Table of Contents
Contents Executive Summary ............................................................................................................. - 3 Introduction ........................................................................................................................ - 4 Design Specifications ........................................................................................................... - 4 Function/Performance ............................................................................................................ - 4 Product Cost ............................................................................................................................ - 5 Delivery Date........................................................................................................................... - 5 Quantity .................................................................................................................................. - 5 Environmental Issues .............................................................................................................. - 5 Quality ..................................................................................................................................... - 5 Energy Consumption ............................................................................................................... - 6 Reliability................................................................................................................................. - 6 Maintenance ........................................................................................................................... - 6 Mechanical Loading ................................................................................................................ - 6 Size .......................................................................................................................................... - 7 Weight ..................................................................................................................................... - 7 Spatial Constraints .................................................................................................................. - 7 Aesthetics ................................................................................................................................ - 7 Transportation and Packaging ................................................................................................ - 7 Personnel ................................................................................................................................ - 8 Service Life .............................................................................................................................. - 8 Noise Radiation ....................................................................................................................... - 8 Operation Instructions ............................................................................................................ - 8 Human Factors ........................................................................................................................ - 8 Health Issues ........................................................................................................................... - 8 Government Regulations ........................................................................................................ - 9 Shelf-Life Storage .................................................................................................................... - 9 Operating Costs....................................................................................................................... - 9 Environmental Conditions ...................................................................................................... - 9 Design Specification Weighting Factors ............................................................................... - 9 Conceptual Design Concepts.............................................................................................. - 11 -1-
Drive Design Concept 1 ......................................................................................................... - 11 Drive Design Concept 2 ......................................................................................................... - 12 Drive Design Concept 3 ......................................................................................................... - 13 Drive Design Concept 4 ......................................................................................................... - 15 Drive Design Concept 5 ......................................................................................................... - 15 Drive Design Concept 6 ......................................................................................................... - 16 Drive Design Concept Weighting Factors ............................................................................. - 17 Drive Design Concept Ranking .............................................................................................. - 18 Structure Concept 1 .............................................................................................................. - 18 Structural Concept 2 ............................................................................................................. - 19 Well Base Concepts............................................................................................................... - 20 Outlet Concept 1 ................................................................................................................... - 20 Outlet Concept 2 ................................................................................................................... - 21 Outlet Concept 3 ................................................................................................................... - 22 Rope and Seals ...................................................................................................................... - 22 Final Design Selections ...................................................................................................... - 23 Bike Drive .............................................................................................................................. - 23 Structure ............................................................................................................................... - 24 Outlet .................................................................................................................................... - 24 Rope and Seals ...................................................................................................................... - 25 Guide Box .............................................................................................................................. - 26 Mathematical Model ......................................................................................................... - 27 Water Volume and Weight ................................................................................................... - 27 Drag Force ............................................................................................................................. - 28 Pressure, Friction, and Leakage ............................................................................................ - 29 Final Cost ........................................................................................................................... - 31 Rope Pump ............................................................................................................................ - 31 Bike Mount............................................................................................................................ - 32 Instruction Manual ............................................................................................................ - 33 Miniature Model ............................................................................................................... - 34 Conclusions ....................................................................................................................... - 35 Sources Cited ..................................................................................................................... - 36 -
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Executive Summary In the lush mountainous villages of Guatemala women spend many hours and have to walk many miles every day to get water for her family to cook and drink. Water is a very important resource, that people in first world countries take for granted because it is as easy as turning the faucet handle on. Humans can only survive three to five days without water and getting clean water in third world countries is a difficult problem. Most third world countries get water from standing sources including rivers, lakes, and even puddles which are often full of dirt and other dangerous water borne diseases. In an effort to tap into the potable water just below the surface the MSU Rope pump Team decided to take the widely known designs of one of the simplest and cheapest water pumps, the rope pump, and improve upon them. Our team has enhanced designs for almost every component of the pump. Things such as the frame of the pump which could be made from spare bike parts or just scrap metal. The rope and seals are also an important area of study that we will be spending a majority of our time working on. Traditional rope pumps utilize knots what create a seal within a pipe and bring up water as they are pulled to the surface. A third and final area of study is the drive mechanism of which we are considering wind power, hand power or even many ideas on the use of a bike and its connecting mechanism. After much research, calculations and experimental tests the MSU Rope Pump team were able to find the best combination of improvements to improve output nearly 200% over traditional rope pumps. With the improvements stated in this report the team was able to not only increase the water output to the surface but also eliminate a lot of the danger associated with the construction of the guide box as well as improving the durability of the pump by using proper rope and seal combinations. Finalizing the prototype shows the inclusion of all the best options as well as construction of an optional bike drive and removable handle. Along with the finished prototypes a design and construction guide was completed allowing the new improvements to be downloaded and used worldwide by anyone constructing a new rope pump or updating an old one. A miniature model was also created to show off the idea of a rope pump to communities that might be interested in investing in a rope pump but are finding it hard to visualize how the pump works and its benefits. Our team hopes all of our work this semester will be diffused across many third world countries and if it can improve just one life out there then we can deem all our hard work, sweat and tears a raging success.
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Introduction Imagine that bottled water does not exist, running taps are non-existent, and walking a mile or more to fetch water with a bucket is a daily activity. On top of the difficulties of retrieving water, that source of water is most often than not polluted and undrinkable. But when there is no other source of water, the most essential ingredient to life, there is no choice but to consume the polluted water. High quality H2O is only obtained from chemical treatment, filtering or from a clean ground water well. In a third world country, filtration is often absent, chemical treatment is unheard of, and groundwater wells are not properly built or maintained and also become polluted from run-off. These conditions are those of the bottom 80 percent of the world’s population which live in low standards of living and 48 percent make an average wage of $2.00 USD per day or less. One simple solution for retrieving safe water is by carefully implementing an innovative, human-powered water pump. Our team has accepted the challenge of successfully designing and building an innovative rope pump for use in third world countries. More important than the design itself is the method of communicating how to build, and maintain such a device in the simplest manner possible. With the team’s main focus on the rural areas of Guatemala, we intend to make the rope pump a highly adaptable device for any country. In order to achieve this, the pump must be physically adaptable and also a detailed yet simple and concise handbook will communicate all information needed for construction, maintenance, and adaptable. The handbook will consist of many tables, and pictures that give material selection options and their rankings from most feasible to least desirable making the pump adaptable for any region, any conditions, and eliminating the need for any on the spot design modifications. All of the thinking and designing will be completed for the implementers and documented in the handbook, so all that is needed is a selection of their parameters and materials. With these mountain high goals of simplicity, functionality, and a large target population, the team expects to achieve a large impact in communities worldwide. Results of this design project were intended to improve the quality of life for third world communities by providing easy access to safe drinking water. Even helping one community or even one person within a community by providing clean and safe drinking water by the implementation of our team’s rope pump will be considered success.
Design Specifications Each of the following subsections describes each design specification that must be taken into consideration when developing a rope pump design. Each design specification will then be weighted based on importance in the subsequent section.
Function/Performance Performance of the pump must be able to function in wells up to 20 meters in depth and pump water at a rate at least 5 gallons per minute. With this performance in mind, we wish to -4-
build a pump that can pump at least 5 gallons per minute at an angle (from 0 to 80 degrees, 0 being straight down).
Product Cost In the end the cost of the pump must be no more than $100 USD. The Gross National Income (GNI) Per Capita for Guatemala is $2,740 and for the Lower Middle class the average annual income is $1,619 in US dollars. In the end the pump needs to be below $100 in order to be implemented. Current rope pumps in place range from $35 to $150 depending on model, location of production, and cost of materials and labor.
Delivery Date Delivery date for the working model*, mini-model**, and a training manual to create the pump to be created is no later than April 26, 2013. *=6.096 meter or 20 feet depth, **= 0.6096 meters or 2 feet depth
Quantity A minimum for this project was 1 full* scaled model, 1 mini** model, and a training manual to create the pump to be completed by the delivery date (April 26, 2013). *=6.096 meter or 20 feet depth, **= 0.6096 meters or 2 feet depth
Environmental Issues Product must be created with the aim to create “zero” environmental issues. The parts for the pump are to be used from reusable waste or recycled materials. Safety Operation of the pump must not harm the operator in any way and thus will have a guard protecting the crank mechanism, the rope, the piping from the well, as well as over the well. There will be zero sharp edges to be cut on.
Quality Commonly the rope on the rope pump is most likely to fail. The rope is to be made from a material with a high UV resistance, low water absorption rate (less than 20% water absorbed of its weight in water if full emersion of rope in water for one hour), little to no elasticity, and be able to withstand a water PH level of at least 7.5. The pipe is to be made from a low pressure material that does not break down by UV rays and constant water usage (must last 10 years before breaking).
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Energy Consumption Energy that the pump must consume in order to operate is a critical design specification to meet. The majority of people who use the pump on a daily basis are women and children. The women and weaker children must be able to crank the handle with little difficulty. This means that the force exerted on the handle by the user must be below a specified value. This value is currently unknown but will be determined through experimentation. This experiment will involve a crank that is to be turned by several willing volunteers. These volunteers will be of varying gender, age, strength, and height. This large sample size will allow for the most accurate results. Each volunteer will turn the crank several times each having varying resistance. From this, the maximum force that any given person is able to exert on the crank can be determined. Using these results, that maximum force can be applied to the rope pump design and in turn meet this design specification of 75 watt input, at 5 m head or about 4.5 m³/hour.
Reliability Since the pump is used on a regular basis, reliability is an essential factor. All components must be able to withstand daily utilization without breaking for at least 1 year. This includes the rope, piping, rubber stoppers, crank mechanism, handle, and support structure. The rope must be able to withstand the exerted forces and constant rubbing/friction against the piping without stretching beyond functionality or breaking. The piping must not wear down beyond functionality or crack at any location along the 20m span. The rubber stoppers must keep a strong seal in the piping and not wear from the friction along the piping. The crank mechanism and handle cannot fatigue or fail due to repeated use. The support structure must be strong enough to take the repeated loading and not fatigue or fail. Since the pump will produce a consistent flow rate of 5 gpm throughout its expected lifespan of 20 years, reliability is essential.
Maintenance Bases upon reliability, the pump needs to be able to go untouched/maintenance free for a 1-2 year period. This entails that no components will break or fatigue beyond functionality for at least one year (see reliability). Beyond that, simple lubrication or rope replacement may be needed. After 1 year of use, and every one year thereafter, the pump should be inspected for any wear and determine if components are in need of repair or replacement. Potential crank mechanism repairs/replacement may be needed after 5 years due to climate. This includes the wheel and handle of the crank. All routine maintenance must be able to be completed with the limited tool supply of the locals and require no power machinery. The piping material should be able to last at least 10 years before breaking
Mechanical Loading All moving components of the pump must be able with withstand at least 5 years of repeated loading without major fatigue or failure, averaging about 10,000 cycles. These moving components of the pump include the internals of the crank mechanism. Aside from routine yearly maintenance of lubrication, the mechanism must be able to withstand regular use for 5 years without having to be replaced. This means that material choice has a large impact on the lifespan -6-
of the crank mechanism components. Therefore, this material selection will be researched and chosen carefully.
Size Overall height must be no more than 6 feet tall so that all repair/maintenance can be accessed easily without help from equipment. This will ensure more efficient maintenance and all components are within arms-reach if a situation arises. The crank handle is to be no more than 4 feet from the ground as children must be able to operate the pump without assistance. When disassembled, all components must be small enough to be transported easily (see transportation and packaging).
Weight Total weight of the product must be no more than 50 pounds but may vary due to well depth. Rope pumps must be heavy enough that it does not move around or tip will in use. On the other hand, components must be light enough that transportation by hand is possible. The given 50 pound constraint is for a pump capable of reaching a depth of 20m. Pumps beyond 20m may weigh upward of 50 pounds due to the additional piping and rope needed.
Spatial Constraints There are zero spatial constraints as the pump will be utilized in an open outdoor environment. Aside from any size design specifications (see size).
Aesthetics All metal components are to be coated in a single color of durable/anti-rust paint that is not offensive to the culture of Guatemalan people. Part of aesthetics includes the touch and feel of the product. All edges will be rounded smooth with at least a 0.020” radius. The product will appear clean, smooth and simple. There will be a maximum of 60-65 decibels, the equivalent of a normal conversation, generated from operation, no decibels generated when stationary, and no noise pollution created. The product will appeal to the lower class (bottom 30% of the population in terms of income) and for all age groups.
Transportation and Packaging All components of the pump must be small enough to be transported easily in an available vehicle (approx. 2m x 2m x 2m). The piping must be assembled from short 3-5m sections as transportation of 20m length piping is not possible. All parts will be packaged separately except for any fasteners and pipe fittings which will be bagged together. All other components will be wrapped in 1 layer of bubble wrap and in one cardboard box.
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Personnel People using this pump are men, women, and children of all ages, sizes, strength, and nutrition. The design is to specialize in ease of use for women and children in order to meet the previous criteria. The product will utilize only one person for operation.
Service Life Under normal service conditions the pump must be able to continue to function properly with minimal repair and maintenance for a 5 year period. All components of the pump must be able with withstand at least 1 year of repeated loading without major fatigue or failure. The required repairs during the service life will be rope replacement annually, paint after 3 years and new crank bearings after 3 years.
Noise Radiation Noise pollution must be less than 60 dB as the operator must stand directly next to the pump for operation. To reduce noise all moving joints will be greased with wheel bearing grease, including the crank mechanism bearings.
Operation Instructions One manual is to be provided displaying how the mechanism works, how to assemble and install, how to operate, and tables showing the ideal diameters of pipe/rope for various well depths. The manual will be written so that anyone over the age of 14 in a third world country can understand, install, maintain and operate the rope pump.
Human Factors Rope Pumps must be designed in such a way that human interaction is ergonomically feasible. Design of the pump will incorporate ease of maintenance, operation and installation. The overall installed height of the pump shall not exceed 4 feet. A mechanical advantage of at least 2 will allow anyone to operate the crank mechanism and pump water. Use of the pump will be desirable with noise pollution under 60 dB, mechanical advantage, ergonomic grip, and satisfactory water outputs.
Health Issues Rope pumps will not cause any adverse health effects. In fact with the clean filter option it can actually eliminate 99.9% of water-borne disease through the use of a bio-sand filter. Any pinch points will be covered or addressed to eliminate any accidental injuries. An auto locking feature will also be included to prevent the wheel from reversing in direction while there is water in the pipe causing it to spin rapidly and cause possible injury. All materials will be non-toxic according to US regulations to prevent any toxins from entering the water stream.
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Government Regulations There are zero government regulations regarding types of pumps used. No government regulations currently exist that prevents any of the materials needed to construct the rope pump from being imported if needed. However there is a airport security tax of $3 (US dollars) to leave the country if any of the creators of the rope pump design system were to travel to Guatemala.
Shelf-Life Storage Replacement parts for the rope pump should be available in local shops or junkyards. At these shops the parts would have a limited life span of 10 years before degradation will occur in the polyester rope and rubber stoppers. Metal components (wheel, cover, handles) as long as they are kept out of the weather have a very long life span of nearly 100 years.
Operating Costs There is to be zero operating costs outside of routine maintenance and replacement parts. Human input is used to power the machine unless it is wind driving getting rid of the fuel operating cost. Once the rest of the parts are purchased and assembled on a already dug well there are no further costs to the user besides the use of human power.
Environmental Conditions Access to safe drinking water is a widespread problem throughout most of Guatemala. This leads to many illnesses including intestinal parasites and amoebic dysentery, among others. Industrial and agricultural runoff and intentional pollution is dumped into the rivers and lakes by commercial farms. Products will be made of materials used to withstand UV light that is greater than 3 eV with exposure lasting an average of 16 hours a day year round. Numerous volcanoes in mountains with occasional violent earthquakes also need to be considered in designing a rope pope that can withstand these environmental conditions.
Design Specification Weighting Factors Each design specification was rated based upon weighting factors. Rating was done on a scale of 1 to 5, where 5 is the most important. The results are tabulated in Table 1 below.
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Table 1: Design Specification Weighting Factors
From the Weighting Factor table shown above, it is evident that some design specifications heavily outweigh and hold more importance than others. The design specifications that had a weighting factor of five, therefore being of utmost important, are function/performance, product cost, safety, quality, noise radiation, operating instructions, human factors, health issues, and environmental conditions. As a result, those design specification were be always considered when choosing a final design.
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Conceptual Design Concepts Conceptual ideas below were the result of hours of research and contemplation, which were most certainly subject to change, as well as included additional ideas as the project progressed and experimental results proved an idea worthy of use or not.
Drive Design Concept 1 Drive design concept 1 is through the use of an indoor bicycle trainer device (see Figure 1). Drive design concept 1 is a simple, yet effective, structure that suspends the rear wheel of the bicycle off of the ground allowing the user to pedal in place. There is also a small wheel that the rear wheel of the bicycle rests on. Normally, this is used to create resistance to the user; however, we have no use for the resistance mechanism. Instead, that small wheel will be linked to the top rotating wheel of the rope pump. Therefore, as the bicycle is pedaled it will turn the small wheel, thus rotating the top wheel of the rope pump. Two wheels will be linked using a bicycle chain or of the same rope used in the pump itself. Drive design concept 1 will allow the user to pedal their bicycle in place and simultaneously pump water with minimal effort.
Figure 1: Example of Stationary Bike Trainer There exists several pros and cons of this design concept. The first pro is that the bicycle is easily removable. The user can use their personal bicycle, attach it to their rope pump, and then disconnect and ride away when finished. It will require no modification to the bicycle and is also very easy to use. Simply clamp in the rear axle of the bicycle between the pins, and it is ready to use. So another pro is ease of use. Since the device is of simplistic design and has minimal moving parts, it is less likely to break. This will be beneficial as it creates less maintenance for the user. Another pro is the compact size, allowing for easy transportation to storage or to another rope pump. Design Concept 1 also has several cons. First being that is may be difficult to build with available materials. Since it must support the weight of the rider, the device must be made of - 11 -
high strength steel. It also requires very accurate and reliable bearings and requires the rider to need more stability to use. Since the bicycle is only supported by the rear wheel’s axle, the rider must keep high balance or else they may fall over. Design Concept 1 may prove difficult if children utilize the device. Another con is it may be easily susceptible to theft due to its small and lightweight size. There is the potential for slip between the bike tire and the small wheel on the device. If a large force is needed to turn the pump wheel, slip may occur if not enough force is being applied to the wheel and may cause a loss of efficiency in the pump.
Drive Design Concept 2 Drive Concept 2 also utilizes a stationary bicycle trainer device. Design of this device is much different than the previous. This device utilizes a set of long rollers placed parallel to each other (see Figure 2). The rear wheel of the bicycle sits in the gap between the two rollers (see Figure 3). So the rider can pedal in place and turn the rollers that are in contact with the rear wheel. Transferring the power between the device and the pump is the same as Design Concept 1. One of the rollers will be linked to the top wheel of the rope pump. Therefore, as the bicycle is pedaled it will turn the rollers, thus rotating the top wheel of the rope pump. The roller and pump wheel will be linked using a bicycle chain or of the same rope used in the pump itself and will allow the user to pedal their bicycle in place and simultaneously pump water with minimal effort.
Figure 2: A second example of a Stationary Bike Trainer
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Figure 3: Example of a Roller Bike Trainer One pro of this design concept is that there is no attachment of the bicycle to the device needed. Since the bicycle simply rests on top of the rollers, no modification to the bicycle is necessary. One can use their personal bicycle and ride away when finished pumping water. Similar to the first design concept, the device has minimal moving parts and is very simplistic, creating less maintenance for the user. Another pro is that it could be built easily with available materials and can be made of wood, PVC piping, and basic hardware (see Figure 3), resulting in lower costs. Design Concept 2 is that there will be minimal slip between the roller and the bicycle tire. Unlike design concept 1, 100% of the rider weight will be directly on the rollers. Create a larger force and more friction between the tire and roller will result in minimal slip. Therefore, pump efficiency will be high. Cons of this design concept include high stability of rider, high chance of theft, and a heavier rider is required. Since the bicycle is not supported in any way, the rider must keep perfect balance otherwise they may fall over and may prove difficult for children to accomplish. Theft is a big con as the device is lightweight and small. Therefore, the device must be secured to avoid theft. Lastly, Drive Design Concept 2 will have it so that a light rider will not be as efficient as heavy riders. Since, the amount of friction between the roller and tire depends on the weight of the user; lighter riders will not create as much friction. In turn, when being used by a lighter rider, slip may occur between the rollers and tire, causing a decrease in pump efficiency.
Drive Design Concept 3 Design Concept 3 involves joining the bicycle axle with the top rope pump wheel axle. The rear of the bicycle will be supported off of the ground at the same vertical height as the top wheel of the rope pump and will have the bicycle’s rear axle be lengthened and supported by a frame (see Figure 4). The top pump wheel’s axle will also be lengthened in such a way that the - 13 -
two axles (bike and pump) can be joined together. Axles will be connected using simple hardware that can be easily undone for removal. Since the bicycle wheel and pump wheel now share an axel, pedaling the bike will turn the pump wheel simultaneously pumping water with little effort.
Figure 4: Example of a Mounted Stationary Bike Trainer Pumping Water One major pro of this design concept is that 100% of the power is transferred from the bicycle to the pump, resulting in a high efficiency. Since both wheels share an axle, there is no possibility for any type of slip. There is also no extra stability required of the rider. This is due to the rear axle being completely supported by a frame. The rider has no fear of falling over. Another pro is that any size or age of person can utilize it. Weight is not a factor of efficiency like the previously discussed design concepts and can also be easily constructed from available materials and is of simplistic design. Lastly, since the frame is large and heavy, chances of theft decrease significantly. Major cons of this design concept are that the rear bicycle wheel must be at the same vertical height as the top pump wheel. Therefore, if the rope pump was built with a high wheel, the bicycle will have to be supported very high as well. Another major con is that this design will require some modification to the bicycle. The rear axle must be extended and makes removal of the bicycle much more difficult. The bicycle will still be rideable, but with some slight modifications. Connection of the two axles may also prove fairly difficult and connections must be secure, but also not permanent in order to remove the bicycle after use.
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Drive Design Concept 4 Design Concept 4 uses friction between the rear bicycle wheel and the top rope pump wheel. The rear wheel of the bicycle is supported just off of the ground by the axle, similar to Design Concept 1. It is placed in such a way that the tire butts up against the top wheel of the pump (see Figure 5). Therefore as the bicycle wheel is turned, it will turn the pump wheel by friction between the tire and pump wheel. Pedaling the bicycle will pump water with minimal little.
Figure 5: Example of a Mounted Bike Being Used to Pump Water Pros of this design concept include similar ones to those of the previously discussed design concepts. One being that there is no extra stability needed to utilize the pump. User will have no fear of falling over because the rear wheel is supported by a frame. Any size or age person can operate this device and weight has no effect of pump efficiency. Design Concept 4 is very simplistic and can be easily built from available materials. Since the structure is secured to the ground, theft is less likely to occur. Another pro of this design concept is that no modification is done on the bicycle. Securing the wheel is similar to design concept 1, therefore removal is simple and fast. The bicycle can be ridden normally after the user is done pumping water. One con of the design concept is that the rear wheel of the bicycle must be supported off of the ground. Another major con of the design is that slip may occur between the tire and pump wheel. If there is not enough force between the two wheels, friction will be lowered and slip will occur. Thus, the efficiency of the pump will go down.
Drive Design Concept 5 Design Concept 5 involves some modification to the bicycle. A small third wheel is mounted to the front of the bicycle (see Figure 6) and the wheel is linked to the main sprocket of the bicycle using a chain. The rear wheel of the bicycle must be supported just off the ground so - 15 -
it can rotate freely and is then connected to the top pump wheel by chain or the same rope used in the pump itself. As the bicycle is pedaled, the attached third wheel will rotate, and in turn rotate the top pump wheel. Thus, pedaling the bicycle will pump water with minimal effort.
Figure 6: Mounted Bike Being Used for Mechanical Power A major pro of this design concept is that 100% of the power is transferred to the pump. Since there is no friction necessary, no slip will cause a lowered efficiency and also requires no extra stability to ride. There is no fear of the rider falling over because the rear wheel of the bicycle if fully supported. Another pro is that any age or size person can utilize the device with ease. Another bonus is that the entire concept can be built from available materials and extra bicycle parts. Lastly, since the drive connection device is attached to the bicycle, theft will not be a factor. An obvious con of this design concept is that major modification must be done to the bicycle. A third wheel must be attached and extra chain run to that wheel. Bicycles will not be rideable with the chain attached to the third wheel. In turn, removal of the bicycle from the pump is difficult and requires the removal of a chain. This concept is also more difficult to construct. Bicycle modification must be precise and accurate in order for it to operate properly. Materials are readily available, but skill level of the worker must be high.
Drive Design Concept 6 In the final design concept, a few major modifications were added to the bicycle and are permanently attached. These modifications include the rear tire of the bicycle is removed from the rim, the rear end of the bicycle is mounted to a support frame near the top wheel of the pump, and finally the rear bicycle wheel and top pump wheel is connected via rope, just at the rope runs around the rim of the pump wheel (see Figure 7). There will be tension in the rope and friction will cause the wheels to turn in unison. Pedaling the bicycle will turn the pump wheel, thus pumping water with minimal effort. - 16 -
Figure 7: Another Example of a Mounted Bike Being Used for Power Pros of this design concept includes: extra stability, accept a wide range of users, and is easily constructed. There is no extra stability required to utilize this device because the entire bicycle is supported by a frame. This means that the rider will have no need to fear of falling over. This concept also accepts a wide range of users. Any age, size, or gender person can operate the pump with ease. Weight has no effect on pump efficiency. Lastly, the device is easily constructed from readily available materials. Design of the structure is simplistic and easy to build. This design concept has numerous cons, first being that heavy modification of the bicycle is needed. Due to the modification, bicycle will no longer be rideable and will not be removable like in the previous design concepts. Since the bicycle must be left at the location of the pump, theft is a large factor. Parts and main components may be stolen and it will no longer be usable. The last con is that slip may occur. There must be high tension in the rope running from the rear bicycle wheel to the top pump wheel. Otherwise, slip will occur and pump efficiency will decrease significantly.
Drive Design Concept Weighting Factors When choosing the top design concept, several weighting factors come into play. All of which are a factor in the design concept. They may either be a benefit or a downfall of the design. This brings to question of what factors are most important and why. It is critical to specify what factors have the biggest impact on the possible success or failure of the design. Weighting factors that were examined and rated for our six design concepts are: 1 Bicycle is easily removable from pump 2 Bicycle requires no modifications - 17 -
3 4 5 6 7 8 9 10
Bicycle is still rideable after use Simple to construct Can be made of readily available materials Device is not susceptible to theft Requires no extra or special ability to operate High power transfer efficiency Device is easily maintained Wide range of people can operate the device with ease
Drive Design Concept Ranking All weighting factors were evaluated for each conceptual design concept. If the design concept satisfied the condition, it was given a “1.” If the design concept did not satisfy the condition, it was given a “0.” Each design concept was then totaled. Each of the design concept(s) with the highest score were the top concepts rated by the weighing factors. Results from the tabulated analysis are shown below: Table 2: Drive Design Concept Ranking Concept 1
Concept 2
Concept 3
Concept 4
Concept 5
Concept 6
Easily Removable
1
1
0
1
0
0
No Modifications
1
1
0
1
0
0
Bike Still Rideable
1
1
1
1
1
0
Easy Construction
1
1
0
1
0
1
Available Materials
0
1
1
1
1
1
Low Chance of Theft
0
1
0
0
1
1
Low Ability Required
1
0
1
1
1
1
High Efficiency
0
0
1
0
1
1
Easily Maintained
1
1
1
1
0
1
Usable by All People
0
0
1
1
1
1
6
7
6
8
6
7
TOTAL:
According to the ranking system, conceptual design concept 4 is the best choice based upon the chosen weighting factors. Design concepts 2 and 3 are close behind with one less point than the top choice.
Structure Concept 1 Structure Concept 1 will be a basic A-Frame design with steel plates to reinforce critical joints (see Figure 8). A- Frames are known to be very durable. Size and simplicity of design - 18 -
means fairly easy construction. This design limits the amount of space underneath and can not fit as many well sizes.
Figure 8: Drawing of A-Frame Pump Design
Structural Concept 2 Structure Concept 2 (see Figure 9) will consist of a square base with a A-Frame riser. This design allows for a wider base and is simple to construct. This concept is better for fitting more well types and is less spatially constrained. This design requires slightly more material than concept one as it has 4 additional legs.
Figure 9: Drawing of Trapezoid Based Pump
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Well Base Concepts In theory, the well base will be a simple circular structure and can be made from many different materials (see Figure 10). The base can be made of concrete, wood, mud, sand, mortar, etc. These are used as a barrier seal stop contaminant from entering the water source (see Figure 11).. To ensure that contaminants do not enter the sides of the well a simple stone or brick structure with mortar will be introduced.
Figure 10: Drawing of an Ideal Well for our Design of Pump
Figure 11: Drawing of the Well Cover Needed for our Pump Design
Outlet Concept 1 Water will be collected in a sealed container that will allow users to store their water and have water whenever it is needed (see Figure 12). Holes will be placed on the pipe to allow water to escape into the sealed container and will have a large outlet on the bottom of the container that the water will exit from. Outlet Concept 1 will have a open and close valve to allow water to fill the container with water.
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Figure 12: Drawing of Outlet Capture Apparatus
Outlet Concept 2 Outlet Concept 2 (see Figure 13) will consist of a traditional vertical pipe that will have a funnel around the top to catch the overflow. At the bottom of the funnel there will be a drainage hole to allow the water to flow back down into the well, eliminate the water leakage that is usually present with traditional rope pump designs.
Figure 13: Drawing of Funnel Based Capture Apparatus
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Outlet Concept 3 Outlet Concept 3 (see Figure 14) will be similar to a traditional rope pump design but instead of only one outlet, it will have two. By having two outlets, the second outlet will be above the other outlet and will help to eliminate overflow as well as the possibility of filling two buckets simultaneously.
Figure 14: Drawing of Double Outspout
Rope and Seals Rope material was a major concern as it not only needed to be strong but it also had to have low absorbability as well as low elasticity. There are any choices of material are available that will serve our purpose. Materials like nylon, polyester, polypropylene, hemp, thin steel cable and even fish line. Doing research on these materials allowed us to weed all of these choices down to three to be tested on our prototype and these were polypropylene, polyester and the thin steel cable.
Figure 15: Picture of Initial Rubber Seal Design - 22 -
Figure 15 above shows another major concern we have with this project and that are the seals. Without a solid seal the rope pump would be less effective and thus not create the results we are looking for. Math on leakage paths is being completed to gauge the proper clearances on both sides of the seal within the tube. Finally, the remaining condition that needs to be addressed is the material these seals are made of. Material selection ranges from leather, rubber, wood, just the rope and any other material the indigenous people might find. Once these leakage path calculations give us the proper clearances we should be able to quickly test these materials experimentally to determine the best one.
Final Design Selections As will be seen, the following subsections describe all of the final design selections for each component of the rope pump. All of the selections were based upon experimental results and mathematical calculations which are provided below.
Bike Drive Having the bicycle drive option is designed to be easily detachable and provide a mechanical advantage when pumping at greater depths. This design makes it so no modifications to the bicycle are needed, unlike traditional bike drive systems where the bike is stationary and requires it to be permanently modified. Allowing the bike drive to be the main source of power for the rope pump will allow the user to pump continuously for long periods of time and produces an hours worth of water output more easily than hand driven pumps. In the case where the user does not have a bicycle, a detachable handlebar is in place to allow pumping.
Figure 16: Picture of Optional Bike Mount
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Structure A basic A-Frame structure was chosen to hold our rope pump. An A-Frame can be simply constructed, while maintaining a strong structure for the critical joints in the rope pump. This design uses less material but is more durable than other frame structures. Very few materials are needed for this design and include mild steel tubing, quarter inch thick steel plates and angle iron.
Figure 17: Picture of Finalized A-Frame Support Structure
Outlet More water output and less waste was the main focus with the design of our outlet. We decided to go with the double outlet due to the fact that it allowed greater water output and limited the water wasted overflowing from the riser pipe. We didn't choose the one large outlet pipe due to the fact that it was very difficult if not impossible to find a PVC T-fitting that went from a 1/2” to 1” diameter. Traditional size jump is from 1/2” to 3/4”, thus the larger PVC T’s were used in conjunction with an adapter bushing to attach the riser pipe from the well. This proved to be a successful alternative.
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Figure 18: Picture of Finalized Double Outspout
Rope and Seals Rope comes in many sizes, materials, colors and with many different properties. One of the important things to keep in mind about rope for a pump application is its water absorption and its elasticity. Strength is not an issue because it is extremely rare for a pump rope to handle more than 10 pounds. Elasticity is important because a rope that will stretch when under a working load or when wet will decrease the tension, therefore limiting the necessary friction with the drive wheel. Absorption is critical for two major reasons. First being sanitation and prevention of bacterial growth. A rope that absorbs water may stay wet for extended periods of time, allowing for bacterial growth. Secondly is because of the added pumping weight that should be avoided. Through research and experimentation, we concluded that the best selection for rope is the Polypropylene rope, due to its water “wicking” properties and its strength. When looking for seals, the best selection for seals was found to be rubber. Rubber can be taken from sandals, rubber sheets, rubber sidings, etc. The perfect seal clearance was found to be 40 thousandths below the actual diameter. So for the 1/2” PVC pipe the seals should be punched out to 0.580” diameter. To assist in keeping the rubbers seals’ shape a metal washer should be below and on top of the rubber. This also prevents the rubber seal from sliding past the not and tearing the internal hole or completely off the rope.
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Figure 19: Picture of Finalized Selections of 0.580” Punched Seal on Polypropylene Rope
Guide Box A guide box allows the rope to be directed into the main riser pipe which is what brings the water to the surface. The guide box shown below is the final guide box prototype and is constructed entirely out of PVC pipe. This allows the user to construct their rope pump using fewer materials and resources and at the same time retaining the same lifespan as the rest of the pump parts. Safety and not having to dive down into the well and set the guide box was the main focus with this improved all PVC guide box. To install the guide box, the guide box is mounted to the inlet pipe and is not just set on the ground. Thus, this eliminates the need to dive down and mount the guide box to the bottom of the well. This guide box also provides minimal friction and wear on the rope. This will increase the durability and longevity of the rope pump.
Figure 20: Picture of Finalized All PVC Guide Box
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Mathematical Model A mathematical model for the rope seals was created in order to make critical decisions on the design instead of doing only experimental and guess check work. Full mathematical analysis was done for water weight and volume in the rising pipe, drag force of seals in the pipe, and the pressure, friction, and leakage rates of the seals. Each model will be discussed in full detail in the subsequent three subsections.
Water Volume and Weight Table 3: Recommended Pipe and Rope Based on Well Depth
Table 3 shows the pipe selection on a per meter depth basis. This criterion was set for this selection was to have a range of about 5 to 8 pounds of water in the pipe. These weights seemed very reasonable considering the depth capability of the rope pump, pipe size limitation, and mechanical advantage of the drive mechanism. For example, at a depth of 20 meters (65.617 - 27 -
feet), it is recommended to use 1/2” Schedule 40 PVC pipe with 5/32” diameter polypropylene rope. This combination will yield about 8 pounds of water in the pipe which is quite manageable. This equation used for the calculation was designed strictly for volume and density. Water density used in the mathematical analysis was taken at 60 degrees Fahrenheit, somewhat cooler than room temperature due to the assumption of a cooler underground water temperature, which is approximately 62.37 lb/ft^3. Equation (1) below is the volume formula for a cylinder. When volume is multiplied by the water density the result is weight (equation (2)). V = Πr 2 h
Wt. = Vρ
(1) (2)
Tables like the one above are included in the downloadable instruction manual to help those who are interested in building their own rope pump in choosing the correct pipe diameter. Although this is provided these are guidelines as almost any pipe can be used in any situation as long as the user can handle the increased weight outside of our calculations. To make things clear, the rows were highlighted are the two pipe diameters and depths that were meticulously tested by the team. These models were validated as an accurate weight of water and a reasonable pipe selection for each depth.
Drag Force Table 4: Drag Force Based on Piston Diameter
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As the gap between the piston diameter and the inner diameter of the pipe decreases a linear increase in frictional drag force can be observed. Utilizing these calculations we can promote the optimal diameter compared to the diameter of the pipe. Drag force was calculated to be minimal with respect to the water weight, especially with hydro lubrication when water is being pumped. During experimentation it was found that even a considerably loose seal with .020” diametric clearance did not produce smooth operation of the pump. Therefore the team chose seals at .040” diametric clearance for smooth operation. At this somewhat large clearance the drag friction can be neglected. In order to calculate the drag force the necessary constants needed were: dynamic viscosity of water (.00115 N*s/m^2), velocity (1.404 m/s), inside diameter of the pipe (.01579 meters), piston thickness (.004 meters) and increment of clearance used (.0005 meters). The friction force was calculated by equation (3) which multiplies the piston contact surface area, dynamic viscosity of water, velocity and divides this by the fluid thickness (or clearance between pipe and piston). F = (ΠDLµv)/c
(3)
Pressure, Friction, and Leakage Table 5: Piston Leak Rates Based on Outside Diameter
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After completing calculations based on the clearance of our seals the leakage rate was also found to help with seal clearance decision making. Friction drag compared with the leak rate resulted in two seals that would promote a happy balance between the two. Through experimental results however we were able to further narrow it to the 0.580” diameter seal which worked the smoothest in our prototype tests. In order to calculate the drag force the necessary constants needed were: dynamic viscosity of water (.00115 N*s/m^2), velocity (1.404 m/s), inside diameter of the pipe (.01579 meters), piston thickness (.004 meters), increment of clearance used (.0005 meters) as well as a pressure differential for above and below the seal (unity used since pressure could not be determined). Equation (4) shows how this leak rate was calculated which again is on a per unit of pressure differential basis. QL = (ΔPΠDc 3 )/(12µL)
(4)
Figure 21: Radial Clearance versus Leak Rate Figure 21 shows the graphical representation of the leakage rate versus the radial piston clearance. As it can be noted, the leakage rate is exponential with respect to the radial clearance “c”. Below, in Figure 22, it can be seen how the flow profile in a radial clearance is observed. Based on figure 21 and the unit pressure differential our leakage rate is considerably high but with respect to the overall output of the pump it is relatively low leakage and is allowable. It is the leakage that allows for an ease of pumping by allowing some of the pressurized fluid to flow freely.
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Figure 22: Fluid flow within a radial clearance
Final Cost A final product cost of the rope pump was found based on all necessary materials needed to construct a fully functional rope pump. All material prices were based on purchases made in the United States. All material costs are subject to change if purchased in a different country. Also, several pump components can be salvaged from scrap or old bicycles; therefore, lowering the total cost of materials. A cost analysis was separated into two components: rope pump and bike mount. This was done because some users may not want the more expensive bike drive option and only want to build the pump itself. Both cost breakdowns are discussed in the subsequent two subsections.
Rope Pump For the total cost of the rope pump, all of the necessary materials and the quantity needed are listed in the table below along with their corresponding prices.
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Table 6: Cost Breakdown for Rope Pump
Totaling the prices for each component as listed in the table above, a total cost of $71.75 is found for the rope pump. This total price was within our original design specification of no more that $100. This price point ensures that the majority of people can afford this pump and feel comfortable spending that large sum of money for this product. After finding what can be salvaged from old bikes or junkyards, the cost of the rope pump is decreased to $57.75. This lower price is much more reasonable for people of third world countries to spend.
Bike Mount For the cost of the optional bike mount, all of the necessary materials and the quantity needed are listed in the table below along with their corresponding prices.
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Table 7: Cost Breakdown for Bike Mount
Totaling the prices for each component listed in the table above, a total cost of $64.90 is found for the bike mount. Having the bike drive system is completely optional and is not necessary for the rope pump to function. If the user can afford the bike mount price point, it is a great option to significantly reduce the effort needed to retrieve water from high depth wells. As evident from the table above, the most expensive material for the bike mount is the steel. Any steel can be used for this purpose and is often easily salvaged. Using old and salvaged steel would potentially reduce the cost of the bike mount to zero. If the user were to purchase all materials, a combined rope pump and bike mount price would be $136.65. Again, after subtracting any salvaged materials that combined cost would be well under $70.
Instruction Manual As defined in the design specifications, a rope pump instruction manual was created (see Figure 23). This instruction manual is very easy to follow and understand. Numerous pictures are included to make the process as easy and pain free as possible. In the first sections of the instruction manual explain the theory behind how a rope pump works and also includes a simple diagram showing all basic components. Also given is a table showing the recommended pipe diameter to be use based upon the knowing the depth of the well. Following this section, the portion is broken into three sections: The Rope Pump Assembly, The Guide Box, and The Bike Mount. Each of these sections list all necessary materials, any tools or equipment needed, and step-by-step instructions on how to build it. Pictures are referred to within the instructions to ensure understanding. See separate document for full instruction manual.
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Figure 23: Rope Pump Instruction Manual Cover
Miniature Model A fully functional miniature model was built in order to visually show the components of a rope pump on a small scale (see Figure 24). This miniature model will go hand-in-hand with the instruction manual to help explain how a rope pump works and all of the necessary components. It assists to show the role that each component of the rope pump plays in order to successfully pump water. A visual representation of the layers of the earth has also been added to the outside of the miniature model. This will help to portray the scale as well as to show where certain pump components are located relative to the ground.
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Figure 24: Miniature Model
Conclusions Throughout this semester long project The MSU Rope Pump Team has learned a lot about the deplorable conditions in which people live and get their water. Constant suffering caused by water borne illnesses they can’t see nor understand in the surface water they are forced to drink to survive. We have spent all semester researching, designing and perfecting improvements to the already successful rope pump in order to not only make it more durable but also safer and more beneficial to those that invest in them. Our team has even designed an instructional manual that takes a lot of the guesswork out of the construction by providing our math calculations and our successes. By no means are these absolute but it should make the adaptation to real world users easier. With the instruction manual, miniature model, and website we hope to help at least one person around the world with the diffusion of our hard work.
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Sources Cited http://www.engineeringtoolbox.com/water-specific-volume-weight-d_661.html http://accessengineeringlibrary.com.proxy2.cl.msu.edu/browse/fluid-powerengineering/p200194069970015001?s.num=5&q=leakage+flow&subject=%23DISCIPLINE%23M echanical+engineering#p20019406g200003vpp http://www.engineeringtoolbox.com/water-dynamic-kinematic-viscosity-d_596.html http://www.pipeflow.com/pipe-pressure-drop-calculations/pipe-roughness
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