Senior Design 05-06: Team 1
Pump It Up!
The Need - Clean Water:
Worldwide, 1.1 billion people lack access to safe, clean drinking water. That is roughly one-sixth of the world's population. (World Health Organization)
The current manual pumps employ a pump cylinder that is located at the bottom of the well. This cylinder contains many seals that are prone to wear and have to be replaced periodically. The difficulty arises in accessing the cylinder for maintenance which requires extraction of the entire drop pipe.
Our goal is to develop a well pumping system where all of the moving parts are above ground and easily accessible. The pump system will be constructed mainly out of locally available materials in Third World Countries. An airlift pump system requires no moving parts in the well. This will increase the durability of the system.
Click above to see a video of our test pump running.
Our Project Progress:
The original design has been changed - to see the old system concepts click here.
Another project was designing a test well to test our pumping system with. This ended up being a simulated well with pipes off of the second floor of our high-bay. This means that our simulated well is 28 feet deep and the water table can be simulated at just 13 feet below the surface to being completely empty. We have a sight glass on the outside of our simulated well casing so that we can see the water level.
After the water gets pumped out of the simulated well it enters a 55 gallon drum up on a support structure. When this design gets implemented in the feild the structure will only have to be high enough to allow a bucket to fit under the outlet tap. In our situation we had to build it 5 feet tall in order to feed the outlet water back into our simulated well.
The plans for our pump have since changed. Due to the piston ring seal breaking, and a replacement taking weeks to order, we have since revised our plan. A new air compressor has been obtained and all of the drive train is currently in place.
After proving the system on our 28 foot well mock-up, we took the entire system out to field test on a well. The well we used for the test was 140 feet deep with the water level about 102 feet below the surface. This gives a submergance ratio that is slightly less than ideal. This well also has a history of producing sand - so it was a good test of the pump.
This is the pump in operation. The person sits on the seat and pedals the bicycle-like drive train which runs through a step-up gear system. This allows approximately a 13:1 gear ratio allowing speeds that are more optimal for the compressor. The current compressor used is a oil-lubricated, single piston compressor with an inlet air filter. The displacement is about 5.5 cubic inches per stroke with a maximum pressure regulated by the tank's relief valve at 120 psi.
This shows the diffuser assembly that is placed in the bottom of the well. This is the unit that mixes the compressed air with the water and allows both to rise in the drop pipe (rising main) to the surface where the air is vented and the water collected. For this well test we used standard air hose for the air supply line and 1/2 inch water supply pipe for the drop pipe.
After assembling the system we fed the air supply line and the drop pipe together into the well.
During our pumping tests we used an air flow meter to determine the actual flow rate of the supply air.
The result: Water!
Our design proved to be successful at providing water. With some vigourous pedalling the water was pumped up the 100 foot head at a rate of one gallon every minute and thirty seconds. If the input was slowed down to a comfortable pace the output fell to about half a gallon per minute and lower. Overall the design proves to be feasable - especially in cases when the submergance ratio is better and when the seals of a typical down-hole pump cylinder would wear out too rapidly to be practical. This does come at an expense of efficiency - preliminary calculations show that a down-hole pump is over ten times more efficient than the complete air-lift system.
Undoubtably there would be certain situations where the air-lift pump is the best option, however care must be taken to ensure that the inherent disadvantages of the system (largely the low efficiency) are adaquately accounted for.
Things that are currently in progress and should be posted soon are listed below:
This site was last updated on 31 Oct. 2007.