SpudFiles

Hi everybody.
My second project is pretty much finished, it's a pcp with hammer valve.
since I'm using a co2 tank i plan to reach 70-80 bar (around 1000 psi) and to do that i built a stirrup pump.
i'm having some troubles with the pump though: i reached 38 bar pretty easily with a small chamber, just to test it before to charge the tank.. but since then i can't pass 20 bar, don't understand why. it seems that the piston doesn't work well anymore, it's not fluid and it takes far longer to pump even to 5 bar. i'm using a check valve for high pressures,the chamber is not leaking, so i reckon the problem is the piston. i'm not using the piston that i've found often on spudfiles (like gipetto's easy stirrup pump), instead the o ring seals in both directions and i drilled a hole at the top of the plastic pipe, so that it refills the pump every stroke. the diameter is only 9mm, i wonder if it's possible to make a decent piston of that size.. in any case, that's the only possible way to reach 70 bar, unless i build a four stage pump :albino:

Why not use a floating o ring piston? 1000 psi is a lot of air in your chamber, it will take quite a lot of pumping. There are other options as well, such as co2, or fridge compressors that can reach pressures close to your requirements.

it's hard to make a piston of that size and i have to use the pump, nothing else

Nifty set-up! Have you calculated your dead volume, this could be the issue with higher pressure.

Yes sure, i tried to reduce the dead volume both before and after the check valve. I've found out that probably the o ring of the piston is of the wrong diameter: it should be slightly bigger than the cylinder and not strech when put in its seat. That's the whole thing i reckon.. Please tell me if i'm wrong

Why don't you make the pump head like Gipetto made his, it's an easy design to replicate.

50 bar reached with a floating o ring piston and a lot of pumping..yeah