high pressure pump

[inonickname]

very nice pump man.

would it work to attach the outlet of a 100psi compressor to the second stage inlet instead of having a first stage?

also i dont understand floating orings so if some one could help me with that it would be great!

Floating o-rings are simple. On the downstroke they are forced against the piston, sealing the chamber and compressing the air. On the upstroke the o ring has a small amount of movement and travels down, allowing air from around the piston into the cylinder through a gap.

By doing that you run slight risk of pneumatic ramming but it would be workable.

[jeepkahn]

Not critiqueing at all, just did some numbers on making a pump like yours but with a larger first stage, for referance of those who may be interested in making one similar...

sorry about the imperial units, not sure of standard metric copper sizes...

I'm guessing yours in imp would be 3/4" 1st stage and 1/2" second stage(inside diameters) for a first stage compression ratio of 3.25:1 (assuming 20" stroke) and a volume of 12.755 cubic inches pumped per revolution...

now, if you upped it to a 1" first stage, it would raise the first stage comp ratio to 5:1 and a pumped volume of 19.625 cubic inches per revolution....

and if you wanted get really hi volume you could go with a 2" first stage, the first stage comp ratio would jump to 17:1 and a pumped volume of 66.725 cubic inches per revolution...

but if I'm doing my math corrctly, the actually effort required on the first stage would be 21.45lbs at the compressed end of the stroke. 58.875 lbs with the 1" first stage, and 800.7lbs with the 2" first stage....

If someone can correct my math (if it's wrong) please do so...

[Ragnarok]

Nothing strictly wrong, but just so you know the sizes, 22mm copper has a 20.3mm ID (~0.8"), 15mm copper has a 13.5mm ID (~0.53).

Also, I suspect that 800 lb loads for the 2" pump are possibly in excess of what most of us are capable of.

1" however might be achievable, if starting to get on the "lot of work" side.

[jeepkahn]

the 2" inche #'s were more for a referance than what's feasible... but 66.75 lifting pounds over a coupla inches for the sake of 40% fewer strokes might be beneficial....And it may work out to evenless than that considering the chamber pressure would rise quicker....

[spudamine]

I think 1" would probably be doable, mine is really quite easy on the upstroke, although you have to bear in mind that the force comes at the point where you're arms have the least mechanical advantage, at least for people with a normal human physiology
also remember to factor in the volume of the piston rod inside the first stage

Yep, I will now be building a launcher hopefully worthy of this pump, it's going to be around 15mm calibre firing a saboted dart, with a 6 round magazine