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Please help with homemade pump

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Please help with homemade pump

Unread postAuthor: BigJon » Sat Jan 12, 2008 7:25 pm

Well I have been working on my high pressure pump for quite a while now and I keep running into the same problem. The problem is the homemade check valve at the bottom will not seal (btw I'm using the "floating O-ring" type piston which works just fine). In the past I've used a solid rubber disk sealing against a washer that is epoxied into the threaded adapter and the spring I'm using is pretty strong and was taken out of an air soft pistol. Any help/suggestions is greatly appreciated, thanks.

Edit: I have also tried sealing with some thick lithium based grease. Another thing, I have seen a couple of people use this design so I'm not trying to steal anyone's design.
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Unread postAuthor: jrrdw » Sat Jan 12, 2008 8:06 pm

Is it leaking to the outside of the pump body? Or bleeding back into the compression cylinder??? Has the floating o-ring worked/sealed in this exact pump before? Have you checked the o-ring for cracks, gouges, disformidies?

I don't know the answers to these questions, so i thought i'd ask. :shock:
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Unread postAuthor: BigJon » Sat Jan 12, 2008 8:20 pm

Well it is not the floating o-ring that is the problem believe me I checked that. Like you said air is bleeding back into the compression cylinder.

I'm not sure if this could be the problem but the washer that is epoxied into the fitting at the bottom is a little rusted and maybe it's not getting a perfect seal; what do ya think?

Edit: oh and sorry for the blurry pics I don't know what the heck happened they looked fine when I uploaded them.
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Unread postAuthor: jrrdw » Sun Jan 13, 2008 8:28 am

If it's barely leaking the rust is probly the problem. Can you scrap it off with a screw driver or simular? Or take it out and replace it with a new untouched smooth clean one? I think a new one is your best bet.
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Unread postAuthor: ALIHISGREAT » Sun Jan 13, 2008 8:35 am

if all else fails you coul dalways use an off the shelf check valve?
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Unread postAuthor: BigJon » Sun Jan 13, 2008 1:11 pm

Thanks for the responses guys. I will replace the washer for a new one and see how it goes. But if that doesn't work then I will buy an off the shelf check valve like Alihisgreat suggested. I would like to stay away from that because they can get a little pricey though.
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Unread postAuthor: dongfang » Tue Jan 15, 2008 4:51 am

Hi,

By all means use stainless steel, brass or chrome for the sealing surface.

Regards
Soren
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