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Hello,
I want to make a bulk fill end cap for a QB78 type tube using a male foster with check valve that looks like this:
My question is what holds the plunger into the nipple ? Can it fall out unto the tube innards when the tube is depressurized?
Thanks!:courage:
Yes, it can fall out.... They are usually installed in a blind hole the diameter of the drill required to tap to 1/8" NPT (I use 11/32").... The air passage is smaller than the head of the check valve, so it can't fall into the gun....
Bob
Thanks Bob. I have just read that some fancy check valve nipples have a hollow set screw in the end to hold the plunger captive. What do you think of tapping the inside of the fill nipple to a depth of say 1/8" and running a fine pitch hollow setscrew in to prevent the plunger falling out? Perhaps with a drop of blue loctite on the inner thread to prevent backing out. On second thought, I found this image on the web, which shows how the o-ring sits - and that puts the kaibash on the setscrew idea.Quote:
Originally Posted by rsterne
If the fill adapter is already drilled right through at too large a size.... how about a cross hole in the adapter about 1/8" inside the head of the check valve and a cross pin.... I've seen fittings with a 1/16" brass cross pin for that, B&A I think?....
Bob
This is what I have in mind, for CO2 refills. I may try to find a Male-Female 1/8" NPT nipple, and put a mesh filter in the female end, followed by the check valve. If the M/F nipple is deep enough it should work, I think. Otherwise, an adapter will be machined as Bob described in his first response.