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PCP air gun pumps

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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PCP air gun pumps

Unread postAuthor: auxiliary » Tue Sep 08, 2009 8:21 pm

I have always wanted one of those floor pumps that are capable of filling an HPA tank (with a lot of work), and I always wanted to build a homemade one, but I can't figure out how the 3600+ pressures are reached with a sizable cylinder diameter (.75-1 inches). I think it might have something to do with the pumps having virtually no dead space to allow the pumper to get that last jet of air before the stroke is completed. Do any of you own one of these or know the secret to these things? Here's an example of one:
http://www.pyramydair.com/s/a/AirForce_3_stage_PCP_Hand_Pump_for_AirForce_Rifles_Pumps_up_to_3600_psi/81
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Unread postAuthor: THUNDERLORD » Tue Sep 08, 2009 8:37 pm

...know the secret to these things?...


My guess, low volume (small diameter internally) coupled with long stroke length to get any acceptable output.

No idea what the pump face material is (?)

Mentions "does not heat up" probably just the outside layer does not heat up(?).

BTW, looks like a "PCP" or similar avatar...pretty groovy. :P
8)
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Unread postAuthor: auxiliary » Tue Sep 08, 2009 8:47 pm

I think that there is something more to it than a small diameter. For instance, if the cylinder was only 0.5 inches in inside diameter (I think that the pumps are wider), the force needed to compress the pump at let's say 3000psi would be 589 pounds. I hope nobody here weighs that much.

That's a funny coincidence that I thought of PCP pumps after a got a new avatar. :lol:
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Unread postAuthor: theBOOM » Tue Sep 08, 2009 9:01 pm

How would they work then? would it even be possible to actually get to 3600 psi for a REGULAR human?
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Unread postAuthor: jackssmirkingrevenge » Tue Sep 08, 2009 9:49 pm

They're usually not simple ordinary pumps but of multi-stage construction (and I believe there is something similar on this forum), have a look at this patent for the popular FX design.
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Unread postAuthor: THUNDERLORD » Tue Sep 08, 2009 10:51 pm

JSR wrote:...have a look at this patent for the popular FX design.


Finally, I was starting to become "an idiot in suspense". :roll:
(although it looks like the action starts with a smaller diameter).

auxiliary wrote:...after a got a new avatar...


Your Sig. could read:
"If avatar appears to be moving, you may have an N2O leak". :P 8)
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Unread postAuthor: D_Hall » Tue Sep 08, 2009 10:59 pm

What makes you so sure that they're 0.5" in diameter? That may be small to you, but in the world of manual high pressure pumps that's pretty damned big.

Try 0.25" on for size. Suddenly to get to that 3000 psi you only need 150 pounds. Very doable.
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Unread postAuthor: turner » Tue Sep 08, 2009 11:01 pm

http://www.pyramydair.com/site/articles/hand-pump/
idk about the seals but your supposed to pump for like 15 minutes then let it cool down
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Unread postAuthor: absinthe » Tue Sep 08, 2009 11:29 pm

these are a 3 stage pump.. thats how the pressure is achievable with any volume
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Unread postAuthor: jackssmirkingrevenge » Tue Sep 08, 2009 11:47 pm

A homebuilt 2 stage pump by spudamine, have a look here ;)
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