Building a pump from scratch, engineering competition

[Mike.]

***Building a pump from scratch, engineering competition***

Hello everyone.

I have been entered into a competition.

The spec is to build a pump that can pump 30 litres of water a minuet for 30 minuet to a height of 4 meters.

The pump has to be built over 3 days (18hours) but i have until January to plan the build (and hopefully practice it)

I am just asking for simple ideas of what to make, i am a mechanical engineering apprentice, i have skills in turning milling CNC CAD etc, but all the pumps i have worked on are all cast.

So mainly my question is, What do you think the best type of pump would be to make a centrifugal one or a PD one(keeping in mind that the simpler/cheaper the better)
It doesn't have to be bullet proof as it only has to run for 30min

Any ideas or thoughts would be great.

All the best

Mike

 

[Topher925]

I would go with either a centrifugal or a mixed flow design since it will be the simplest. Euler's equations will give you a +/- 25% estimate of the pumps performance. What materials do you have to work with? Do you have full access to CNC lathes/mills? Is there a budget? What criteria will decide who wins the competition?

Most pumps are cast instead of machined because its cheaper, not because it performs better.

 

[FredGarvin]

The simplest is going to be a PD pump similar to what has been used for water wells for centuries. A centrif will require some pretty high end machining as well as design even if it will be extremely inefficient. A cylinder is a pretty easy thing to design and make. The worst thing to think about would be the sealing. A two way hand pump would give you the flow you need and the head is only 4 ft which is nothing.

However, you don't mention anything as far as other rules or constraints for the competition. Do you get more points for more flow? If that's the case maybe a centrif is the way to go. You would need to think of getting a prime mover though.

http://www.bisonpumps.com/

 

[Mike.]

IT has to pump 30liters of water per min for 30 min.

So after 30 min they want 900 liters in a tank (4 meters high)

Cost isn't a problem but cheaper is better.
Weight is a problem having to be less than 15kg.

Our idea firstly was a centrifugal pump, but it needs to be self priming.

So we thought of a PD pump, kinda like a single cylinder engine just pumping water not fuel.

We just need to get a motor powerful enough/ light enough to power the pump.

We though a good point to start from would be to 5 liters ever 10 sec.

The idea would be to either have 1, 5 litre piston or 3, 1.7 litre pistons.

Its just a case of working out how much force we would need to push/pull the piston within the cylinder.

I know that presser is force over area, and i know the area but don't know the pressure.

Any ideas?

We also don't know how for the pump will have to self prime. I.e the inlet vessel might be 1 ft away or it could be 30

 

[Mike.]

IT has to pump 30liters of water per min for 30 min.

So after 30 min they want 900 liters in a tank (4 meters high)

Cost isn't a problem but cheaper is better.
Weight is a problem having to be less than 15kg.

Our idea firstly was a centrifugal pump, but it needs to be self priming.

So we thought of a PD pump, kinda like a single cylinder engine just pumping water not fuel.

We just need to get a motor powerful enough/ light enough to power the pump.

We though a good point to start from would be to 5 liters ever 10 sec.

The idea would be to either have 1, 5 litre piston or 3, 1.7 litre pistons.

Its just a case of working out how much force we would need to push/pull the piston within the cylinder.

I know that presser is force over area, and i know the area but don't know the pressure.

Any ideas?

We also don't know how for the pump will have to self prime. I.e the inlet vessel might be 1 ft away or it could be 30

 

[Topher925]

Again, why kind of equipment and tools do you have available? Do you have a fully equipped machine shop or a shack behind your house?

 

[Mike.]

Fully equipped workshop, all brand new machines.
And i can take any tools i like to the compertition.

 

[Topher925]

Since you have a full fledged machine shop, you need a self priming pump, and weight is going to be a significant issue I would go with a gear type or maybe gerotor type pump. Both require tight tolerances and surface machining but since you have the equipment it shouldn't be to much of an issue.