Hydrological Services Pty Ltd
Model HS-40/HS40DO Advanced Bubbler System Installation and Operation Manual
HYDROLOGICAL SERVICES Pty Ltd 48-50 Scrivener Street Liverpool NSW 2170 Australia Ph. 61 2 9601 2022 Fax. 61 2 9602 6971 Internet: www.hydrologicalservices.com E-Mail:
[email protected] Gas Purge Compressor © Copyright
Air Force 100-1 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
TABLE OF CONTENTS 1.
Introduction........................................................................................ 3
2.
Product Overview .............................................................................. 4
3.
Installation .......................................................................................... 5
3.1 3.2 3.3
4 4.1 4.2 4.3 4.4 4.5
Extending the Battery Cables ............................................................................. 6 Adjusting the Bubble Rate .................................................................................. 7 WL3100 Connection ............................................................................................ 7
Operation ............................................................................................ 8 Description of Controls........................................................................................ 8 Startup Sequence ................................................................................................. 10 Tank Pressurisation ............................................................................................. 10 Battery Size ........................................................................................................... 10 Battery Indication ................................................................................................ 11
5.
Maintenance ....................................................................................... 12
6.
Fault Finding ...................................................................................... 12
7.
Specifications ...................................................................................... 14
Appendix A WL3100 Operation Manual ...................................................... 15 Appendix B Installing Polyethelene Tubing and Orifice Fittings ............... 29 Appendix C Using Pressure to Measure Water Level.................................. 31 Appendix D HS-40DO (Dual Orifice) ............................................................ 38 Features of Dual Orifice ....................................................................................................... 38
Appendix E Gas Chamber Orifice Assembly .................................................. 39 Typical installation for HS-40 & HS-40DO (Dual Orifice)............................ 41
Gas Purge Compressor © Copyright
Air Force 100-2 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
1.
Introduction
The HS-40 Gas Purge Compressor + Bubbler System has been designed to replace conventional nitrogen gas bottle supply to bubble units / gas purge systems, used for measuring water level in dams, rivers, canals and tanks with up to 30 mH2O (100 ft) head. The basic system consists of an air compressor, a 2 litre receiving tank, a twin mist separator air dryer and a bubbler system all built into a single small enclosure. The system continually monitors the tank pressure and when it falls below 400kPa (58 psi), the compressor will start and pump the tank pressure back up to 750kPa (110psi). The HS-40, with the optional inbuilt WL3100 pressure transducer, allows the measurement of water level to an accuracy of ±0.02% F.S. (The WL3100A is a more advanced model that allows the fine tuning of the “user factor” relationship between pressure and water level, and is temperature compensated from –40oC to 80oC) The inbuilt WL3100 / WL3100A have an SDI-12 interface and a 4-20mA interface that can be used at the same time to provide data to 2 separate systems if required. Advantages over other systems:
Compact single unit.
Maintenance free (no gas bottle or desiccant to be replaced) – the air dryers have an auto-drain moister trap feature that sense moisture build up and purge it to atmosphere.
Can interface to SDI-12 and 4-20mA outputs simultaneously.
Easy to install.
There are 3 separate models available: HS40
- Includes compressor + tank + air dryer + bubbler
HS40 / 3100
- Includes compressor + tank + air dryer + bubbler + inbuilt WL3100
HS40 / 3100A
- Includes compressor + tank + air dryer + bubbler + inbuilt WL3100A
Gas Purge Compressor © Copyright
Air Force 100-3 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
2.
Product Overview
The Air Force Model HS-40 is designed to replace conventional Dry Nitrogen bubbler systems. A dot point view of the product is as follows :
Maintenance free gas purge system for water level measurement. In-built Air Compressor. 2 litre Receiver Tank. Can be used with any pressure transducer. (optional built-in WL3100) Operates with up to 30m (100ft) head of water. Low power consumption. True continuous bubbler system – can be used with or without a Gas Chamber Orifice. User adjustable bubble rate.
Internal view of the Air Force Model HS-40. The built-in WL3100 Pressure Transducer fits in the top right of the cabinet.
Gas Purge Compressor © Copyright
Air Force 100-4 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
3.
Installation
The HS-40 must be mounted in a vertical position. The air dryers will not function properly if the unit is in a horizontal position.
Manual Start Dual Air Dryers
WL3100 Connections
Before connecting power to the HS-40, fit the 3/8” River Line 3/8 inch river-line as shown.
12V Battery Cable
Connect the 12V DC battery to the orange power cable shown, and add a mains or solar charger if required.
Built-in WL3100
Tank Pressure River Line Select Valve
Test Port
The status LED, at the bottom Valve allows right of the cabinet, will cycle transducer calibration to be checked through its initial sequence, and then if the tank pressure is less than 400kPa (58psi), the Status indicator compressor will start and LED pump the tank pressure up to 750kPa (110psi). This initial pump up cycle may take several minutes. 3/8”
Bubble rate adjust with lock screw
River Line WL3100 Power + SDI-12 / 4-20mA Interface
-
+
12V 38Ah Battery
Gas Purge Compressor © Copyright
Air Force 100-5 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
3.1
Extending the Battery Cables
The HS40 is supplied with a 2m power cable, with each core being 2.5mm2. If the user needs to extend this cable, extreme caution should be exercised, because whenever high currents are drawn through cables, there will be voltage drops !!! With the supplied cable (2m of 2.5mm2) there is a 0.2V drop on each conductor when the compressor draws 15A. Since there is a positive and negative wire, the voltage seen by the HS40 is 2 x 0.2V = 0.4V less than the voltage seen at the battery terminals – and at 15A the battery voltage will also droop. (This is before the cables are extended.) HS40
VHS40 = Vbatt – Vdrop1 – Vdrop2 VHS40 Extended Power Cable (Vdrop1)
Supplied Power Cable (Vdrop2)
Vbatt 12V Battery
Use the following table to get an idea of the total cable voltage drop, keeping in mind that small batteries droop more under heavy load – and the HS40 will disconnect the compressor when the voltage “it sees” drops below 10V. (This was 11V in units prior to S/N 10-142). Extended Cable Length
Cable Size (mm2 / AWG)
2m (6ft) 2.5 / 13 4m (12ft) 2.5 / 13 6m (18ft) 2.5 / 13 6m (18ft) 10 / 7 10m (30ft) 10 / 7 15m (45ft) 10 / 7 15m (45ft) 16 / 5 20m (60ft) 16 / 5 * => Not Recommended
Vdrop1 on extended cable
Vdrop2 on supplied cable
Total Vdrop
0.4V 0.8V 1.2V 0.3V 0.5V 0.8V 0.5V 0.7V
0.4V 0.4V 0.4V 0.4V 0.4V 0.4V 0.4V 0.4V
0.8V 1.2V 1.6V 0.7V 0.9V 1.2V 0.9V 1.1V
Battery Voltage Vbatt when HS40 disconnects compressor 10.8V 11.2V * 11.6V * 10.7V 10.9V 11.2V * 10.9V 11.1V
NOTE : Increasing the battery capacity (to say 38Ah or higher) also helps, because the battery voltage will droop less under heavy load. Gas Purge Compressor © Copyright
Air Force 100-6 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
3.2
Adjusting the Bubble Rate
Set the River Line control valve to the “Close” position. (Keep the Calibrate valve in the “Open” position) Attach the HS23QC (supplied as standard) to the HS40 Test Port and immerse the HS23QC in a beaker of water. Allow up to 10 minutes for the bubble rate and differential regulator to stabilize. Undo the bubble rate lock screw and adjust the bubble rate (to say 21 bubbles/min) The bubble rate at the Test Port will be the same as would be at the River Line orifice. Nip up the lock screw and test the bubble rate again – it may change slightly as the lock screw is done up. Disconnect the HS23QC from the HS40 Test Port. Rotate the River Line control valve from the “Close” position to the “Open” position to direct the bubbles from the “Test Port” back to the “River Line”.
*** Warning : Close the river line when using the test port
Test Port
HS23QC
Bubble rates will be the same. Refer to table
3.3
RiverLine
Actual Bubble Rate setting at Test Orifice or River Line (bubbles/min)
Suitability
Equivalent Site Glass Bubble Rate (bubbles/min)
10 16 21
Suitable for Slow rising streams
40 60 80
26 32 48 65
Suitable for Fast rising streams
100 120 160
Recommended setting for Gas Chamber Orifice, Model GC01P installations
200
WL3100 Connection
12 +12V DC Power The wiring connections to the WL3100 are via a plug-in Da SDI-12 Data terminal block underneath the HS40 enclosure. You must have 0V 0V DC Power +12V and 0V power for the WL3100 to operate. You may +S +ve 4-20mA Signal connect the SDI-12 and the 4-20mA interfaces at the same -S - ve 4-20mA Signal time. (These terminals are “screwless” and keep a constant tension on the wire, thus producing a more reliable connection – simply use a screwdriver to push on the orange lever to release the terminal spring tension, to insert or remove the wire.)
(Consult the WL3100 Manual in Appendix A for a detailed description of the WL3100 connection and operation.) If connecting to the 4-20mA interface, make sure that the data logger (or RTU) powers up the 4-20mA loop long enough for the WL3100 to recognize it, take a measurement and put the result back on to the 4-20mA loop. (5 secs when “Continuous Mode” is set to “YES” and 15 secs when “Continuous Mode” is set to “NO”) Gas Purge Compressor © Copyright
Air Force 100-7 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
4
Operation
4.1
Description of Controls
Manual Start button : The operator may manually “start” a tank pump up cycle by pressing the blue button “underneath” the enclosure. This button also provides a manual “stop” of a pump up cycle – and will cause the blue LED to flash slowly indicating the pump up cycle was not completed. Note : The compressor has a manufacturer’s maximum duty cycle of 10%. If the compressor is on for 1 minute, make sure it rests for 10 minutes. DO NOT purge or perform manual pump up cycles un-necessarily.
Status LED indicator : Flash => Everything is operating normally. Flash => Battery voltage is low. (If the battery voltage falls below 10V, the LED will flash red, and will only return to a green flash when the voltage rises above 12V) Slow Flash => There is a problem with the compressor / tank pressure. Possible causes are: - Max tank pressure could not be reached within 3 mins – this could be due to a leak in the tank / tubing, or the compressor has lost its capacity to pump. - Tank pressure was not increasing while the compressor was on – a possible leak in one of the joints. - Could also be due to a manual “stop” by the operator during the pump up cycle. Even when the LED is slow flashing blue, the system will attempt to pump up the tank every 12 hours. Fast Flash => The compressor on/off duty cycle of 10% has been exceeded. The system will wait for 30 mins and then automatically complete the pump up cycle.
Gas Purge Compressor © Copyright
Air Force 100-8 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
River Line Control Valve : This Control Valve has 3 positions: “Open” In the Open position, the bubbler (regulator) is open to the River Line port and the transducer. “Close” In the Close position, the bubbler (regulator) is closed to the River Line. (If there is nothing plugged into the Test Port Quick Connect, the transducer pressure will continue to increase very slowly as the regulator reacts to a closed system – DO NOT leave it in this position for extended periods as the internal pressure build up may exceed the burst pressure of the transducer element !!!!) “Purge” In the Purge position, the receiver tank is directly connected to the River Line port to allow a Purge of the River Line. After a River Line Purge is performed, rotate the control valve back to the Close position and wait until the River Line pressure drops to a normal level (say 5 secs) before rotating the control valve back to the Open position. (Otherwise the Purge pressure may be introduced to the transducer and cause damage !!!) **** IMPORTANT **** When purging, STOP when the tank pressure falls below 400kPa, otherwise the riverline pressure may fall below the water head pressure resulting in water entering the River Line !!!
Calibrate Valve : The Calibrate Valve is used to allow the “Bubble Rate Test Port” to be used to check the transducer (WL3100) calibration. The procedure is as follows:
Set the “River Line Select” valve to the Close position. Set the “Calibrate Valve” to the Calibrate position. Set the pump up calibrator to “vent” so that the existing water head pressure is vented during the next step. Connect the pump up calibrator to the Bubble Rate Test Port. The pressure from the pump up calibrator can now be applied directly to the transducer (WL3100) input. Set a required pressure (or water level) on the pump up calibrator, then read the water level from the transducer (WL3100). After the transducer calibration has been verified, the system can be returned to normal operation by :
Remove the pump up calibrator from the Bubble Rate Test Port Set the “Calibrate Valve” back to the Open position. Set the “River Line Select” valve back to the Open Position.
Gas Purge Compressor © Copyright
Air Force 100-9 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
4.2
Startup Sequence
After power-up the status LED flashes all 3 colours, Green then Red then Blue then all 3 colours together to confirm the LED is working OK. The HS40 then enters a tank pressurization check.
4.3
Tank Pressurisation
When the tank pressure falls below 400kPa (58psi), the compressor will start and pump the pressure back up to 750kPa (110psi). (While the compressor is on, the LED will be steady blue. At the end of the pump up cycle, the LED will flash green if completed successfully, or flash red if there is a problem.)
4.4
Tank pressure kPa (psi) 750 (110)
Compressor on
400 (58)
Time
Battery Size
The HS40 consumes a quiescent of about 7mA and draws about 15A for 1 min every 18 hours when the rate at the test orifice is set to 26 bubbles/min (equiv sight glass rate of 100 bubbles/min @10 mH2O) This averages to 15A x 1min / (18hr x 60min/hr) = 13.9mA. The total average current is therefore: HS40 quiescent HS40 Compressor average WL3100 average Total consumption
7.0mA 13.9mA 3.3mA ===== 24.2mA
A 38Ah battery will run for 38Ah / 24.2mA = 1570 hrs = 65 days = 2 months (without any solar or additional charging) The battery endurance will be dependant on the following: The consumption of other equipment connected to the battery. The frequency that the system wakes up to take a measurement. The length of time the system is awake for each measurement. The selected bubble rate – the higher the bubble rate, the more often the compressor will be required to replenish the tank. The battery Ah capacity – the minimum recommended battery capacity is 18Ah. (Use the above method to estimate the battery endurance.)
Gas Purge Compressor © Copyright
Air Force 100-10 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
4.5
Battery Indication
The battery voltage is monitored during all phases of operation. If the battery voltage falls below 10.0V then the status LED will show the battery low indication and all compressor operation will stop immediately. The battery voltage must then rise above 12.0V before clearing the battery low condition. (The 10V limit was 11V in units prior to S/N 10-142) Mains or Solar Charging
Batt V 12.0V 10.0V Battery OK Green LED
Battery Low Red LED
Battery OK Green LED
A green LED flash indicates the battery is OK, a red LED flash indicates the battery low indication has been tripped. Once the battery voltage rises above 12.0V the battery low condition will be cleared and the status LED will return to a green flash. A pump up cycle will be aborted if a battery low condition occurs. This condition is most likely to occur when the compressor is on because it draws approximately 15A when operating – causing the battery voltage to drop. A compressor soft start feature was added to units with S/N 10-142 and higher, which allows the compressor to slowly ramp up to speed, limiting the initial peak current draw which always occurs when motors start up. This also helps prevent a battery low condition being registered as the compressor starts.
Gas Purge Compressor © Copyright
Air Force 100-11 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
5.
Maintenance
The HS-40 is almost maintenance-free. You will need to ensure that your battery / power supply is sufficient for the equipment that you have installed. (See Specification page). As the pump’s duty cycle is only about a minute every 18 hours, it will last for many years. All fittings must be secure. Even a tiny leak will prevent the pressure from being maintained. The air dryer features an auto drain moisture trap. When the trap senses moisture build up, a relief valve is opened and the moisture is purged under pressure to atmosphere. Check the battery connections are free from corrosion – clean, wipe with Vaseline/grease and reconnect fittings, doing up tightly.
6.
Fault Finding
HS-40 Not Powering Up
Check battery voltage – should be above 12V DC. Check battery POWER and GROUND connections to the battery – make sure they are done up tightly and there is no corrosion.
Compressor not operating – and tank pressure is below 400kPa (58psi)
Check compressor connections to HS-40 controller. Check battery voltage is greater than 12 volts before the tank re-pressurise cycle. (If status LED is flashing red, then the battery voltage is too low and it will not attempt a tank re-pressurisation until the battery voltage rises above 12V) Check if battery voltage drops during the tank re-pressurise cycle. (Battery may require charging) (If using a power supply instead of a battery, it may be going into current limit with the compressor start current) If the status LED is flashing blue fast, then the compressor duty cycle of 10% has been exceeded. Wait for 30 mins and the compressor will automatically start and repressurise the tank.
Compressor Starts BUT Tank pressure is not reaching the required 750kPa (110psi)
Make sure the control valve is not in the “Purge” position. Pressing the blue button will stop the compressor during a pump up cycle. Check the battery voltage is sufficient to operate the compressor. The battery voltage should be around 12V – even when the compressor is on. Check the battery connections – the compressor draws about 15A and so a loose connection will stop the compressor from reaching its full pumping capacity. Check the internal tube connections for leaks by spraying a bubble solution on all internal fittings. Tighten or repair the leaking fitting. (This will require the control knobs and the bubble rate knob to be removed - the front panel can be opened by
Gas Purge Compressor © Copyright
Air Force 100-12 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd removing the 4 front panel corner screws and hinging to the right.)
The LED is flashing Red
The battery voltage has fallen below 11V DC – probably during a pump up cycle. Charge the battery to a level above 12V and the LED will flash green (normal).
The LED is flashing Blue
If the LED is flashing blue slowly, the previous pump up cycle did not reach the required 750kPa (110 psi). This could be due to either the battery voltage too low to prevent the compressor from running properly or there is a leak in one of the pressure fittings. If the LED is flashing blue fast, the compressor duty cycle of 10% has been exceeded. This is probably due to several purges being performed in a row, which causes to compressor to run for more than 3 minutes. The system will automatically wait for 30 minutes for the compressor to cool down, and then complete the pump up cycle.
Gas Purge Compressor © Copyright
Air Force 100-13 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
7.
Specifications
Power : Operating Voltage : Recommended Battery :
12V DC Nominal 12V DC Sealed Lead Acid (38Ah) (10 bubbles/min, site glass equivalent 40 bubbles/min @ 10mH20 will provide approx 100 days continuous Operation, without any solar charging, using GCO1-P orifice)
Minimum Battery Size : Low Battery cut-out : Battery recharge recovery :
12V DC Sealed Lead Acid (18Ah) 10.0 V DC (This was 11V in units prior to S/N 10-142) 12.0V DC
Operation Range : Electronics Quiescent : Compressor Current :
Up to 30m (100ft) of water pressure head 7 mA 15 Amps (for 1 min every 18 hrs, 26 bubbles/min, site glass equivalent 100 bubbles/min @ 10mH20) (Compressor soft start in units with S/N 10-142 and higher)
Average battery consumption :
24.2 mA(with bubble rate set to 26 bubbles/min @ 10mH20)
Solar :
A small 10Watt solar panel is sufficient to keep the battery fully charged.
Maximum Tank/Purge Pressure : Minimum Pump/Purge Pressure :
750 kPa (110 psi) 400 kPa (58 psi)
Differential Pressure :
20kPa (3psi) to 35kPa (5psi)
Bubble Rate :
Adjustable from 0 to >300 bubbles/min, site glass equivalent
Transducer Pressure Connection :
1/4 inch tube
River Line Connection :
3/8 inch tube, Dual orifice (2) x 3/8 inch tube
Max River-line Length :
200m (600ft) using 3/8 in OD and 1/8 ID tubing
Air Dryer :
5 year maintenance free “Self Purging”, Hydrophobic filter
Operating Temperature Range :
-40oC to +70oC HS-40 and HS-40/3100A -20oC to +70oC HS-40/3100
Enclosure :
Zinc plated steel enclosure, powder coated grey
Enclosure Size :
400mm x 300mm x 180mm (H x W x D) 16 inch x 12inch x 7 inch
Weight (with built-in WL3100) :
12 kg (26.5 lbs)
Gas Purge Compressor © Copyright
Air Force 100-14 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Appendix A
WL3100 Operation Manual
Operation The WL3100 Multi Output Dry Transducer powers up and takes a measurement at the following times :
When the “Level” is displayed on the LCD, a reading is taken every 12 seconds and the Level on the LCD is updated.
When the 4-20mA current loop has power applied, a reading is taken every 12 seconds. The 4-20mA current loop is updated at the same time.
When the SDI-12/RS232 interface requests a measurement using the ‘M’ or ‘C’ commands.
When the LCD menu “Continuous Meas” is set to YES, measurements are continuously taken.
External Power The WL3100 requires an external power source of +12VDC (9.6V to 16VDC) connected via the SDI-12 port. The 4-20mA current loop circuitry is optically isolated from the measuring and SDI-12 electronics, therefore separate loop power must be provided by the telemetry or data logging equipment. LCD Screen There are 7 main LCD screens available. Some screens display internal data and some allow parameters to be changed. The screens are : LCD Screen WL3100 S/W 7.2 Level : 5.127m Sensor Addr : 2 Sensor ID : 8-123 Comms Type : SDI-12 4mA / 20mA Level : 0.0m / 10.0m Set Level : 5.127m Calc Offset : 0.003m Sampling Mode : Single
Gas Purge Compressor © Copyright
Description Display model, S/W Rev and Water Level Display sensor SDI-12 address and 5 digit ID Display type of communications SDI-12 or RS232 Indicates the 4mA Level and the 20mA Level Allows the present River Level to be preset – internally calculates an offset Displays the internally calculated offset Contin+Avg 5 => the river level is continuously measured and the last 5 values are averaged. Single=> the river level is only measured when requested.
Air Force 100-15 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd There are many other menu screens that allow the fine tuning of calibration if this is required. The following menu tree should be examined carefully before embarking through it. (The “scroll” button steps down to the next screen or changes the value if it is flashing, and the “select” button allows you to enter the edit mode. (5 secs) means hold the “select” button for 5 secs to enter this menu.)
Gas Purge Compressor © Copyright
Air Force 100-16 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Configuring the WL3100 1. If using the SDI-12 interface, set the required address by stepping to the “Sensor Addr” menu, and pressing the “Select” button and then use the “Scroll” button to set the address from 0 to 9. 2. If using an SDI-12 logger, make sure the “Comms Type” is set to SDI-12. If using an RTU with an SDI-12 to RS232 adapter then set the “Comms Type” to RS232. 3. Use the staff gauge in the river to measure the water level (1.450m) 4. Step to the “Set Level” menu and set it to 1.450m *** If operating in SDI-12 mode, setup is complete. ***
If operating in 4-20mA mode then continue with step 5. 5. Estimate the range over which the water level will change. (eg. Min level = 1.000m : Max Level = 8.000m) 6. Step to the “4mA / 20mA Level” menu Set the 4mA level to 1.000m Set the 20mA level to 8.000m When the water level is at 1.000m the 4-20mA current will be 4.000mA When the water level is at 4.500m the 4-20mA current will be 12.000mA When the water level is at 7.000m the 4-20mA current will be 20.000mA 7. The range in this example is 8.000 – 1.000 = 7.000m Set the logger range to 7.000m (eg. ML420 range is set with TxR=7.000) 8. The offset in this example is 1.000m Set the logger offset to 1.000m (eg. ML420 offset is set with RvHR=1.000) 9. Set the logging interval and transducer warmup period in the data logger. There are 2 ways to set the transducer warmup period – if “Continuous Meas?” is set to “Yes”, then the warmup can be set as low as 1 sec. (Slightly more power is drawn in this mode as the WL3100 continually takes measurements.) If however, “Continuous Meas?” is set to “No”, then the warmup must be set for about 15 secs. (eg. Say ML420 interval is 15mins and warmup is 1 sec then TXI=015/01 ) NOTE :
Setting the 4-20mA range to the smallest possible will give the best resolution on a 4-20mA interface !
Gas Purge Compressor © Copyright
Air Force 100-17 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Sampling Mode – Single, Continuous, Averaging In S/W Rev 7.1 and lower, the last menu item shown on page 12 is “Continuous Mode ?”. This could either be set to YES or NO. When “Continuous Mode” is set to “NO” the WL3100 only takes a sample when : 1. The water level is displayed on the LCD or 2. An SDI-12 Measure command is received or 3. The 4-20mA loop power is detected. When “Continuous Mode” is set to “YES” the WL3100 takes a sample : 1. Every 12 secs. (Continuously) (This is useful if you use the SDI-12 command 0R0! as it will immediately return the most recent measurement made within the last 12 secs – which makes the WL3100 SDI-12 interface the same as the AD375A SDI-12 interface. It can also be useful when using the 4-20mA interface, as the 420mA loop current will be accurately updated 100mS after loop power is applied – without having to wait 12 secs for a measurement to be made !!)
In S/W Rev 7.2 and higher, the last menu item shown on page 12 is “Sampling Mode”. This could either be set to Single, Contin+Avg 1, Contin+Avg 2,……..., Contin+Avg 20. When “Sampling Mode” is set to “Single” the WL3100 only takes a sample when : 1. The water level is displayed on the LCD or 2. An SDI-12 Measure command is received or 3. The 4-20mA loop power is detected. When “Sampling Mode” is set to “Contin+Avg X” the WL3100 takes a sample : 1. Every 12 secs. (Continuously) (When a sample is requested, via the display or via SDI-12 or 4-20mA, the last X samples are averaged. If it is known that the water level will change very slowly, it is advantageous to set X to a high number, so that the last say 20 samples will be averaged. Note that 20 samples will take 20 x 12secs = 240 secs = 4 mins. (So the water level is averaged over a 4 minute period) If it is known that the water level changes rapidly, then it would be better to set X to a low number, so that say 2 samples will be averaged.) The “Contin+Avg 1” mode only averages 1 sample, which at first appearance doesn’t seem to be very useful – this was included to give the same operation as the above described “Continuous Mode” set to “YES”. (Read the description above to see why this mode is useful.)
Gas Purge Compressor © Copyright
Air Force 100-18 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Averaging The following diagram shows what happens when the WL3100 is set to average “5 samples”. (When in average mode, the WL3100 takes a sample every 12 secs (Each circle represents a “sample” that is a highly filtered, 24 bit high accuracy, temperature compensated value !) 12
Sampl
Sampl e
Reply is the average of the previous 5
Sampl e
Sampl e
Reply is the average of the previous 5
Reply is the average of the previous 5
When a sample is requested (via the LCD, SDI-12 M command or 4-20mA), the next periodic sample will reply with an average of the previous 5 samples (obviously the number of samples used to calculate the average will depend upon the setting selected - between 1 and 20). (If the SDI-12 0R0! command is used, then the samples immediately prior to the command being received are used to perform the average !)
Gas Purge Compressor © Copyright
Air Force 100-19 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd RS 232/SDI-12 Selection The SDI-12 protocol has very strict timing requirements. The operator may use the SDI-12 to RS232 adaptor cable and then communicate using RS232 from a PC. The “RS232" option must be selected via the LCD and pushbuttons. In this mode all of the timing/break requirements of the SDI-12 are removed. Commands may be typed from a terminal program such as “Hyperterm”. *** Note *** You must use 1200 baud, 7 bits, even parity and no handshaking. If using an SDI-12 logger you must select the SDI-12 option via the LCD and pushbuttons.
SDI-12 V1.3 Compliant Command Set
(CRC commands are implemented)
(Please note the letter ‘a’ in the commands below refer to the SDI-12 address 0, 1, 2,….9) Name
Command
Response
Break
None
Acknowledge Active
Continuous spacing for at least 12 milliseconds a!
Send Identification
aI!
Change Address
aAb!
allccccccccmmmmmmvvvxxx...xx (Refer Note 1.) b
Address Query
?!
a
Start Measurement
aM!
Send Data
aD0!
Continuous Measurement
aR0! or aRC0! aV!
Start Verification Start Concurrent Measurement
aC!
or
or
aMC!
a
atttn
(Refer Note 2)
a or a a (Refer Note 3) a atttn aCC!
atttnn
(Refer Note 2)
Note 1. a13HydrServWL31005.112345 -- ------------ --------- --- -----| | | | | | | | | | | --5 digit Sensor ID (eg 12345)(as set in aX4 command) | | | | --------S/W Revision (eg 5.1) | | | ---------------Model (WL3100) | | ---------------------------Company ID (HydrServ) | -----------------------------------SDI-12 Version V1.3 Compliant -------------------------------------Unit Address Note 2. The measurement command “M” and the concurrent command “C” will both return a time “ttt” of 012 indicating that the measurement will be ready in 12 seconds. Do not request data within this 12 second window, or an empty reply will be received. (In accordance with the SDI-12 protocol.) When an “M” command is in progress, the dry transducer will issue a service request “a” when the measurement is complete and ready for a data request. (Again, in accordance with the SDI-12 protocol) Note 3. The Continuous Measurement command returns the present River Level. If the LCD command “Continuous Meas ?” is set to “Yes” then the river level is continuously measured when 12V is present and so the aR0! returns the river level without having to issue an aM! Measure command. Gas Purge Compressor © Copyright
Air Force 100-20 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd *** PLEASE NOTE *** For more information on SDI-12 commands, go to the www.sdi-12.org website and download the “SDI-12 Protocol Specification” available on the home page.
Special Commands The following commands conform to the SDI-12 protocol, and allow specific parameters within the WL3100 to be configured. Care should be taken with some commands, as they may destroy the factory calibration.
aXn!
Return data associated with command ’n’. The multi output dry transducer will reply with a0001 The aDO! command must be issued to get the actual data.
aXn+xxxx!
Set parameter for command ‘n’. The multi output dry transducer will reply with a0001 The aDO! command must be issued to get the actual data.
Set/Get Current Value aX0! Get the river level (River level from last measurement). aX0+0012.345! Set the river level to +12.345 m (or ft).
Get Multi Output Dry Transducer Pressure aX1!
Get the Pressure. eg. +0004.524 psi (or kPa)
Get/Set the 4mA Level aX2! aX2+0002.5!
Get the 4mA Level. Sets the 4mA Level to 2.5m (or ft) When the water level is 2.5m then the 4-20mA loop will pass 4mA
Get/Set the 20mA Level aX3! aX3+0020.0!
Get the 20mA Level. Sets the 20mA Level to 20.0m (or ft) When the water level is 20.0m then the 4-20mA loop will pass 20mA
Set/Get ID Number aX4! aX4+12345!
Get the dry transducer ID. Set the dry trasnducer ID. Acceptable values 0-65535. This value appears in the Identify command.
Set/Get the User Factor aX7! Get the User Factor. aX7+0.705373! Set the User Factor to 0.705373 m/psi
Gas Purge Compressor © Copyright
Air Force 100-21 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
WL3100 Field Setup Procedure 1.
Press either of the two push buttons on the dry transducer to activate the LCD display.
2.
Use the scroll button to scroll through the menu to “Set Level” and press the select button.
3.
Use the select button to move the blinking cursor to the desired digit position (that needs to be changed), and use the scroll button to increment the value. When the rightmost digit is at the desired value press the select button to save the value. Press select button again to start with the left most digit again.
4.
After the select button is used to save a value ie. Water level, then pressing the scroll button will continue to step you through the menu as before.
5.
The 4-20mA current loop will be continuously updated as the various parameters are changed.
6.
The 4mA water level and the 20mA water level can be set separately. (See the menu tree structure in the LCD Operation section)
7.
The various parameters may also be set by the SDI-12 “special command” set, via the SDI-12 Input connection, or the RS-232 connection if a laptop is available using a simple terminal emulation program whereby ASCII characters are typed (adhering to the SDI-12 Ver 1.3 protocol). Note: If the commands are being typed by the operator, the “Comms Type” must be set to RS232. In this mode the strict SDI-12 timing is ignored. An adapter cable needs to be used in this mode. See the SDI-12 to RS232 Interface drawing at the end of this Appendix for details.
Gas Purge Compressor © Copyright
Air Force 100-22 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd WL3100 Wiring Details Screwless Terminals The WL3100 electrical connections are made on a plug in terminal block underneath the HS40. The plug in terminal block shown is a screwless terminal that keeps a constant tension on the wire that is inserted. 1. Use a small flat blade screwdriver and push-in on the orange groove. Multimeter probe can be inserted here !!!
2. Insert the stripped wire here. 3. Release the orange part to put secure the wire. 4. Pull on the wire to make sure it is secure.
External Power
The WL3100 will only be able to make a water level measurement if +12VDC (9.6V to 16VDC) power is connected. An adequate 12VDC (9 to 30VDC) battery and charger option should be used if the optically isolated 4-20 mA current loop is to be powered continuously and independently of the telemetry module or data logging equipment. The easiest way to see if +12V is present is to press one of the WL3100 buttons and check that the backlighting comes on. SDI-12 Data 0V
To data logger
+12V
0V
Gas Purge Compressor © Copyright
Air Force 100-23 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd 4-20mA Interface The 4-20mA interface in the WL3100 is optically isolated from the 0V and +12VDC on the right hand end of the connector. The 4-20mA circuitry must be powered by the loop. There are 2 ways to take 4-20mA measurements : 1. “Continuous Meas” set to Off (S/W Rev 7.1 and lower) “ Sampling Mode” set to Single (S/W Rev 7.2 and higher) When the WL3100 detects loop power, it initiates a water level measurement – this takes 12 seconds – the 4-20mA current is updated at the end of the measurement and the data logger can measure the current. Therefore the data logger must be set for transducer “warm-up” of about 15 secs. 2. “Continuous Meas” set to On (S/W Rev 7.1 and lower) “Sampling Mode” set to Contin+Avg X (S/W Rev 7.2 and higher) The WL3100 is set to take a measurement continuously (every 12 secs). When the WL3100 detects loop power, it updates the 4-20mA current within 100mS - with the water level previously measured within the last 12 secs. Therefore the data logger can be set for a transducer “warm-up” of about 1 sec. The following diagram shows how the 4-20mA interface must be loop powered. (This example uses the Hydrological Services ML420 Data Logger.)
+ 4-20mA
Batt +12V
- 4-20mA
Batt 0V -
+ 12V Battery
ML420 Data Logger
WL3100 Connections
Sense ML420 Data Logger measuring the 4-20mA
To conserve power, the data logger switches power to the 4-20mA circuit only when it wants to make a measurement. PLEASE NOTE : The SDI-12 interface and the 4-20mA interface can be used at the same time by 2 different devices. For example, a data logger can be connected to the SDI-12 interface while an RTU is connected to the 4-20mA interface !!! Gas Purge Compressor © Copyright
Air Force 100-24 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Fine Tuning The WL3100 Software Rev 6.5 has many enhancements to improve the performance. These include : Measures pressure in psi or kPa - factory calibrated. Displays water level in m or ft. User scaling factor to take into account local conditions such as gravity, water density, etc. Ability to calculate gravity, water density, air density and user factor. Factory calibration of the 4mA and 20mA current end points. Adjustable 4mA and 20mA water levels. Negative levels for the 4mA and 20mA levels - to match the site gauge readings. Display of the internally calculated water level offset + ability to zero this offset if required Update the 4-20mA current within 100mS of detecting loop power SDI-12 Version 1.3 compliant with CRC The WL3100 measures gauge pressure and applies temperature compensation to correct for errors in the transducer. The measured pressure is converted to a water level through a “User Factor”. Adjustment of this “User Factor” allows for variations introduced by the equipment location in the world, as well as local conditions.
Water Level = Pressure x User Factor + Offset
The User Factor is a function of gravity, water density, air density, equipment height above the orifice, and nominal water level. (Note that gravity is itself a function of latitude and altitude) (Note that water density is a function of water temperature) (Note that air density is a function of altitude) The User Factor may be entered directly into the WL3100, or it can be calculated internally by entering the information listed above (for the WL3100A only). (See the Menu Tree in the LCD Screen section) Various combinations of information may be entered, depending on what is known. For example, the operator could enter the gravity directly - or alternatively the latitude and altitude could be entered and the WL3100A will calculate the gravity for you. The WL3100 can be configured to measure pressure in psi or kPa - and it can be configured to measure the water height in m or ft. The User Factor is automatically corrected to account for any change in units. Typical errors that are introduced by the above factors are demonstrated in the graphs on the following pages.
Gas Purge Compressor © Copyright
Air Force 100-25 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Gas Purge Compressor © Copyright
Air Force 100-26 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
4-20mA Level The 4-20mA Level parameters in the enhanced WL3100 sets the water level required to make 4mA and 20mA appear on the 4-20mA interface. That is : Water Level 4mA Level 20mA Level
4-20mA Current 4.000mA 20.000mA
These levels may be changed by the user by : 1. Use the scroll button to view the 4-20mA Level menu item. 2. Press and hold the select button for 5 seconds until Set 4mA Level appears. 3. Press the select button to make the first digit flash. 4. Press the scroll button to change it. Press select for the next digit etc. 5. When the 4mA Level is complete, press scroll to select the 20mA Level. 6. Repeat steps 3 and 4 to change the 20mA Levels. Calculated Offset When the “Set Level” function is performed (see the standard manual), the WL3100 calculates an offset between the measured water level and the desired water level. That is : Displayed (desired) Water Level
=
Measured Water Level + Calculated Offset
This calculated offset can now be viewed in the “Calc Offset” menu. (This is for reference only, and serves no other purpose) If the user wishes to force this offset to 0, then simply press and hold the “select” button for 5 seconds while “Calc Offset” is displayed.
Gas Purge Compressor © Copyright
Air Force 100-27 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
SDI-12 to RS232 Interface The following schematic is for an SDI-12 to RS232 adapter that can be used for any Hydrological Services SDI-12 transducer. The adapter will allow an SDI-12 transducer to be connected to a PC, and will communicate on an RS232 port at 1200 Baud, 7 bits and even parity using an application such as HyperTerm or similar.
Gas Purge Compressor © Copyright
Air Force 100-28 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Appendix B
Installing Polyethelene Tubing and Orifice Fittings
General The polythene tubing - SC078-01 is provided in three hundred metre rolls. It is an extremely durable material that has been used successfully in this application world wide for many years. The tubing is flexible, easy to handle and can be cut with a knife. The orifice fitting is comprised of a moulded polythene threaded cap, an orifice outlet and a tube fitting. The moulded cap will screw onto a standard 50 nominal bore galvanised pipe. Orifice Fittings The site and reference level for the orifice fittings should be resolved before installation proceeds. The length of tubing from the HS55 to the orifice should not exceed 150 metres. A suggested method for installation of the orifice fitting is shown below. The site of the orifice should be positioned in quiet water out of the mainstream to provide protection. The area should be free of silting and aquatic growth. The mounting for the orifice fitting should consist of a section of 50 nominal bore galvanised pipe threaded at one end and secured at the appropriate reference level. The securing of the orifice mounting should be such that it can withstand the forces applied by the flowing stream and associated floating debris. Preparation of Orifice Tubing Do not open the carton or remove the strapping. To prepare the roll of tubing for use, cut a 300 mm diameter hole in the centre of the cardboard carton, retrieve the end of the tubing from the middle of the coil, then cut the strapping retaining the coil. This method will reduce the possibility of tangling the tubing. Prevent the ingress of dirt etc. from entering the tubing, by taping up the ends. At no time should the open end of the tubing be permitted to contact the soil. Orifice Tubing It is recommended that a trench be dug (minimum 600 deep) between the equipment shelter and the proposed positions of the orifice The trenches should not have any low points in their length, they should have a continuous fall to the river. Pull the free end of the coiled tubing to the orifice position laying the tubing in the trench as you go. Refer to diagrams below Remove the protective tape from the end of the tubing, and push the tubing through the 50 nominal bore pipe mounting. Insert the tubing into the tube fitting on the rear of the orifice fitting, ensuring that both ferrules are in place. Tighten the fitting nut. (Refer to the following diagram for tightening procedure). Place the orifice fitting onto the mounting pipe and tighten. Cut the tube at the coil end (tape both ends), ensuring that there is sufficient length to make the joint at the HS40 within the shelter. Check the lay of the tubing in the trench to ensure that it is free of coils and kinks. Under no Gas Purge Compressor © Copyright
Air Force 100-29 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd circumstances should the tube form hollows where moisture can be trapped within the tube. Lay the tubing into position in the equipment shelter as required. Remove the protective tape from the end of river line tube. Insert the end of the tube into the appropriate river line fitting on the HS55 and tighten both fittings. (Refer to diagram for tightening procedure). Open the valve to the orifice.
Gas Purge Compressor © Copyright
Air Force 100-30 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Appendix C
Using Pressure to Measure Water Level
Gas Purge Principle The behaviour of a gas flowing under a variable back pressure is utilised as an accurate means of measuring liquid head. Provided that: 1. The density of the gas is nearly the same as air 2. The velocity of gas is low enough so as not to produce significant pressure drop down the line then the system pressure will be equal to the back pressure. This principle is illustrated in the following series of diagrams. In the first example, the tube exhausts to atmosphere and hence the water manometer indicate zero pressure in the system because it is acted on by two equal pressures- the system pressure and the atmospheric pressure
Fig.1 - Depicts first stage in application of gas purge principle
Fig.1 also illustrate another feature of all pressure systems, namely the gas endeavours to escape through any material that it is in contact with to find a lower pressure, but for practical purposes, the system pressure reflects the lowest of the outlet pressures. In this case, gas endeavours to pass through the walls of the tubing and fittings, through the water, but elects to take the easier path to atmosphere, which is in effect a “massive leak”.
Gas Purge Compressor © Copyright
Air Force 100-31 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Therefore, it follows that in any pressure system that can exhaust to atmosphere, either through a valve or by a large leak, the system pressure is atmospheric and will not reflect any other pressure. Provided air or a gas that has a very similar density to air is used, then the errors from this source can be neglected. Nitrogen is preferred as it does not promote the formation of aquatic growth. The effect of the velocity of the gas can be observed by opening valve A, a higher pressure will be needed to force a high volume of gas through the line, resulting in a pressure drop between valve A and the outlet. Depending on the location of the manometer connection, the manometer will reflect a proportion of this increase in pressure.
Fig. 2 – High gas flow * Refer “Bubbler System Instrumentation for Water Level Measurement” - Report of Investigation No. 23 state of Illinois, U.S.A
Head To Pressure Conversion As we are not seeking to measure atmospheric pressure, but liquid head, how is the principle applied ? Simply by using two physical characteristics. 1. The tendency of the gas under pressure to “seek” a lower pressure. 2. The ability of a gas to “pass through” liquids. The first characteristic has already been demonstrated. The second characteristic can be appreciated by blowing through a hollow tube (straw) that is immersed in water. No bubble will appear until the pressure in the tube is sufficient to expel all the water from the tube.
Gas Purge Compressor © Copyright
Air Force 100-32 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Fig 3.
I. II.
III.
If a tube is immersed in a liquid, it can be seen that the pressure at the bottom of the tube is that exerted by the head of liquid above it. If we connect a gas supply to the tube, the gas will act on the surface of the liquid in the tube and tend to force it down. Assuming there is no change in level, the pressure at the end of the tube must be still the same. If we increase the pressure so that the gas can push out all the liquid against pressure level A, then it follows that the pressure at A will be the back pressure in the system. Also the pressure of each bubble of gas as it emerges from the end of the tube will a that point have an internal pressure equal to the head, and this internal pressure reduces until the bubble emerges at the surface at atmospheric pressure.
Therefore the gas acts like a plunger to keep the water out of the tube and in effect, precisely balances the head of water that would naturally occur if the tube was opened to atmospheric pressure. In other words, the system pressure (back-pressure) is supporting a column of water, equal to the pressure head. Hence, any pressure measuring device, if connected to the pressure system will record the pressure head over the tube outlet (orifice).
Fig. 4 depicts a water manometer connected to the system and it is recommended that such an arrangement be set up in a workshop for staff training.
Gas Purge Operational Characteristics In the foregoing, the discussion has been limited to static head conditions, whereas in practice, the levels in stream are constantly fluctuating. Gas Purge Compressor © Copyright
Air Force 100-33 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
“Rising” Situations It is the “rising” or “increasing head” situation that is critical for the correct operation system. Consider a situation where the gas supply is cut off and the level rises- refer Fig.5.
Fig.5 - With gas supply cut off. Head increased from H1 to H2, gas is forced down the tube by an amount X.
In this situation, it can be seen that whilst the system pressure has increased, it is not equal to the new head H2, but rather H2-x. This condition will remain as long as the gas is shut off. In other words, we now have a “closed” system, which respond to changes in accordance with universal gas lawPV i i a constant Ti To revert back to the open system, we must restore gas supply, which will eventually build up pressure in the system, until the gas escape from the orifice and the system pressure again becomes the precise head measurement. The time taken for the pressure system to respond to a given head pressure is commonly referred to as “follow rate”. The normal procedure is to establish the maximum rate of rise to be measured and adjust the gas flow so that there is no significant lag in the pressure system. However, in order to conserve the gas supply, the flow rate (bubble rate) is set to the minimum that will meet these conditions.
“Falling “ Situation The “falling” situation is of course the reverse of the rising situation except that there is now excess pressure in the system. If we were to suddenly lift up the orifice in Fig. 4, the pressure would drop to the new head, seen by the sudden rush of bubbles. Accordingly, even the lowest bubble rate will suffice for falling conditions. In practice, it may take some time to the pressure to “bleed” away”, but this is usually less than the response time of the sensing unit.
Gas Purge Compressor © Copyright
Air Force 100-34 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Field Requirement of Gas Purge Systems The principle requirements of gas purge areI. a fine metering valve and sight feed for accurately setting the bubble rate. II. Constant regulator to maintain a constant bubble rate with changes of head. III. Pressure connections and valves for connecting the tubing to the river and the instrument. With the overall provision that the unit must be “leak proof”, otherwise the true head will not be recorded. The configuration most widely used is shown in Fig 6.
Fig. 6 - Diagramatic view of field gas purge, single line without purge facilities.
Dual Line Connections For long line, the effect referred to in Fig.2 becomes significant and it is usual to make the connection to the system near the orifice, so in effect there are two lines running the orifice. Hence the term dual line. The operation of Hydrological Services units is described in more details in diagrams 15 and 16 of “instruction Manual for Sherlock Pressure Sensing Units”.
Gas Purge Compressor © Copyright
Air Force 100-35 Issue 1.11
13/6/2012
Hydrological Services Pty Ltd
Pressure Bulb or Closed System The pressure bulb system relies on the normal under pressure.
PV i i = constant relationship for gases Ti
Using similar diagrams to before, the closed system can be illustrated follows:-
Fig. 7- Atmosphere- up to the level at which the water seals off the bottom of the bulb.
Fig.8 - water seals off air and at this point system pressure is still atmosphere.
Fig. 9 - system operating under head conditions Gas Purge Compressor © Copyright
Air Force 100-36
Issue 1.11 13/6/2012
Hydrological Services Pty Ltd
As the water rises, the system pressure increases to the equivalent of the head H minus the amount the water rises within the bulb. This amount x, is non-linear and therefore cannot be completely compensated for by simple calibration. Provided the head H does not fall below say 300 mm, error from this cause is minimal. Basically the closed system will give good results subject to gradual changes of water temperature being experienced and the system being completely gas tight. A full discussion of this principle in given in “Low Cost Stream Height Recorders” Unisearch (N.S.W) publication.
Gas Purge Compressor © Copyright
Air Force 100-37
Issue 1.11 13/6/2012
Hydrological Services Pty Ltd
Appendix D
HS-40DO (Dual Orifice)
Features of Dual Orifice The Model HS-40DO comes with a dual orifice application. It consists of 2 orifices located at different heights from the river bed. Under normal conditions the bottom orifice is active and the top orifice is inactive. The dual orifice application become beneficial in a situation where severe siltation appears and causes the blockage of the bottom orifice at which instance the valve of the bottom orifice (1) is closed and the valve of the inactive (top) orifice (2) is opened to keep the bubbler system operating.
Orifice 1
Orifice 2
Note: Only one orifice can operate at a time. If the level of the second orifice exceeds the range of the transducer; the transducer level can be set again at the second orifice.
Gas Purge Compressor © Copyright
Air Force 100-38
Issue 1.11 13/6/2012
Hydrological Services Pty Ltd
Appendix E Gas Chamber Orifice Assembly Step 1: Secure Socket/Locknut to the 2” BSP pipe
2” BSP THREADED PIPE
Step 2: Undo the nut and ferrules; feed the tube nut and the two ferrules onto the river line as shown in figure below
Step 3: Tighten the tube nut to the GCO1 fitting as shown in figure below
Gas Purge Compressor © Copyright
Air Force 100-39
Issue 1.11 13/6/2012
Hydrological Services Pty Ltd
Step 4: Place the GCO1 assembly onto the mounting pipe, adjust coupling so the GCO1 is horizontal to the water, and tighten the flexible coupling with GCO1 in position.
30
Note: Ensure that the GCO1 is horizontally level as shown. Flexible coupling allows adjustment up to 30 degrees.
(L) 2” Galvanised Pipe
Flexible Coupling
GCO1 Body Volume = 2000 ml
(H)
Tube Nut River Line Tube
Back Ferrule
Front Ferrule
Orifice fitting
Revolving Screen (for cleaning Purposes) (D)
GCO1 DIMENSIONS Dimension
Metric (mm)
Imperial (inch)
L
410
16.2
D
210
8.3
H
110
4.3
Gas Purge Compressor © Copyright
Air Force 100-40
Issue 1.11 13/6/2012
Hydrological Services Pty Ltd
Typical installation for HS-40 & HS-40DO (Dual Orifice) Antenna + Antenna Bracket
Hut
10 Watt Solar Panel
Voltage Regulator Data Logger
12VDC Battery 38 AmpHr 3/8” River Line Tube
Gas Chamber Orifice Model GCO1P with adjustable coupling
HS-40 Typical Installation
Gas Purge Compressor © Copyright
Air Force 100-41
Issue 1.11 13/6/2012
Hydrological Services Pty Ltd
Antenna + Antenna Bracket Hut
Valve (1) of Orifice (1) Valve is open Valve (2) of Orifice (2) Valve is closed
10 Watt Solar Panel Voltage Regulator Data Logger 12VDC Battery 38 AmpHr
Note: Only one orifice in use at a time 2 x 3/8” River Line Tube Gas Chamber Orifice Model GCO1P with adjustable coupling Orifice 2 Inactive
Orifice 1 Active
HS-40DO Typical Installation
Gas Purge Compressor © Copyright
Air Force 100-42
Issue 1.11 13/6/2012
