Making A Pump

[crokett]

As an offshoot of some plumbing questions my 5 yr old asked me, I am designing a hand pump - think the old-school ones with the long lever handle. The mechanics for the lever handle are simple enough, my question was on the pump cylinder itself. Right now I am thinking about 3 or 4" PVC with a T on the bottom. 1 side of the T would be intake, other side would be exhaust. There would be check valves on the intake and exhaust. I would cap the bottom of the T. I would probably arrange the intake to be gravity fed. The only thing I have a question on is making the piston in the pump. Wood will eventually rot. I was thinking along the lines of cutting down a fitting that matches the ID of the pump cylinder and adding a rubber stop to it or something.

Any ideas?

[atgcpaul]

One consideration is to not make your stopper too thin. This will prevent it
from rocking in the pipe and cause water to bypass it.

You could make 3 discs out of ipe decking which I'm told can be submerged for years without showing wear. 2 discs to match the ID of the pipe and a
3rd disc sandwiched in between but at a smaller diameter. Around that middle
disc, you snap on your O-ring.

[crokett]

Paul, thanks. I was actually thinking about the composite decking, but ipe would work as well. Another idea I had was it occurs to me there are rubber stoppers designed to fit into drains and you tighten a bolt down to expand the rubber up against the walls of the pipe. As I recall, they are backed by a metal washer. I might try that, just not tighten the bolt all the way.

Now next question is, would PVC withstand the pressure needed to lift, say the water in a 1.5" PVC pipe 6' or so? I am not sure how to figure that out.

[FL Buckeye]

If you have any scrap flat plastic material, maybe from making a jig or guide, you could use it for the 3 discs as Paul suggested. Or just use two discs and sandwich a piece of rubber, like bicycle inner tube between the discs for the seal.

[Shep]

What about the rubber from a hockey puck? I'm sure you could mill it down to size.

[cabinetman]

These should help you out.
http://www.ehow.com/how_2292117_make-hand-pump.html
http://en.howtopedia.org/wiki/How_to_Make_a_Hand_Pump
.

[crokett]

Cabman, that first link does help. Thanks.

[Tom Slick]

Maybe you could use HDPE from a cutting board.

[crokett]

I am thinking lexan or UHMW for the discs, I have some of both. For the rubber seals I have way more ice dam then I will ever use. I think I will stick two pieces together and cut the circles out of that. I am also wondering if the T idea with check valves would scale any better for a big pump.

[LCHIEN]

Now next question is, would PVC withstand the pressure needed to lift, say the water in a 1.5" PVC pipe 6' or so? I am not sure how to figure that out.

its easy. You need to raise water 6' then you need 6 feet of head or 6 feet of water pressure (feet of pressure is a measure of pressure, JUST DIFFERENT UNITS THAN psi). regardless of the diameter, just the column height.

The conversion for feet of water to PSI is approx 1/2 PSI per foot. So you'll need a minimum iof 3 psi to raise water 6 feet. Just about any PVC pipe of any schedule will withstand 3 PSI.

[crokett]

Thanks Loring. Now I need to get some parts and do some experimenting. I like the T idea better. I will let you know how it goes.