Inline Regulator and Pressure Tester

About a year ago I made an adjustable inline regulator for tethering airguns to a large tank, but it was less than successful.... The pressure range was limited and drifted and it was slow to come back to pressure.... I have comtemplated getting an adjustable regulator, but they are over $300 and I questioned whether I really need it adjustable anyway.... The primary use would be for testing and target shooting and filling from a 4500 psi tank, and most of my guns I would do that at 200 bar (2900 psi) or 3000 psi.... I had a brand new, 4500 psi Ninja Paintball regulator sitting here, so I decided to make it into an inline reg....

There really isn't a lot you have to do, basically just block off the threaded end that screws into the neck of the tank.... Unfortunately, there are 2 vent holes right up against the O-ring, so you can't just drill the threaded end and insert a pipe plug.... I decided to machine off the threads just to the vent holes and drill and tap the base 1/8" NPT, but there is barely enough length for the tap, in fact I had to use a tap which was more like a bottoming tap to get the threads deep enough without drilling through into the holes where the gauge, inlet, and HP burst disc are.... I managed it, but if I had it to do over again, I think I'd just take a piece of 1" diam. aluminum , drill and tap it 5/8"-18 NF, cut in an O-ring shoulder, and thread the reg. into that to seal the bottom end off.... The other modification I did was to remove the bonnet, pull out the pin valve assembly, and drill the bonnet out to 11/32" and tap it 1/8" NPT and install a female Foster for the outlet....Oh, I also removed the check valve in the male Foster inlet, although not really necessary.... Anyway, I ended up with this....

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You need a gauge to adjust the regulator setpoint, and a bleed valve on the outlet side between the reg. and the gun, and I already had the one above, with a male Foster on the inlet and a female on a short hose on the outlet.... There is a bleed valve in the aluminum block, behind the gauge.... I made up a plug on a male Foster to block off the outlet, and set about adjusting the regulator to 2900 psi....

This reg. had a coil spring inside, as it was only set for 850 psi.... I knew that the normal 0.032" Bellevilles wouldn't go high enough, they would compress flat before developing enough force for 2900 psi, so I had two choices.... I could double them up to increase the force, but that cuts the travel in half and makes them fussy to shim.... However, I had some 0.047" thick Bellevilles, and I knew that 8 of them would fit because that is what Ninja use in their regs. for 2000 psi and over, at least in the ones I have seen.... I tried a stack of 8, and had to use a 0.020" shim just to keep them from rattling around.... With 0.040" of shimming, the pressure was 2400 psi, so I needed more shims.... I measured the height of a 0.047" Belleville, and it was 0.059", and I knew that adding one more would reduce the spring rate so I figured it was worth a try.... I put a 0.002" shim against the inside of the aluminum body just to make sure the sharp edge of the Belleville didn't dig in, and found out it had 0.032" of preload so I knew the stack wouldn't go flat and bind up.... To my surprise and delight, I got exactly 2900 psi.... Here is the stack of 0.047" Bellevilles I used....

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The flat shim is against the body of the regulator, and the large part of the piston that the Bellevilles push against is at the other end, bearing on the convex side of the last Belleville.... Individual regs may vary, and you could be over or under 2900 psi, but it worked for me.... If you need less pressure, you will have to use just 8 Bellevilles (leave off the one on the right, on the piston) and increase the stack of shims.... If you want more pressure, just add more flat shims, but be advised it doesn't take much with the 0.047" Bellevilles, roughly 40 psi per 0.001" of shimming.... so a 0.005" shim is about 200 psi....

As with any time you are working with HPA, if you don't know what you are doing.... DON'T !!!

Bob