Hi all, I need to knock up a small , say 10 mm piston dia, hand operated force pump to do a hydraulic (water) test to around 15 psi ( but want it capable to at least 300 + psi ) Cyl / piston is the easy bit, but am looking for ideas for small non-return valves. My current lash-up uses top-hat poppets about 4 mm dia with o rings on mating to flat brass faces ( ends of air fittings ) with springs, work ok exept that the inlet one is a bit unreliable and sometimes makes it difficult to prime the pump.This current pump is a re-hash of a motor driven one I made for another job and worked ok then to 350 psi, but the slow & stop start hand operated action seems to be the problem. So any Ideas out there for small NR valves, I am trying to avoid lapping at this scale and want to make in S/S. Cheers, Mark. G.
force pump
Jan 27, 2007
4 Replies
In message , Mark G writes
If the valves are permanently in an upright position a simple stainless-steel or polypropylene ball in a bronze housing probably takes a lot of beating. Few things could be simpler to make provided you have an old fashioned D-bit for machining the valve seat. There are optimum proportions for the relative sizes of ball, orifice, ball housing and lift. I may be able to find references somewhere. But failing that, the clack valves and/or hand pump in the published drawings for almost any
5" or 7 1/4" model steam loco are likely to be in the sizes you are looking for and thus a possible starting point.Thanks Mike, As I am now searching for S/S balls & springs it might interest group that the source so far is household cleaner spray bottles, dont know why I never thought of this before, but each one of the two so far has yielded a 1/8" S/S or plastic ball and a S/S spring, now looking to see if I can find a larger dia ball, but can work with 1/8 if I have to. Mark G.
"Mike H"
In message , Mark G writes
So long as the ball lift is constrained and the valve barrel is upright there is no need for a spring.
had you thought of the one-way valve used in a car washer bottle situation I also have a box of pneumatic fittings (small) I sure there are some in there if you let me know the id your looking for Ill look
Andrew
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