher pressure ratings includes:      

Shipping containers Cylinders Storage tanks Tank trailers Refrigeration and air conditioning equipment, including the copper tubing. Service tools – i.e. gauges, manifolds and gauge lines.

Danger! Do not modify existing fittings to suit R410A – only use equipment rated for R410A use.

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Ozone Protection Act and regulations In June 2005 the Australian Refrigeration Council (ARC) was appointed by the Minister for the Environment and Water Resources to administer the refrigeration and air conditioning aspects of the Regulations. On the 1st of July 2005, the Australian Government implemented a licensing scheme to support regulations under the Ozone Protection and Synthetic Greenhouse Gas Management Act 1989, designed to reduce emissions of environmentally harmful refrigerant gases. The ARC is responsible for granting refrigerant handling licences and refrigerant trading authorisations approved under the Regulations.

State and federal agencies – Dept. of the environment, water, heritage and the arts; Dept. of climate change; Australian Refrigeration Council Ltd etc.) . Various state and territory governments may have legislation that applies to the refrigeration industry. Students must check the website of their respective state or territory government for more information about which rules may apply to the type of work they carry out. Federal organisations responsible for refrigerant legislation includes: Department of Sustainability, Environment, Water, Population and Communities The department is responsible for implementing the Australian Government's policies to protect our environment and heritage, and to promote a sustainable way of life. One of their key responsibilities is ‗Atmosphere‘ including Ozone and Greenhouse protection. Under the Australian Government's Clean Energy Future Plan, synthetic greenhouse gases listed under the Kyoto Protocol - hydrofluorocarbons, perfluorocarbons (excluding gases produced from aluminium smelting) and sulphur hexafluoride, and any equipment or products which contain these gases - will have an equivalent carbon price applied through the existing Ozone Protection and Synthetic Greenhouse Gas Management legislation. For more information, go to their website: http://www.environment.gov.au/index.html Australian Refrigeration Council (ARC): The Australian Refrigeration Council Ltd (http://www.arctick.org/index.php) administers refrigerant handling licences and refrigerant trading authorisations on behalf of the Australian Government, to professionals in the refrigeration/air conditioning and auto industry.

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State and federal licensing requirements Under the Ozone and Synthetic Gas Management Regulations 1995 (‗the Regulations‘), a Refrigerant Trading Authorisation is required when a business or individual wishes to acquire, possess or dispose of refrigerant. A Refrigerant Trading Authorisation is subject to conditions and auditing processes designed to minimise the risk of emissions while the refrigerant is in the business or individual‘s possession. Anyone wanting to install, service or repair an air conditioner, or any other piece of refrigeration and air conditioning equipment must be a licensed technician under the regulations. The holder of a Refrigerant Handling Licence is an individual who is qualified in their field of activity and has met the licensing requirements under the regulations. The Arctic website has more information on licensing at: http://www.arctick.org/index.php State licensing for the operation of a refrigeration or air conditioning business varies in each state. Some common licenses required to operate a business are as follows:  Restricted electrical licence  Building Service Authority License (QLD)  Office of Fair Trading Licence (NSW) Queensland Hydrocarbon Licence: Under the Petroleum and Gas (Production and Safety) Act 2004 a person who installs, commissions and services domestic and commercial refrigeration units along with split system and other air conditioners must be the holder of a gas work licence (hydrocarbon refrigerants). A device that uses hydrocarbon refrigerants is a Type B gas device and is required to be approved before it is sold, installed or used. An appliance such as a refrigerator or an air conditioner that uses hydrocarbon refrigerants e.g. R600, must be approved by a recognised Type B approving authority (PDF, 14 kB) or the Chief Inspector Petroleum and Gas, before it is sold, installed or used in Queensland. Anyone installing, removing, altering, repairing, servicing, testing or certifying the gas system of a device (i.e. charging, discharging or breaking into the refrigeration system that uses hydrocarbon refrigerants) must hold a Gas Work Licence (Hydrocarbon Refrigerants) to do so.

Refrigerant handling code of practice 2007 Two major environmental issues have affected work practices in the refrigeration and air conditioning industry, they are: 

ozone depletion



global warming

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Ozone depletion and global warming can be minimised by effective emission controls, avoiding all deliberate losses and minimising unavoidable losses of refrigerants. The primary objective of the refrigerant handling Code of Practice is to reduce the emissions of refrigerants into the atmosphere, and to so reduce ozone depletion and global warming. It achieves this by outlining the minimum acceptable standards for work practices in the industry. People working in the refrigeration industry must do everything possible to reduce the emission of substances to the atmosphere. You can do this by adhering to good work practices and be conscious of the long term effects of our actions. Compliance with these Codes of Practice is a mandatory requirement under the Ozone Protection and Synthetic Greenhouse Gases Act (OP & SGG) and its regulations put in place by the Commonwealth government of Australia. The Australian and New Zealand Refrigerant Handling Code of Practice 2007 has been produced in two parts, as outlined below: Part 1 – Self-contained low charge systems This code applies only to appliances which contain a fluorocarbon refrigerant charge of two kilograms or less, and do not require any work to be done on the refrigeration system at the time of installation. Part 2 – Systems other than self-contained low charge systems This code applies to all refrigeration and air conditioning systems which use fluorocarbon refrigerants, including heat pumps and transport refrigeration and air conditioning systems (excluding self-contained low charge systems).

Relevant Standards philosophy and format How to read and apply a standard What is a Standard? Standards are published documents setting out specifications and procedures designed to ensure products, services and systems are safe, reliable and consistently perform the way they were intended to. They establish a common language which defines quality and safety criteria. http://www.standards.org.au/StandardsDevelopment/What_is_a_Standard/Pages/default.aspx

Australian standards relevant to the handling of refrigerants include:  AS1677.1:1998 Refrigerating Systems. Part 1 Refrigerant classification  AS1677.2:1998 Refrigerating Systems. Part 2 Safety requirements for fixed applications Standards are developed to strict guidelines of content and conformity. More information about Australian standards can be found at: http://www.standards.org.au . The content and structure of a standard is as follows:

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Title page The title page shall indicate, without ambiguity, the subject matter of the document in such a way as to distinguish it from that of other documents, without going into unnecessary detail. The title shall be composed of separate elements, each as short as possible, proceeding from the general to the particular. In general, not more than the following three elements shall be used: (a) An introductory element (optional) indicating the general field to which the document belongs (this can often be based on the title of the committee which prepared the document). (b) A main element (obligatory) indicating the principal subject treated within that general field. (c) A complementary element (optional) indicating the particular aspect of the principal subject or giving details that distinguish the document from other documents, or other parts of the same document. Preface It consists of a general part and a specific part. The general part gives information relating to whether the document is a joint Australian/New Zealand or Australian Standard and the designation and name of the committee that prepared the document. The specific part shall give as many of the following as are appropriate: (a) A statement that the document cancels and replaces other documents in whole or in part. (b) The relationship of the document to other documents (see 5.2.1, last paragraph). (c) The objective of the document, if there is no objective clause (see 6.2.2). (d) Origin of content of the document, e.g. IEC, ISO, other national Standard or work by a recognised body, and whet her it is identical, modified or not equivalent. (e) Principal differences between the new and old edition.

Table of contents The table of contents shall be entitled ―Contents‖ and shall list sections, clauses, appendices together with their status in parentheses, the bibliography, and indexes.

Foreword The Foreword is an optional preliminary element used, if required, to give specific information or commentary about the technical content of the document, and about the reasons prompting its preparation.

Scope This element shall appear at the beginning of each document and define without ambiguity the subject of the document and the aspects covered, thereby indicating the limits of applicability of the document or particular parts of it. The scope shall be succinct so that it can be used as a summary for bibliographic purposes.

Objective The objective of the document states the purpose that the document is intended to serve. The objective statement shall be located either as a paragraph in the Preface or in a dedicated ―Objective‖ clause immediately following the Scope clause.

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Application The application clause is an optional element and is only required in those situations where the reader may be unclear as to how to apply the document .The application clause provides information about how the document is intended to be used.

List of referenced documents This optional element shall give a list of the normative referenced documents cited in the document. Such referenced documents may be listed in an informative appendix or a bibliography.

Definitions This is an optional element giving definitions necessary for the understanding of certain terms used in the document.

Headings The content of the standard is arranged under headings, and sub-sections. The content must follow strict rules of structure and grammar. For more information visit the Australian Standards http://www.standards.org.au/StandardsDevelopment/Developing_Standards/Documents/SG006%20Rules%20for%20the%20Structure%20and%20Drafting%20of%20Australian%20Standards.pdf

Equipment manufacturers specifications Technical manuals provide the necessary information for the service technician to carry out service and repair and include the following information:  Technical specifications for each model including – capacity in kW of heating and cooling, power consumption, current draw, interconnecting pipe sizes, compressor type, unit size and weight, airflow, refrigerant type and other information.  Electrical circuit diagrams – wiring or schematic.  Disassembly illustration or exploded view – indicate where is part or item is located, and 

Parts list – list of all the parts including the identification number.

The type and weight of refrigerant and the type of oil used are critical to achieve the required cooling capacity, and prolong the life of the equipment. Manufacturer‘s installation instructions are a useful guide to the correct installation of a unit, however, they must not specify a practice that contravenes a clause of the Refrigerant Handling Code of Practice 2007, or other Australian code, standard or legislation. The provisions in this code, however, take precedence over any original equipment manufacturer instructions (except where specified otherwise herein). (Australia and New Zealand refrigerant handling code of practice 2007 • Part 2 page 8 — Systems other than self-contained low charge systems)

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The manufacturer of mass produced and ‗made to order‘ refrigeration and air conditioning equipment provide technical and installation manuals for each model and type of equipment.

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Section 3 – Refrigerant Properties Introduction - T3 This section is the introduction to refrigerant properties, and includes the following topics:  Commonly used types, including CFC, HCFC, HFC, high pressure and natural refrigerants  Terms (blend, azeotrope, zeotrope, glide, CFC, HCFC, HFC, HC, bubble point, dew point, critical point, ODP, GWP etc.)  Typical properties and applications of the current refrigerants used in systems (boiling point, glide, composition (components), comparative latent heat

Commonly used types, including CFC, HCFC, HFC, high pressure and natural refrigerants Refrigerants are identified by a number preceded by an ‗R‘, and are sometimes referred to by a trade name, e.g. Care 10 (R600a), Isceon 49 (R437A). The common groups of refrigerants can be classified according to their chemical composition:  CFC: Fully-halogenated (no hydrogen remaining) halocarbon containing chlorine, fluorine and carbon  HCFC: Halocarbon containing hydrogen, chlorine, fluorine and carbon  HFC: Halocarbon containing only hydrogen, fluorine and carbon  PFC: Perfluorinated carbon containing only fluorine and carbon  HC: Hydrocarbon containing only hydrogen and carbon R290 and R600a  Natural: Carbon dioxide (CO2 or R744) and Ammonia (R717) *This is not a complete list of refrigerants

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Terms (blend, azeotrope, zeotrope, glide, CFC, HCFC, HFC, HC, bubble point, dew point, critical point, ODP, GWP etc.) There are many terms and abbreviations used in the refrigeration industry. Below are some of the more common abbreviations and terms associated with refrigerants taken from AS/NZS1677.1 - 1998 General Terms Abbreviation AEL EEL GWP ODS ODP TEWI

Meaning Acceptable (allowable) Exposure Limit Emergency Exposure Limit Greenhouse (Global) Warming Potential Ozone Depleting Substance Ozone Depletion Potential Total Equivalent Warming Impact

Blends A combination of two or more in a defined ratio which forms a specified thermodynamic properties. (RH COP 2007 Part 2).

with

Pure Refrigerants Pure: Consists of one chemical compound. Examples of pure refrigerants include: R134a (Tetrafluoroethane), R22 (Chlorodifluoromethane), and R123 (Dichlorotrifluoroethane).

Azeotropes 1.3.1 Azeotrope A mixture of volatile substances which is characterized by remaining in the same proportions and boiling at a constant temperature as the mixture evaporates. NOTE: The azeotropic proportions for a particular azeotrope apply strictly at a specific pressure but in practice azeotropic mixtures appear to evaporate and condense as if they were a single fluid, with properties different from their components, over a range of pressures.

Single-component refrigerants (pure) and azeotropes boil and condense at one temperature for a given pressure. Therefore, only one column is needed to show the pressuretemperature relationship for any phase-change process in a system (see Figure 1).

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Figure 1 http://www.refrigerants.com/chart.htm

Zeotropes 1.3.14 Zeotrope (non-azeotrope) A mixture of volatile substances which changes in composition as it evaporates. As a consequence, the evaporating temperature changes as the more volatile component distils out of the less volatile component(s). AS1677.1 - 1998 The properties of the new zeotropic blends are somewhat different than the traditional refrigerants. Zeotropic blends shift in composition during the boiling or condensing process (see Figure 2). As the blend changes phase, more of one component will transfer to the other phase faster than the rest.

Figure 2 http://www.refrigerants.com/chart.htm

This property is called fractionation. The changing composition of the liquid causes the boiling point temperature to shift as well. The overall shift of temperature from one side of the heat exchanger to the other is called the temperature glide.

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UEENEEJ108A Recover, pressure test, evacuate, charge and leak test refrigerants Zeotropic blends cannot be defined by a single pressure-temperature relationship. The temperature glide will cause different values for temperature at a given pressure, depending on how much refrigerant is liquid and how much is vapour. The most important values for checking superheat and sub-cool are the end points of the glide or the pressuretemperature relationship for saturated liquid and saturated vapour. The saturated liquid condition is often referred to as the bubble point. Imagine a pot of liquid sitting on a stove; as it begins to boil it forms bubbles in the liquid. The saturated vapour condition is referred to as the dew point. Imagine a room full of vapour (like in a sauna), and dew drops forming on the furniture. PT charts for the zeotropic blends list two columns next to each temperature: one for the saturated liquid (bubble point) and the other for the saturated vapour (dew point).

Typical Bubble and dew points are shown on the R407C pressure enthalpy chart:

http://www.sciencedirect.com/science/article/pii/S0140700703001701

Critical temperature (point)

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UEENEEJ108A Recover, pressure test, evacuate, charge and leak test refrigerants The highest temperature the refrigerant can have and still be condensable by the application of pressure is the ‗critical point‘ (Pc). When above the critical temperature all liquid refrigerant within a system will revert to a vapour. (Corresponds to the uppermost part of the saturated liquid/vapour curve on the pressure enthalpy chart).

Typical properties and applications of the current refrigerants used in systems (boiling point, glide, composition (components), comparative latent heat

End of Section

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Section 4 – Safe Handling of Refrigerants Introduction - T4 This section is the introduction to the safe handling of refrigerants, and includes the following topics:         

Refrigerant identification and the numbering system (AS 1677 part 1 sect 3) System refrigerant identification (labelling requirements, Code of Practice) Typical hazards (classification groups - AS 1677 part 1 sect 2 and handling precautions - inhalation, skin contact, cardiac sensitization, decomposition, reaction with moisture etc.) Personal safety (MSDS - all common refrigerants plus phosgene, recommended PPE) Cylinders (cylinder terminology (WC, tare etc.), transporting safely) Safe Filling (density and water capacity methods) Decanting methods (pumping, temperature differential etc.) Recovery cylinders and their safe filling. Disposal of recovered refrigerants (including RRA)

Refrigerant identification and numbering systems There are several methods of identifying refrigerant types used in systems or stored in cylinders. You will need to be aware of these methods as you could ―cocktail‖ the refrigerant charge in a system or cylinder, which can have disastrous effects on a systems operation. ―Cocktailing‖ means mixing refrigerants which are not meant to be mixed together, in one container. Refrigerant numbering system (ARAC Volume 1, Chapter 1 and AS 1677.1) Du Pont (developers of Freon refrigerants) devised a refrigeration numbering system in 1956 and this same numbering system is still in use today. It allows us to identify each refrigerant type available in the industry. AS/NZS1677.1, Part 1, Section 3 provides an in depth description.

System Refrigerant identification system As well as a numbering system for the various refrigerants, a colour code for refrigerant cylinders has been devised. Various Australian Standards specify the colour coding for cylinders containing refrigerants, or refrigerant combinations. Examples of these codes include:  

AS4484 – Industrial, medical and refrigerants compressed gas cylinder identification AS2030 – The verification, filling, inspection, testing and maintenance of cylinders for storage and transport of compressed gases.  AS2700 – Colour Standards for general purposes Listed below are some of the refrigerants in common use today:

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Refrigerant Number

Refrigerant Name

Type

Chemical Formula

Band Colour

R717

Ammonia

Natural

NH3

Slate

R22

Chlorodifluoromethane

HCFC

CHClF2

Moss Green

R404a

R125 + 143a + R134a 44% 52% 4%

HFC

Ternary Blend of HFC refrigerants

Orange

R134a

Tetrafluoroethane

HFC

CF3CH2F

Light Blue

R410A

R125 + R32 50% 50%

HFC

Binary Blend of HFC refrigerants

Rose

Many of the traditional refrigerants are being phased out due to their ozone depleting capability. During the transitional period, care must be taken when colour coding is used as a sole means of identification. Some systems / applications utilise the chemical symbol and refrigerant number together to eliminate doubt about the refrigerant type used in a system.

Typical hazards (classification groups - AS 1677 part 1 sect 2 and handling precautions - inhalation, skin contact, cardiac sensitization, decomposition, reaction with moisture etc.) Generally, all refrigerants are:  considered to be either asphyxiating or toxic to some degree and some refrigerants are flammable, such as R717, R290 and R600 (some more than others).  heavier than air and will settle at ground level.  extremely volatile, boiling at very low temperatures, from +24°C to –50°C and lower.  stored in cylinders that are classified as pressure vessels by AS 2030, except refrigerants like R11 and R123. Refrigerant burns Spillage of liquid refrigerants, such as R22 and R134a, will cause frostbite (freeze / thermal burn) to occur on any unprotected parts of our body, due to the low boiling point of these refrigerants. In the event of frostbite, do not remove clothing from affected area. Frostbite should be treated by: 1. placing the affected limb in lukewarm water for 10 to 15 minutes depending on depth of burn then 2. covering the affected limb with a burn cream and then transporting the patient to hospital.

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UEENEEJ108A Recover, pressure test, evacuate, charge and leak test refrigerants Spillage of liquid refrigerants, such as R11 and R123, will cause dryness, de–oiling, cracking and possible dermatitis to any unprotected parts of the body. These refrigerants have higher boiling point than other refrigerants. Inhalation of refrigerant vapour Refrigerant vapours are denser than air and may reduce the available oxygen. The symptoms likely to be experienced upon inhalation of refrigerant vapour include narcosis, anaesthesia, respiratory depression, unconsciousness and possible asphyxiation. In addition, inhalation may lead to cardiac arrhythmia in susceptible individuals due to cardiac sensitisation, which can be suddenly fatal. In the event of cardiac arrhythmia or if the victim is overcome with refrigerant vapour inhalation, move the victim to fresh air and rest in a half upright position, loosening their clothing. Give oxygen or artificial respiration if there is any difficulty in breathing. Apply external cardiac massage in case of cardiac arrest. Advise the doctor of the refrigerant type. Ensure first aid procedures have been carried out, treating symptomatically and avoiding the use of adrenalin. Cardiac arrhythmia may also occur if drugs such as adrenalins are given (see Appendix 3 – Material Safety Data Sheets). Refrigerant and an open flame All commercially available fluorinated hydrocarbon refrigerants are non-flammable and nonexplosive, an extremely important safety feature. These refrigerants will decompose however if subjected to sufficiently high temperatures. Over 540ºC is required for decomposition and since the average flame temperature of oxy-acetylene torch is higher, decomposition may occur. It should be noted that the heat would only affect the refrigerant vapour that actually passes through the flame. When fluorinated hydrocarbon refrigerants are decomposed by high temperature they form hydrogen chloride, hydrogen fluoride and small quantities of other gases, which may cause ill effects if inhaled in sufficient quantities. Generally, the pungent odour of these products gives ample warning of their presence. Most materials such as soldering flux, oil, dirt and all refrigerants decompose at the temperatures used in soldering. Therefore, the area in which repair is carried out should be properly ventilated to remove the products of decomposition and combustion. An adequately ventilated work area is good practice at any time but especially when an open flame of a leak detector or welding torch is to be used in the presence of ‗fluorocarbon‘ refrigerants. Those halogenated fluorocarbon refrigerants containing chlorine decompose to form phosgene (COCl2), which is very toxic but unstable (decomposes quickly). Because of this, it decomposes to form halogen acids such as hydrofluoric and hydrochloric acids (HF and HCl). It has a very pungent odour to warn of its presence. (Halogenated refrigerant + heat + moisture ––> phosgene ––––> acids)

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Section 5 – Refrigeration oil Introduction - T5 This section is the introduction refrigeration oil, and includes the following topics:     

Types (mineral, POE, AB etc.) and their applications Basic properties (miscibility, dielectric strength, viscosity and hygroscopic abilities) Typical issues regarding compatibility (neoprene and POE, POE and mineral etc. Safe handling (MSDS - POE's, Mineral, AB's - Residual acid's in used oils Applications for the various compressor lubricants used in the trade

Types and applications Refrigeration compressor lubricants consist of two major types: mineral oils and synthetics such as alkylbenzenes (AB), polyol esters (POEs) and polyalkylene glycols (PAGs). Mineral oils have been used for many years with ammonia, CFC and HCFC refrigerants. POEs and PAGs need to be used with HFC refrigerants; synthetic refrigeration lubricants. Both POEs and PAGs are highly hygroscopic (affinity for moisture). Of the two, PAGs are substantially more hygroscopic than POEs. You must take great care to minimize exposure to the atmosphere in both cases. POEs (polyol esters) - are used with HFCs to serve most industrial, commercial and residential air-conditioning and refrigeration systems. PAG (Polyalkylene Glycol) Oil - primary lubricant used for automotive air conditioners. AB (Alkylbenzene) - is a synthetic oil derived from alkylated benzene. It is similar in many ways to mineral oil and has some superior properties that make it particularly valuable in ultra-low temperature refrigeration and air-conditioning applications. Some major compressor manufacturers prefer alkyl benzene refrigeration oil for some applications with HCFC refrigerant blends such as R-22, R-123 and R-401A. However, alkylbenzene refrigeration oil with the proper viscosity can be used with most CFC and HCFC refrigerants as well as hydrocarbons and ammonia in most refrigeration and air-conditioning applications.

Basic properties (miscibility, dielectric strength, viscosity and hygroscopic abilities)

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UEENEEJ108A Recover, pressure test, evacuate, charge and leak test refrigerants  



Good miscibility and solubility - to assist in good oil return to the compressor, where it belongs Chemical Stability - to resist chemical reaction with the refrigerant or other material normally present in the system. Thermal Stability - to eliminate excessive carbon deposits at compressor hot spots such as valves or discharge portsLow Wax Content - to prevent separation of flocculant wax from the oil-refrigerant mixture at the low temperature points in the systemLow Pour Point - to prevent separated oil from congealing in refrigerant lines.High Dielectric Strength - to ensure good insulating properties. In hermetic units, the oil-refrigerant mixture serves as an insulator between the motor and the compressor body.Proper Viscosity - even when diluted with refrigerant so as to insure high film strength at elevated operating temperatures and while providing good fluidity under coldest operating conditionsNo Contamination - to prevent scarring of bearing surfaces, plugging of lines and general deterioration.http://www.sunoco.co.jp/english/product/gs/index.html

Typical issues regarding compatibility (neoprene and POE, POE and mineral etc.

Safe handling (MSDS - POE's, Mineral, AB's - Residual acid's in used oils

Applications for the various compressor lubricants used in the trade

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Section 6 - Recovery and Reclaim Procedures Introduction - T6 This section is the introduction to the recovery and reclaim procedures, and includes the following topics:      

Refrigerant recovery systems and procedures Vapour Liquid Recovery cylinders Disposing of recovered refrigerants Safety and general issues when recovering refrigerant

Refrigerant recovery systems and Procedures All chemically manufactured or synthetic greenhouse gas (SGG) refrigerants must be recovered at all times from a system. This can be done through either pump down or recovery. Purging to remove air, moisture or other contaminates is unacceptable under the Ozone Protection Act and Regulations and the Australian Standards along with their associated handbooks such as the Refrigerant Handling COP 2007 guidelines. For a system to be considered to be fully recovered the refrigeration system standing pressure must be less than minus ten kilopascals (-10kPa - as per AS 4211.3) for most refrigeration and air conditioning systems. For chiller sets, due to their larger internal volume, this pressure is much less depending on whether the system and refrigerant is classed as a positive pressure system (e.g. R22), or a low pressure system (e.g. R11, R123). The actual values are listed in Refrigerant Handling COP (14.1.16). To speed up the recovery process you should ensure condenser and evaporator fans are operating and ensure any water pumps are running. Recovery / reclaim systems have varied from the ―wine cask‖ poly (plastic) bag type (now illegal) to the basic compressor and frame type through to a full recovery / reclaim / recycle system that can be dedicated to either a single refrigerant or various refrigerants. Recovery systems can be either of the vapour recovery type or the liquid recovery type or an integrated system combining both.

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Vapour recovery systems Vapour recovery systems consist of a small condensing unit with oil recovery and separation facilities and non-condensable separation features. To ensure a reasonable service life from the system, regular maintenance and oil changes should occur. It should be noted that these types of systems are only designed to pump vapour and therefore should be connected to the vapour side of the refrigeration system only as shown below.

Vapour recovery connections (www.wigwam.com) a) By flexible hoses equipped by a ball valve, connect the refrigerant circuit to the recovery unit as shown by the picture. b) Connect the T2 flexible hose valve (delivery) to the reclaim cylinder. c) Open the manifold valve (manifold is not supplied with the unit) d) Open the reclaim-cylinder‘s valve. e) Open the T1 and T2 flexible hoses valves (flexible hoses not supplied with the unit) g) Switch the recovery unit on.

Liquid recovery systems Dedicated liquid recovery systems consist of a liquid transfer pump, either gear or diaphragm type with a filter system. These types of pumps are only designed to pump liquid and therefore should only be connected to that side of the refrigeration system where liquid is present. They are commonly used on fully flooded systems (where the majority of the refrigerant charge is in a liquid state), such as chillers. These systems can also be used for transferring liquid refrigerant from a large cylinder to a service cylinder. The push-pull method, the recovery unit allows the rapid transfer of the liquid refrigerant from the refrigerant system to an external cylinder.

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Liquid Recovery – push-pull method (www.wigwam.com) a) Operate on the refrigerant‘s system in order that the most part of the refrigerant will be pumped in the liquid receiver b) By flexible hoses with ball valve, connect the manifold to the connection of the cooling system liquid receiver of and to the reclaim-cylinder liquid valve (with tube) (see the above figure) c) By a flexible hose (T1) with ball valve, connect the recovery unit filter drier (IN) to the reclaim cylinder vapour valve (valve without tube) d) By a flexible hose (T2) connect the exit connection (OUT) of the recovery unit to the vapour connection of the A/C system e) Open the LOW and HIGH valves of the recovery unit f) Open the V1 and V2 valves of the flexible hoses T1 and T2 of the recovery unit g) Open the connections flexible hoses ball valves h) Open the manifold valves i) Open the reclaim-cylinder valves Before use, make sure that all the flexible hoses, the filter drier, the reclaim cylinder and the recovery unit have been evacuated in advance, or that they contain the same refrigerant as the one to be transferred. Make the refrigerant‘s transfer with the refrigerant‘s system turned off. The reclaim cylinder must have a capacity equal to the quantity of refrigerant that has to be removed and must be not charged further than 80% of its maximum capacity. It is recommended the use of an electronic scale in order to check the refilling of the reclaim-cylinder Extreme caution should be exercised in relation to the safe filling capacity of the cylinder into which the refrigerant is being transferred.

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Recovery cylinders Recovery (reclaim) or pump down?

Reclaim Cylinders – also known as recovery cylinders are generally colour coded orange. These cylinders are to store reclaimed and unwanted refrigerant that is to be returned to Refrigerant Reclaim Australia (RRA) for processing and credit to your account.

Reclaim cylinder - http://www.gregsalerts.com/?city=hartford&catAbb=tls&format=hideimages&start=1400 Note! Reclaim cylinders are not to be used as Pump down cylinders.

Pump Down Cylinders – These cylinders are designed to allow contractors to recover refrigerant from a system into a cylinder known to be clean, make any repairs that are needed, and then recharge the same refrigerant back into the same system. Features • Easy to identify • Internally cleaned & valves sealed • Dual inlet & outlet valves suitable for push/pull recovery • Suitable for all common refrigerants including R410A Note! Pump down cylinders are not to be used as reclaim cylinders.

Disposing of recovered refrigerants Unwanted refrigerant that has been reclaimed can be returned to the suppliers of the reclaim cylinder. The cylinders are then transferred to RRA for disposal. Through this national collection service, recovered refrigerants are transported to a secure bank in Melbourne where they are processed, decanted to bulk storage, and then destroyed using the Australian developed plasma-arc process. This process transforms fluorocarbons into harmless salty water. Note! *RRA recovers only non-flammable, non-toxic refrigerants. Returning other material involves serious safety issues and could lead to severe injury or death for contractors or wholesalers.

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Safety and general issues when recovering refrigerant There are a few general safety precautions to observe when recovering refrigerant. 1. 2.

When recovering refrigerant from water-cooled condensers and or water / beverage chillers, the circulation pumps must be kept running throughout the recovery process. Reclaimed refrigerant can be re-used if it‘s not contaminated with non-condensable or other foreign materials. Non–condensable gases can easily be detected if the cylinder is chilled to a known temperature; say –20°C, then fit a compound gauge to the cylinder. The cylinder pressure should match the refrigerant‘s pressure / temperature relationship. Non-condensables can be removed by first chilling the cylinder to a very low temperature egg -30°C, equivalent to zero kilopascals for the refrigerant contained in the cylinder, then you can either do a minimal purge or recovery of the vapour from the top of the cylinder. Contaminated refrigerant should be returned to the supplier in the appropriately marked cylinder (see the Code of Good Practice) for disposal. This is a legal requirement as specified in the Ozone Protection Regulations.

3.

Reclaim Cylinders should be dedicated to the refrigerant being reclaimed (see the Code of Good Practice). The cylinder may contain oil that has been transferred from the system. This oil will reduce the quantity of the refrigerant that the cylinder can safely contain. The cylinder must have at least a 20% ullage (unfilled) space when full, meaning that it shall not be filled above 80% of the safe filling capacity (this will be covered in more detail later). Additionally, if the cylinder has been used as a recovery cylinder then the following should also apply:  Always check recovery cylinders regularly for internal corrosion caused by acids and moisture that could be contained in the recovered refrigerants. Best practice is to recover through an acid removal drier core, of the replaceable type.  Always check the standing pressures of recovery cylinders before using the contents for charging a job. This check allows you to see if some form of vapour contamination is present though it may not always be reliable.

4.

Chilling the cylinder during the recovery process can decrease recovery time and protects the recovery unit and cylinders from high pressures. This can be achieved by placing the cylinder in a bucket of cold water or water and crushed ice.

5.

Gauge hoses must be as short as practical and should have valves fitted to their ends to minimise losses. They should be inspected regularly for signs of leakage and deterioration.

6.

Recovery units need regular oil and drier changes to ensure optimum performance and long life of components such as the compressor and pumps. These changes should occur at regular intervals, of:  not more than 30 days usage or  not more than 200kg of refrigerant recovery or  after any use on a badly contaminated system.

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Section 7 - Pressure Testing Introduction - T7 This section is the introduction pressure testing, and includes the following topics:    

Define Pressure testing procedures and test pressures per Standards, Codes, Regulations and manufacturers requirements Safety and general issues when pressure testing refrigeration systems

Definition What is pressure testing - The pressure that is applied to test a system or any part of it for pressure tightness. (AS/NZS 1677.2:1998). As required by the Refrigerant Handling COP 2007, clause 5.31 ‗The system must be pressurised to a safe test pressure, having ensured there are no gross leaks as per 5.1.29 and 5.1.30. Before systems are put into service they shall be subject to a pressure test for system leakage. This test shall be carried out at a pressure of up to one times the maximum operating pressure. If the test is carried out pneumatically a suitable inert gas shall be used. Oxygen, any combustible gas or any combustible mixture of gases shall not be used as a test medium. Carbon dioxide or any halocarbon refrigerant shall not be used as a test medium in ammonia systems. Ammonia shall not be used as a test medium in halocarbon systems. Mixtures of HCFCs or HFCs with air shall not be used. Precautions shall be taken to prevent danger to people and to minimize the risk to property during testing.

Pressure testing Pressure testing of refrigeration systems should always be undertaken after a repair or replacement of a component in a system and is a mandatory procedure if a system has lost any of its refrigerant charge. There is a minimum test pressure that is to be achieved with each type of system whilst pressure testing. This pressure is related to the maximum operating pressure and the minimum design temperature of the system. These values are related to the summer critical process dry bulb (DB) temperature for the installation region and the refrigerant type being used (AS/NZ 1677.2). Low side: High side:

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Saturated pressure for the refrigerant type for the application is based on the summer critical process dry bulb temperature for the installation region. Saturated pressure for the refrigerant type, for the application, is based on the following criteria: (a) If a water cooled or evaporative condenser is fitted, the saturated pressure (using a pressure / temperature chart) must be equivalent to a temperature of:  16.7°C higher than the critical process DB temperature or

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UEENEEJ108A Recover, pressure test, evacuate, charge and leak test refrigerants  8.3°C higher than the highest design leaving condensing water temperature or  40°C (whichever is the greatest). (b) If an air cooled condenser if fitted, the saturated pressure (using a pressure / temperature chart) must be equivalent to a temperature of 16.7°C higher than the critical process DB temperature or not less than 50°C. Where these critical values are unknown or the unit is mobile then use the following criteria: Low side: Saturated pressure for the refrigerant type for the application based on 30°C for air-conditioned spaces or 43°C for all other locations. High side: Saturated pressure for the refrigerant type, for the application, is based on the following criteria: (a) If a water cooled or evaporative condenser is fitted, the saturated pressure (using a pressure / temperature chart) must be equivalent to a temperature of 45°C for air conditioned spaces or 46°C for all other locations. (b) If an air cooled condenser is used, the saturated pressure (using a pressure / temperature chart) must be equivalent to a temperature of 50°C for air conditioned spaces or 59°C for all other locations. Generally the following pressures apply in the field, as a rule of thumb:  Domestic systems 1,000 kPa - 1,200 kPa, to a maximum of 1400 kPa  Commercial systems 2,000 kPa - 2,500 kPa  Low Pressure Systems 100 kPa – Check manufacturers recommendations

Caution should be exercised when testing domestic systems as pressures above 1400 kPa could lead to damage to the aluminium evaporator plates that are common to this type of system. Always follow good OH&S practices at all times. High pressure regulators must always be used on nitrogen cylinders as dangerously high pressures exist in the cylinders. Standing pressure of full nitrogen / CO2 cylinders exceeds the burst pressure of flexible lines. Check hoses, hose seal rubbers and fitting regularly for wear, replace if required.

Pressure testing procedures The pressure in a system should be gradually raised with dry nitrogen or carbon dioxide. The purity of gases used for pressure testing must be 99.9% in dryness or better. DO NOT use food grade gases – they contain too much moisture and are considered to be WET.

Danger  

Never use oxygen as the pressure testing gas as most oils become explosive when placed under pressure with oxygen. Always isolate the nitrogen cylinder from the gauge manifold and disconnect the interconnecting gauge line once the test pressure is reached. This will stop pressure creep.

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2. 3.

First raise the system to the standing pressure of the system when it is at about 25°C for the designed refrigerant type - check for any obvious leaks; checking flares, fittings, solder joints etc. Raise the pressure to 1000 kPa and recheck the system for leaks. Raise the pressure to 1400 kPa maximum for domestic refrigerators or 1500 kPa for commercial systems and recheck the system for leaks. Stop here if installation is a domestic refrigerator. 1400 kPa is the maximum pressure for domestic refrigerator pressure testing.

4. 5.

For commercial systems raise the pressure to 2000 kPa and check the system for leaks. Raise pressure to between 2500 and 3000 kPa - depending on system application, refrigerant type and compressor style. Caution: R410A systems require much higher testing pressures and special gauges and lines. Standard gauges, manifolds and lines have too low a pressure rating. 

This procedure does not apply to low pressure refrigerants such as R11, R123, R113, R114 etc. due to the low normal operating pressure of the system. Maximum test pressures could be as low as 100kPa.



Check for pressure relief devices such as relief valves, rupture disks, etc. These need to be bagged (on all systems) or sealed and pressure balanced (if on low pressure refrigerant systems). Checked for leakage and during evacuation.



Maximum test pressure is related to the worst case scenario condensing pressure. Raise the pressure slowly as you could seal a leak or rupture a faulty joint. Compound gauges are NOT meant for pressure testing beyond the first initial stages up to 800 kPa, within their normal range of scale. Range is – 100 to 800 normal scale, 800 to 1700 logarithmic scale, or retarded scale. Damage will result if pressures are raised above 800 kPa.





Be aware of pressure drop due to temperature variations and allow approximately 3 kPa per 1 Kelvin (1K) change in temperature. (A Kelvin is the difference in temperature between two temperatures, i.e. between 20°C and 25°C there is 5 K difference.)

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Section 8 - Leak Detection Introduction - T8 This section is the introduction to leak detection, and includes the following topics:     

Leak detector types and applications (electronic, halide, bubble, ultra violet, Sulphur stick, litmus paper etc.) Hazards and related safe working practices (working around rotating machinery, open flame, ultra violet light etc.) Care and maintenance (delicate electronic equipment, changing sensor tip filters, changing gas cartridges etc.) Calibration (auto calibrating, send to a specialist etc.) Leak testing methods

Leak Detector Types Successful leak detection of refrigeration and air conditioning systems is an essential function of the refrigeration and air conditioning technician.

The Australian and New Zealand refrigerant handling code of practice 2007 defines acceptable leak testing methods as follows:

3.2.1 Except where used as a trace gas (see 3.2.2), fluorocarbon refrigerant must not be put into a system for the purposes of leak testing. Acceptable leak test methods include (but are not limited to): (a) liquid submersion testing (b) foam enhancer leak detection (c) positive pressure holding test / pressure drop off test (gross leaks only) (d) vacuum degradation test (gross leaks only) (e) fluorescent leak detection (f) electronic leak testing (g) mass spectrometer

Type of leak detector 1. Halide Lamp 2. Electronic Detector

Application All systems that have CFC or HCFC as the refrigerant. 

All systems that have CFC or HCFC as the refrigerant.



Some HFC systems if detector has been re-calibrated.

  3. Soapy Water 4. Fluorescent Dyes 5. Litmus paper UEE11 V1.0

An ultra-sonic leak detector is now available. Combustible gases electronic detector can be used with ammonia systems. All systems containing any positive pressure refrigerant. All systems with the exclusion of Ammonia systems. Note: Check for oil compatibility. Ammonia systems only (Changes blue litmus red). UEENEEJ108B V 0.2 Student Workbook

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Ammonia systems only (Turns solution pink). Ammonia systems only (beware of fumes).

Mass Spectrometer Test with chemical reactions and dye penetration Occasionally leaks can also be located or detected by means of chemical reactions which result in a discoloration or by penetration of a dye solution into fine openings. The discoloration of a flame due to halogen gas escaping through leaks was used earlier to locate leaks in solder joints for refrigeration units. A less frequently employed example of a chemical effect would be that of escaping ammonia when it makes contact with ozalid paper (blueprint paper) or with other materials suitably prepared and wrapped around the outside of the specimen. Leaks are then detected based on the discoloration of the paper. An example of a dye penetration test is the inspection of the tightness of rubber plugs or plungers in glass tubes, used for example in testing materials suitability for disposable syringes or pharmaceutical packages. When evaluating tiny leaks for liquids it will be necessary to consider the wettability of the surface of the solid and the capillary action; see also Table 5.1. Some widely used leak detection methods are shown – together with the test gas, application range and their particular features – in Table 5.4.

Mass Spectrometer Leak detectors and how they work Most leak testing today is carried out using special leak detection devices. These can detect far smaller leak rates than techniques which do not use special equipment. These methods are all based on using specific gases for testing purposes. The differences in the physical properties of these test gases and the gases used in real-life applications or those surrounding the test configuration will be measured by the leak detectors. This could, for example, be the differing thermal conductivity of the test gas and surrounding air. The most widely used method today, however, is the detection of helium used as the test gas. The function of most leak detectors is based on the fact that testing is conducted with a special test gas, i.e. with a medium other than the one used in normal operation. The leak test may, for example, be carried out using helium, which is detected using a mass spectrometer, even though the component being tested might, for example, be a cardiac pacemaker whose interior components are to be protected against the ingress of bodily fluids during normal operation. This example alone makes it clear that the varying flow properties of the test and the working media need to be taken into consideration.

Leak detectors with mass spectrometers (MSLD) The detection of a test gas using mass spectrometers is far and away the most sensitive leak detection method and the one most widely used in industry. Of all the available options, the use of helium as a tracer gas has proved to be especially practical. The detection of helium using the mass spectrometer is absolutely (!) unequivocal. Helium is chemically inert, non-explosive, non-toxic, is present in normal air in a concentration of only 5 ppm and is quite economical.

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Hazards and related safe working practices     

With all leak detecting methods, except for the fluorescent dyes, a positive pressures must be obtained in the system prior to leak detection. The ultra-sonic detector ―hears‖ the leak and can be used to detect vacuum leaks as well. When using soapy water be careful not to allow any solution to enter the system, this will allow moisture to enter the system causing damage. Fluorescent dyes utilise the oil as a transport agent and requires the system to be operational. Do not pressurise ammonia systems with CO2 or air, only use nitrogen as ammonia reacts violently with these two gases.

Danger



Never ever use oxygen to pressure test, as it will may cause an explosion.

Always isolate the nitrogen cylinder from the gauge manifold and disconnect the interconnecting gauge line once the test pressure is reached. This will stop pressure creep.

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Section 9 - Evacuation, Dehydration Introduction - T9 This section is the introduction to evacuation and dehydration, and includes the following topics:  Evacuation and dehydration  Deep vacuum methods  Triple evacuation  Vacuum Measurement  Instruments  Drop test  Vacuum Pumps  Types, size and applications  Use and connections  Care and maintenance  Safety and general issues when evacuating refrigeration systems

Evacuation and Dehydration Evacuation is important to ensure optimum performance of the refrigeration system. It enables air, moisture, and non-condensables to be removed from the system. The major problem of any system is contamination by moisture. By following effective evacuation procedures to dehydrate the system, this problem can be eliminated. Simple evacuation removes the air and other non-condensables such as nitrogen, oxygen, trace gases and refrigerant vapours from a system, but not water vapour. Simple evacuation is sufficient for ammonia systems where air and not moisture is the major problem. Dehydration removes water (moisture) in its vapour form. Correct dehydration techniques are necessary to keep moisture from being absorbed into the oil. 

With mineral oils (MO) and Alkyl Benzene (AB) oils, moisture is held in a physical bond. Warming these oils and evacuating to dehydration levels is sufficient for the moisture to broken from this bond and so dehydration of the system occurs.  Polyol Ester and Poly Alkylene Glycol oils hold the moisture in a chemical bond so that when they are contaminated with moisture they must be replaced. These oils must be protected from moisture at all times. There are two common methods of evacuation and dehydration; they are the Deep Vacuum and the Triple Evacuation Methods. Deep vacuum method Pull a deep vacuum to a pressure of less than 65 Pa absolute (500 microns of mercury). After isolating the vacuum pump, allow the system to stand for 60 minutes to ensure the vacuum is maintained at or below 78 Pa absolute (600 microns of mercury). Triple vacuum method Use a vacuum pump to pull a vacuum to a pressure of at least 65 Pa absolute (500 microns of mercury). Break the vacuum with dry nitrogen and allow the system to stand. Reevacuate the system and repeat the procedure twice more, breaking the vacuum each time with dry nitrogen. The nitrogen is used as a drying agent to assist the dehydration of the system.

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Vacuum measurement A deep vacuum cannot be measured accurately with the compound gauge on your manifold set as they can only measure a partial vacuum. To measure a deep vacuum a vacustat must be used. Vacustats are available in a variety of styles: 1. Electronic manometer, either analogue, digital or bar graph outputs.

2. Mercury Macleod manometer, usually laboratory grade instruments used to check other instrumentation. Vacuum Equivalents 760mm Hg = 760 000 micron = 101.325 kPa.abs = 10.33m H2O 0.1mm Hg = 1000 microns = 0.13 kPa.abs = 133Pa.abs (130kPa.abs)

Vacuum Pumps (ARAC Volume 1, Chapter 9 and Volume 2, Chapter 21) A vacuum pump is a specialised tool that is capable of pulling vacuums on a refrigeration or air conditioning system to the levels stated in Refrigerant Handling COP. They are available in two styles:  Single stage vacuum pump  Two stage vacuum pump The single stage pump is fitted with a single rotary impeller. The two stage pump is fitted with two impellers connected in series so that one pumps into the other (called 'compounding') (see ARAC Volume 2, Chapter 21). Two stage vacuum pumps will achieve deeper vacuums than the single stage version. Maintenance Vacuum pumps need regular oil changes to ensure optimum performance and long life. The period between changes will vary depending on the condition of the refrigeration and air conditioning systems that the vacuum pump is fitted to. The dirtier / wetter the system, the quicker the vacuum pump will require its oil changed. Constant monitoring of the condition and level of the oil in the pump is required. Note that the vacuum pump oil can be kept 'drier' through correct use of the ballast valve during operation and proper sealing of ports while stored.

Safety and general issues when evacuating refrigeration systems 1. 2. 3.

4. 5.

Care should be taken when evacuating excessively moist systems with large vacuum pumps (see ARAC Volume 2, Chapter 19 for further details). The larger the line diameter that connects the vacuum pump to the system the quicker the vacuum pulled (see ARAC Volume 2, Chapter 21 for further details). A ballast is fitted to most two stage vacuum pumps to avoid moisture condensing in the pump oil and reducing its efficiency (see ARAC Volume 2, Chapter 21 for further details). Care needs to be taken when introducing and releasing nitrogen from the system because of its high pressures. Never run a refrigeration or air conditioning system when it is under vacuum as the vacuum could allow electrical shorts to occur within a compressor motor.

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Refrigerant charging methods (ARAC Volume 2, Chapter 21) Basically two methods exist, liquid charging (known as bomb charging) and vapour charging. Recovered refrigerants of any type should be charged as a liquid through a burn out drier to ensure it is clean and dry and that it is free of non–condensable gases. Blended refrigerants must always be charged as a liquid. This is due to the possibility of a variation in the composition of blended refrigerants occurring during the charging procedure. This variation can also occur during system leakages.

1.

System connections and equipment for evacuation of a commercial system.

2.

System connections and equipment for evacuation of a domestic system.

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Section 10 – Refrigerant and oil charging Introduction - T10 This section is the introduction to refrigerant and oil charging, and includes the following topics:      

Refrigerant cylinders, storage and safe handling Refrigerant charging methods Vapour Liquid Safety and general issues when charging refrigeration systems including personal protection equipment Refrigerant oil removal and addition tools, procedures and safety

System refrigerant identification Trying to identify what refrigerant that is in a refrigeration system can be a challenge. Prior to the Montreal Protocol agreement, for the phase out of ozone depleting substances, there were limited numbers of refrigerants available on the market that covered a range of temperature applications, for example:  R22 for high temperature applications, such as air conditioning  R12 for medium temperature applications, such as cool rooms and domestic appliances  R502 for low temperature applications, such as deep freezers. Other refrigerants were available for different applications but will not be discussed in this student guide. Even if there was no identification provided on the system, i.e. a rating plate on the side of the unit or if the metering device were not labelled, you could do a pressure / temperature (P/T) comparison to identify the refrigerant. This was a comparison of the standing pressure (the system being equalised) against the ambient at the location of the condenser. (To equalise the system, only the fans would be left running and the refrigeration equipment turned off.) The pressure and temperature was then compared on a pressure temperature chart and the refrigerant identified. Due to the proliferation of refrigerants since the Montreal Protocol agreement, it has become more difficult to identify the refrigerant within a system (or a bottle). Again the rating plate on the side of the system or the metering device label should be checked first. It is mandatory for identification plates / stickers to be fitted to a system whenever the system is opened and / or changes made or retrofitted (to be discussed later in this Manual). A pressure / temperature comparison can still be done but there are many manufacturers‘ P/T charts that contain large numbers of refrigerants on each. Even if you do feel you‘ve identified the refrigerant using the pressure / temperature comparison, there is no guarantee that it is not a refrigerant with similar pressure / temperature characteristics. This problem is gradually being eliminated as manufacturers and the industry agrees to limited number of available refrigerants.

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Applications The following tables give you an indication of the common refrigerant‘s applications based on operating pressures and temperatures. The lists are not exhaustive as changes in refrigerant technology are occurring almost daily. APPLICATIONS AND THEIR REFRIGERANT TYPES Application R123 R404 R134 R507 R407 R22 R407 R406 A a B C A Domestic Refrigeration

X

Commercial Refrigeration Industrial Refrigeration

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

Domestic A/C

X

X

Commercial A/C Industrial A/C

X

Mobile A/C

X

Cold Storage

X

Food Processing

X

X X

X

X

X

X

X

X

X

Information provided courtesy of Kirby Refrigeration

Compressor Types Centrifugal Reciprocatin g Rotary

Screw

Scroll

Refrigerant (R11, R113, R114)

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Compressors types and their Applications Application Information Large capacity industrial air conditioning (A/C) and process chilled water applications up to 6000 kW. Wide range across all applications from domestic to industrial from smallest to largest systems available. Wide range across all applications from domestic to industrial from smallest to largest systems available. Also used as booster compressor on industrial systems Large capacity industrial A/C and process chilled water applications up to 6000 kW. Replacing centrifugal compressors. Wide range of capacities now available, with compressor motor speed control systems. Replacing rotary and reciprocating compressors.

Refrigerants (R11, R113, R114) R123, R134a, R22 All refrigerants (except R123, R11, R113, R114) All refrigerants (except R123, R11, R113, R114) All refrigerants

All non–corrosive refrigerants

Refrigerant types and their applications Compressor Application Type Centrifugal Primarily in large air conditioning systems ranging from 600 to 6 000 kilowatt (kW) in capacity and in cooling industrial process water and brine. UEENEEJ108B V 0.2 Student Workbook

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UEENEEJ108A Recover, pressure test, evacuate, charge and leak test refrigerants Refrigerant R123, R134a, R22 (R12) R134a

Compressor Type

Centrifugal Rotary

R22

Reciprocating Screw

R22

Scroll

R-13B1

Reciprocating

R-13

Reciprocating

R-14

Reciprocating

R-500

Reciprocating

R-503

Reciprocating

R-C318

Reciprocating

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Application

Wide range of applications from the large air conditioning and refrigeration systems to small household refrigerators including frozen food and ice cream cabinets, water coolers, room and window air conditioners and others. R12 was the principal refrigerant in the majority of areas. Greatest use is in residential and commercial air conditioning, and heat pumps, but was also widely used in food freezing plants, frozen food storage and cases, and in many other medium and low temperature applications. Frozen foods and ice cream display cases and warehouses, food freezing plants and as an excellent general low temperature refrigerant. Wide range of applications in both air conditioning systems and industrial cooling due to compressor responding readily to speed control. Medium low temperatures ranging down to -55°C or lower with one or two stages of compression. Low temperatures down to about -90°C in cascade systems. Very low temperatures down to about -130°C in triple cascade systems. Use to commercial air conditioning equipment to increase capacity range. Originally used to compensate for change from US to Australian frequency of supply problems (60 to 50Hz). Low temperatures down to about -90°C. With a lower boiling point and higher capacity than R-13, it is competitive with ethylene and ethane with the advantage of being nonflammable. Air conditioning in high ambient temperatures such as overhead crane cabs in steel mills and Is one of the most thermally stable of the fluorocarbon refrigerants.

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Safety classification groups (ARAC Volume 1, Chapter 1) The current refrigerant safety classification system, referred to in AS/NZS1677.1 Section 3, utilises an alpha–numeric matrix. This matrix is supported internationally in The American Society of Heating Refrigerating and Air-conditioning Engineers (ASHRAE) Standards 15 and 34.

Higher Flammability (3) Lower Flammability (2) No Flame Propagation (1)

Lower Toxicity (A) A3 egg. R600a A2 egg. R143a A1 egg. R134a

Higher Toxicity (B) B3 (no refrigerants in use today) B2 eg.R717 B1

See Section 2 of AS/NZS 1677:1998 classification system refers to the refrigerant groups listed above, for further details.

Safety precautions with new generation Ozone friendly refrigerants – High capacity, high pressure refrigerants Retrofitting of systems to high capacity, high pressure refrigerants Mandatory changes to the system when retrofitting to high capacity, high pressure refrigerants such as R410a would include compressors, thermostatic expansion valves, sight glasses and a compatible liquid line filter drier. Polyolester (POE) lubricants are recommended. Other high pressure side components, including condensers and compressors would also require replacing. Even low pressure side components may require changing depending upon local building codes permit and equipment manufacturers approve. Additional high capacity, high pressure refrigerant safety precautions  

High pressure gauges on manifolds must have a high pressure working limit exceeding 5500kPa. Low pressure compound gauges must be scaled / calibrated to read accurately, –100 0 - 1700kPa, and then logarithmic/retarded to 3400kPa.



Gauge lines must have operating/safe working pressures exceeding 5500kPa, with burst pressures exceeding 21Mpa.



Cylinders must have a working pressure rating above 4.8Mpa and be kept out of direct sunlight, especially in warm weather. The cylinder must never be allowed to get warmer than 52°C.

Cylinders There are two types of cylinders in common use by companies: 1. Refillable pressure vessel type cylinders. These are fitted with pressure relief devices such as relief valves or fusible plugs and they come in various sizes designated by code letters. They must be inspected regularly. General rules for handling refrigerants and cylinders Safety should always be a major consideration as cylinders are transported regularly in the back of service trucks in summer so keep cylinder safety in mind. Do not overfill them as over–pressurisation can occur and liquid filled cylinders will hydraulic lock and burst. Cylinders should be filled to 80% of their maximum possible contents / volume as recommended in Australian Standards. The following are some basic general rules that apply to the handling of all cylinders: UEE11 V1.0

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















 

 

Safety Equipment: Goggles or face shields, gloves and safety footwear must be worn when filling cylinders, coupling up storage vessels and / or handling bulk fills. This is done to prevent eye damage or burns should a coupling give way or a line burst. Store Cylinders Upright: Store cylinders in a cool, dry place, away from direct sources of heat. A well ventilated area will ensure that no build up of gas can occur should a cylinder leak or relief valve operate (unseat). Do not force connections: Cylinder connections should fit easily and snugly. You should never force connections. Always use correct tools when tightening or loosening fittings. The use of incorrect tools can cause stripped threads or damaged fittings, which can cause leaks and possible loss of refrigerant to the atmosphere. Handle Cylinders Carefully: Cylinders should not be used for ‗rollers‘ or supports as cuts and abrasions on the cylinder body or yourself may result. Care in handling cylinders will prolong their life. Read Labels: As mentioned, because colour of cylinders cannot be relied upon for positive identification, labels should always be read carefully. Colour blindness might interfere with proper identification. If still in doubt, other methods of identification are available such as pressure / temperature relationships or other methods available from the manufacturer / supplier. Visual Examination: Each time a cylinder is returned for re-charging, it should be carefully examined for evidence of corrosion, cuts, dents, bulges, condition of threads, valves etc. to ensure suitability for further service. State Codes also provide for examination and testing of cylinders to ensure their continued use. Never transfer between unmarked cylinders: Refrigerant cylinders are labelled and identified for a particular refrigerant. Never put a different refrigerant into a cylinder labelled for a particular refrigerant. Keep refrigerant and cylinders away from fire: No part of any cylinder should ever be subjected to direct flame, steam or temperatures exceeding 50ºC. If it is necessary to warm cylinder to promote more rapid discharge, extreme caution should be taken. An easy and safe way is to place the bottom part of a cylinder in a container of lukewarm or hot water not over 45ºC. (See Refrigerant Handling code of practice 2007) Check Pressure: The pressure within the cylinder must be greater than in the system to cause the refrigerant to flow into the system. The pressure should be checked before charging. Disposable cylinders: Never refill disposable cylinders. Most have safety devices to prevent this occurring such as a one way value. Cylinder Inspections: Ensure normal cylinders are inspected at 10 year intervals, as prescribed by the relevant State / Territory / Federal code, as they are classified as a pressure vessel. Safety devices: Do not defeat / block the safety valve in the stem as this could lead to the cylinder rupturing. Ullage space: Cylinders must have a 3% ullage space (vapour space) at 57°C as specified in AS2030. Ullage space is the space provided for vapour volume in a cylinder during the worst summer condition.

Safe filling of cylinders Cylinders should never be liquid filled or filled above the safety limit as any change in temperature can cause severe changes in pressure to occur and this could destroy the cylinder.

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Cylinder Terminology WC = Water Capacity, internal volume of cylinder at 100% full FR = Fill Ratio, factor for filling cylinders safely, listed in AS2030 SFC = Safe Filling Capacity of a cylinder. Calculating the Safe Filling Capacity (SFC) of a cylinder Two methods of calculating the safe filling capacity of a cylinder are used: 1. Density method 2. Water Capacity method Density Method This method is based on the calculated internal volume of the vessel, the density of the refrigerant at 25°C and a safety factor of 80%. This value is used to calculate the quantity of refrigerant that can safely be decanted into a vessel of unknown water capacity. SFC = Vint x  x 80% Where:  SFC = Safe Fill Capacity, in kilograms (kg) 

 = Density of refrigerant, in kilograms per litre (kg/L) or kilograms per metre cubed (kg/m3)



v = Volume, internal volume of cylinder in cubic metres (m3).

The internal volume is calculated using Vint 

d 2 h 4

Where:  Vint = Volume in cubic metres  

d = Internal diameter of the cylinder in metres

h = Length of the cylinder in metres

 Refrigerant R22 R123 R134a R717 R404A

Density 1174 kg/m3 1426 kg/m3 1202 kg/m3 595 kg/m3 1040 kg/m3

Examples A receiver is 1200 mm long and is 900 mm round. What mass of R22 can safely be filled into this container, assuming the cylinder has flat ends?

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Solution SFC = Vint x  x 80% SFC = x 0.9m2 x 1.2m x 1174 kg/m3 x 80%

4 SFC = 717 kg

Water capacity method Used where the cylinder is a manufacturers‘ known type and the following formulae applies: SFC = WC x FR Where:  SFC = Safe Fill Capacity, in kg  WC = Water Capacity, in kg  FR = Fill Ratio Filling ratio for all common refrigerants and substances are available in Australian Standards. Refrigerant R22 R134a R404A R407C R410A R507

Fill Ratio 1.03 1.05 0.9 0.95 0.8 0.9

Example A cylinder has a WC of 22 kg and is to be filled with R404A. The cylinder has a tare mass of 9.5 kg. What mass of R404A can safely filled into this cylinder and what will the cylinders gross mass be when filled? Solution  SFC = WC x FR SFC = 22 kg x 0.9 SFC = 19.8 kg  Cylinders gross mass when filled = SFC + Cylinders tare mass

Gross Mass = 19.8 kg + 9.5 kg Gross Mass = 29.3 kg

Refrigerant decanting methods Refrigerant can be decanted into cylinders / receivers by using: 1. Pressure and temperature differentials. 2. Gravity but needs a temperature difference allow decanting to occur faster. Method 1 and 2: Chill cylinder to be filled (evacuate if possible – evacuation will be discussed latter in this module) and warm cylinder to be decanted from by using a controlled heat source (as recommended by the Codes of Practice). Such a heat source may be a fan heater, heat lamp, or heat blanket but in doing so you must not raise cylinder temperature to over 45°C. 3. Vapour compression transfer system. You can utilise a standard recovery unit to do this job. 4. Liquid transfer pump system. You can utilise a liquid recovery unit to do this job. UEE11 V1.0

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Decanting procedures The following procedures assume a specific type of system is available to use, one fitted with Hansen couplings and adaptors. Using a vapour transfer system 1. Attach a cylinder adaptor and short gauge line to the bulk storage cylinder. Fit a Hansen coupling to the end of the gauge line, open the bulk cylinder vapour valve and purge the line with vapour at the Hansen coupling, with minimal losses.

Warning:

Ensure the line is connected to the cylinder and the Hansen coupling before connecting the Hansen coupling to a vapour transfer system fitting. 2. 3.

4.

5. 6. 7.

8. 9.

Connect the bulk cylinder to the male inlet coupling of the vapour transfer system, using a female Hansen coupling. Turn on the scales, allow zeroing and stabilising of readings. (a) Identify the refrigerant type that the service cylinder contains. (b) Ensure that the service cylinder is not contaminated. (c) Ensure the refrigerant type in the bulk cylinder matches the service cylinder. Place the service cylinder on scales; record the mass of cylinder on an individual record audit sheet and calculate safe filling quantity that can be decanted into the cylinder. Fit a bottle adaptor to the service cylinder then connect a gauge line fitted with a small quick-connect hand valve to the adaptor. Connect the female Hansen coupling to the free end of the gauge line and purge the line at the Hansen coupling, ensuring minimal losses. Connect the Hansen coupling, from the service cylinder to the male outlet coupling of the vapour transfer system. Ensure the bulk cylinder outlet valve, service cylinder inlet valve and quick–connect valve are fully open and then turn on the vapour transfer unit. Fill the cylinder until the gross mass on the scales matches the required gross mass on the audit sheet. Turn off the vapour transfer system and then shut off the service cylinder valve and quick-connect valve. Remove the quick-connect valve from cylinder and record the mass of the cylinder on an individual record audit sheet, as required by legislation. If no further cylinders are to be filled or when finished, shut all the service valves on all cylinders. Disconnect both Hansen couplings, slowly and carefully release the refrigerant from the gauge lines by undoing them from the Hansen couplings. Use a rag to cover the ends of the hose when doing this.

Using a liquid transfer pump system 1. Attach a cylinder adaptor and short gauge line to the bulk storage cylinder. Fit a Hansen coupling to the end of the gauge line, open the bulk cylinder vapour valve and purge the line with vapour only at the Hansen coupling, with minimal losses.

Warning:

Ensure the line is connected to the cylinder and the Hansen coupling before connecting the Hansen coupling to a vapour transfer system fitting. 2.

3.

Invert the bulk cylinder to ensure there is a full head of liquid at the transfer pump. Connect the bulk cylinder to male inlet coupling of the liquid transfer system, using a female Hansen coupling. Turn on scales, allow zeroing and stabilising of readings. (a) Identify refrigerant type the service cylinder does contain. (b) Ensure that the service cylinder is not contaminated.

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UEENEEJ108A Recover, pressure test, evacuate, charge and leak test refrigerants (c) Ensure refrigerant type in bulk cylinder matches the service cylinder. Place the service cylinder on scales; record the mass of cylinder on an individual record audit sheet and calculate safe filling quantity that can be decanted into the cylinder. 4.

Fit a bottle adaptor to the service cylinder then connect a gauge line fitted with a small quick-connect hand valve to the adaptor. Connect the female Hansen coupling to the free end of the gauge line and purge the line at the Hansen coupling, ensuring minimal losses.

5.

Connect the Hansen coupling, from the service cylinder to the male outlet coupling of the liquid transfer system. Ensure the bulk cylinder outlet valve, service cylinder inlet valve and quick–connect valve are fully open and then turn on the liquid transfer unit. Fill the cylinder until the gross mass on the scales matches the required gross mass on the audit sheet. Turn off the liquid transfer system and then shut off the service cylinder valve and quick-connect valve. Remove the quick-connect valve from cylinder and record the mass of the cylinder on an individual record audit sheet, as required by legislation. If no further cylinders are to be filled or when finished, shut the bulk cylinder valve. To minimise losses to atmosphere of the refrigerant, connect a spare cylinder to the outlet valve of the liquid transfer pump as per the instruction above (in part 4). Open the service cylinder valve and quick-connect valve, and turn on the liquid transfer unit for a very short time. Turn off the liquid transfer pump and disconnect both Hansen couplings. Slowly and carefully release refrigerant from the gauge lines by undoing them from the Hansen couplings, using a rag to cover the ends of hose.

6. 7.

8. 9.

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Observational exercise – Cylinder markings Task To observe typical refrigerant cylinders and identify the various marking found.

Equipment 

Various refrigerant cylinders

Safety   

 

Observe all safety precautions as explained by your teacher. Wear safety glasses at all times in the workshop. Refrigerants must not be vented to the atmosphere as they are asphyxiants and could be ozone depleting. Liquid spillages will cause low temperature burns on unprotected skin areas. Wear hearing protection if noise levels in workshop are high or are of concern to you. Remember electricity kills. These items of equipment are electrically live and operational, on 240V.

Procedure 1. 2.

Check that the various cylinders presented to you Inspect the cylinders and locate the following markings:  WC  AS  Tare Mass  Test Date Stamp  Test Pressure  Any other relevant markings Marking

Meaning

WC AS Tare Test Date Test Pressure Other relevant information

Value, if relevant kg kg MPa



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Section 11 - System Contamination Introduction - T11 This section is the introduction to system contamination, and includes the following topics:        

Contaminants (Non-condensables, moisture, acids, carbon, copper etc.) Effects of contamination (Acid, motor burnout, oil contamination, copper plating, seizing, RMD blockage, excessive condensing temps etc.) Practices/procedures that cause contamination Methods and components use to remove contamination Filter dryers – liquid, suction, burnout Dry nitrogen Flushing agents Evacuation

Contaminants (Non-condensables, moisture, acids, carbon, copper etc.) There are many factors governing the entry of contaminants into a system. These include, but are not limited to the following: (a) Poor installation techniques  Poor work practices (b) Using contaminated products and supplies such as pipe, refrigerant and oil  Component failure being either sudden, slow, mechanically or electrically based; contamination level and clean-up procedure vary with failure style. There are many contaminants found in refrigeration systems. They include, but are not limited to the following: (a) Non-condensable vapours such as nitrogen or air (b) Foreign objects such as welding rod, bricks, debris, copper swarf, drill bits, dirt, solder residues, flux residue, etc.

(c) Moisture (d) Oil (e) Carbon scale        

Contaminants (Non-condensables, moisture, acids, carbon, copper etc.) Effects of contamination (Acid, motor burnout, oil contamination, copper plating, seizing, RMD blockage, excessive condensing temps etc.) Practices/procedures that cause contamination Methods and components use to remove contamination Filter dryers – liquid, suction, burnout Dry nitrogen Flushing agents Evacuation

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Contamination by-products Once contaminants enter a system, they cause chemical and physical changes within the system. They can also cause abrasion of bearing surfaces. Some of these by–products are:

(a) Acids (b) Sludges (by–products of electrolysis, abrasion and corrosion) (c) Copper-plating of iron based and other less noble metal components (electrolysis) egg. valve plates, bearing surfaces.

Contamination results and indicators Once a system is contaminated, an observant refrigeration mechanic will notice many operational indicators. Some of these are: (a) Restriction of strainer / drier

(b) Restriction of metering device inlet orifice (c) Seizure of compressor (d) Compressor valve failure

Clean-up procedures Filter driers (ARAC Volume 1, Chapter 6 and Volume 2, Chapter 18) Filter driers are a necessary part of any refrigeration or air conditioning system to filter contaminants like dirt, acid, sludge and varnish from the system as well remove moisture from the system. They are available in a variety of types: 

Liquid line filter driers - both single [mono] direction flow and two [bi] directional flow - available in a variety of sizes to suit domestic through to industrial applications - sealed or replaceable core  Burn out driers - suction line filter driers (installed in the suction line for system clean-up after a sealed unit motor burn out) - Sealed or replaceable core driers The filter drier core is:  made up of a blend of desiccants (moisture removing substances) that has the added ability of removing acids and the products of oil composition. Suction line filter driers have the addition of activated charcoal to further increase the acid clean up capability after a burn out.  mesh screens can be installed as well, as a safety filter to remove larger particles.  porous which gives it the ability to remove the finest of particles.

Bi directional drier Mono directional drier UEE11 V1.0

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Cut away diagrams showing drier cores Pictures provided courtesy of Sporlan Valve Company

Driers are also available as replaceable core types. As the name suggests, the core can be removed and replaced. This type of drier is used in larger systems in the liquid line but is often installed into systems that have had a burn out. As the cores become blocked (identified by a pressure drop across the drier) they are removed and replaced with new cores. Further core changes are carried out until there is no further pressure drop. This is done in combination with measuring the acid build up in the oil using oil test kits.

Domestic refrigerator driers Pictures provided courtesy of Actrol Parts

Cut away diagrams showing drier cores from a replaceable core drier Picture provided courtesy of Sporlan Valve Company Selection The selection of a filter drier will depend on:  The line size and style of connection (flare or solder) 

The water capacity of the drier (its ability to remove sufficient quantities of moisture content to a safe level.) This is a function of the surface area of the drier core.

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The flow capacity of the drier (it must be sufficient to avoid a pressure drop across the drier)

 

The type of refrigerant in the system The safe working pressure of the drier (especially important with the high pressure refrigerants like R410a).

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The type of drier core (acid removal, normal desiccant, etc)

Installation 1. The system must be pumped down and any refrigerant left must be recovered. Do not remove the sealing cap from the new drier until it is ready for installation. 2. A liquid line drier should be fitted as close as possible to the metering device inlet. Suction line driers should be fitted as close as possible to the compressor. Most driers UEE11 V1.0

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UEENEEJ108A Recover, pressure test, evacuate, charge and leak test refrigerants can be installed in any position (vertical or horizontal). If the system is fitted with a moisture liquid indicator (sight glass), make sure the drier is located upstream from the indicator. 3. The drier has an arrow showing the required direction of flow through it. It must be installed in the correct direction or the efficiency of the drier will be reduced. 4. If the drier is a solder type, wrap the body with wetted rags. When soldering aim the flame away from the body to avoid internal damage. If the drier is a flare type, use two spanners to avoid twisting of the refrigeration lines. 5. Leak test the newly installed drier for leaks.

Procedures for clean up The procedure for cleaning up contamination in a system will depend on the type and extent of the contamination. The following clean up procedures can be taken to correct the contamination faults:

Non condensables in the system The system should be recovered, evacuated and then recharged with clean refrigerant.

Foreign objects / carbon scaling If the foreign objects are small enough they will reach the drier. This will be indicated by a temperature drop (colder on the outlet than the inlet). If possible, pump down liquid line where the drier is located (a partial charge only). If this is not possible the whole charge will need to be recovered. Replace the drier, evacuate and charge as previously described in this module. If the foreign object is in a different part of the system (i.e. the metering device), the same procedure of either pumping down part of the system or a complete recovery should be done. Remove, clean or replace the component affected by the foreign object. Evacuate and charge as previously described in this module.

Moisture If the moisture contamination is not too great, you may only need to replace the liquid line drier. Either pump down the system or recover the refrigerant charge and change the drier. Evacuate and charge as required. If the moisture contamination is too great, you will need to recover the refrigerant charge, replace the drier and carry out a triple evacuation. The dryness of the nitrogen will attract the moisture in the system and assist in its removal from the system. Once the appropriate vacuum is held (identified using a vacustat), the system can then be charged as previously described in this module.

Motor burnout clean-up (Acid / Oil contamination Should the system become burnt out due to any of the contamination problems listed above or those causes shown in ARAC Volume 2, Chapter 21, the clean up procedure is much more complicated than that shown in the previous contamination clean ups listed above. The procedure to clean a system that has had a burnout is listed in ARAC, Volume 2, Chapter 21).

Safety and general issues related to contaminated systems 1. If a non-condensable is found in a system, the reason for the non condensables presence should be identified. If it is air it may be because there is a leak on the low

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2.

3. 4. 5. 6. 7.

side of the system, if it is nitrogen it is more than likely that it is in there because of bad work practices. If it is a leak, locate and repair it before evacuating and charging. If moisture is identified in the system (i.e. the site glass moisture indicator is showing wet refrigerant), the moisture should be removed to avoid any problems that it will cause (copper plating, acid build up in the oil, blockages, etc.). The procedures listed in ARAC to deal with a burnout should be followed, as the likelihood of another burn-out occurring would be high. If the refrigerant has decomposed, avoid its inhalation. Avoid contact with oil or refrigerant that has become decontaminated. Use rubber gloves when working around oils. Ensure proper ventilation.

Oil compatibility Most new compressors and condensing units are charged with Polyol Ester oils (POE) and care must be taken when changing compressors on older installations, especially if retrofitting of systems, after a major leak or service, to HFC or HFC blend refrigerants. Ester oils are better solvents than the mineral oils and will scrub a system clean so clean up type driers should be fitted with the new compressor. You need to check the operational history if the system has had a previous burn out or similar failure. If it has, then the system will need to be flushed due to the solvent nature of Ester oils. Depending on the colour of the oil, flush the sump and refill the sump with the correct quantity of Ester oil. Obtain a sample of the oil to test for contamination by mineral oils or other contaminants. It is recommended that the oil sample be between 95 to 99% pure Ester if HFC or HFC blends are used. NOTE: a. Suitable flushing systems use solvents to remove oil residue (methylated spirits for very small systems; trichloroethylene, perchlorethylene or R141b for all systems). b. Oil can be tested using either a refractometer or oil solvent test kit or laboratory testing. c. Ester oil is a very good solvent and will remove any residual particulate contaminants from the system, flushing them to the strainer / drier or sump. d. Label system as per HB40 regarding oils and servicing.

Overview of retrofitting The following information briefly outlines an acceptable retrofit procedure that could be used on systems. This will be covered in greater detail in a latter module (NR48). Procedure 1. Establish baseline data if the plant will run correctly, as this will be the information that you will be comparing to after the retrofit is complete. The following information needs to be collected:  The suction pressure (kPa)  The discharge pressure (kPa)  The current draw of the compressor (amps)  The power consumption (kilowatts)   

The condensing temperature (°C) The condensing temperature difference (TD in K) Evaporating temperature (°C)

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2. 3. 4. 5. 6. 7. 8.

9.

 Evaporator temperature difference (TD in K) Check the operational history. Has the system had a previous burn-out, if so the system will need to be flushed? Rectify any operational faults. Recovery the existing refrigerant. Drain the oil from the compressor, measure the oil quantity removed and compare it to the manufacturer‘s data sheets. Refill the sump with the recommended grade of Polyol Ester oil. Check with the manufacturer as to compatibility of the compressor, seals, etc. with Ester oils. Pressure test the system, evacuate and recharge with the original refrigerant. Run the system. Pump down the compressor, recover the residue refrigerant and drain the oil. Measure the oil quantity. Depending on colour of the oil flushed from the sump, refill sump with the correct quantity of Ester oil. Pressure test the compressor, evacuate and open the compressor to the system. Run the system. Repeat step 7. Test the oil sample removed for contamination for mineral oil or other contaminants. When oil sample is 95 to 99% pure Ester, recover complete charge, replace the drier and metering device. Pressure test the system, evacuate and then recharge with new refrigerant.

NOTE: a. This procedure can be deleted by using a suitable flushing system using solvents to remove oil residue (methylated spirits for very small systems; trichloroethylene, perchlorethylene, Netelfit 22 or R141b for all systems). b. Oil can be tested using either a refractometer or oil solvent test kit or laboratory testing. c. POE oil is a very good solvent and will remove any residual particulate contaminants from the system, flushing them to the strainer/drier or sump. 10. Collect data as per step 1, and compare the results. Reset pressure controls and any pressure sensing devices such as Evaporating Pressure Regulator (EPR) and Crankcase Pressure Regulator (CPR) valves. Optimisation of metering device settings may also be required. If capillary, modification to its length may be required 11. Label the system as per the Code of Practice.

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