Adding a pressure gauge to pcp tube

[Rollin333z]

Hello all,
Can I place a gauge block and pressure gauge anywhere on a pcp tube if I drill the hole the same diameter as the gauge thread? I fill to 3000psi, was wondering if there’s too much force acting on gauge thread to hold the gauge block in place. On most crosman models, I see there’s a spacer between the gauge block and the power valve to hold the gauge block in place or the gauge block is right against the power valve. I’m using a custom stock and Cothran pcp tube so I need to place the pressure gauge near the middle.
Thanks for all the input. Btw, I am getting a longer pcp tube, the 2250 length is too short

[Rob M]

drill away.. it doesnt make a diffefrence as far as hoop stress .. Longitudinal stress is there in full force, but the .390 ish hole isnt enough to compromise the tube .

[Rollin333z]

Awesome, thanks for your help 😇

[dmeguy]

You will need a gauge block. There is not enough material in the tube itself. A P-rod gauge port will work perfect for the Cothran tube.

[Rick67]

You will need a gauge block. There is not enough material in the tube itself. A P-rod gauge port will work perfect for the Cothran tube.

PROD or Disco gauge block, but you have to drill the tube, of course.

Mr. Cothran sells his tubes w/o gauge holes, but perhaps he can be persuaded to do so (I have 3 of his 22xx stainless tubes).

Anyway, the Disco gauge block has a smaller air hole though and uses a different gauge and gauge thread (1/8 BSPP non-tapered and seals with a size A009 O-ring) unlike the PROD’s tapered 1/8 NPT, which utilizes a teflon tape for sealing.

The air hole does not matter if you are in the quest for low or medium power, btw.

There are also better choices of gauges (e.g., 1/8 BSPP Wika gauge from Trenier Outdoors) for the Disco gauge port.


Footnote(s):

Two A016 O-rings for the Disco G block.

Two A113 O-rings for the PROD G block.

[Ribbonstone]

Could always order what we know already works….both parts, the block and the gauge connection.  If it works on one 3K PCP, should work on any other 3K PCP..

They do get some backward stress.  The block is a restriction,  when fired, the pressure will be lower at the valve side and higher at the muzzle side…..air will even out, the flow moving towards the low(valve) side.

Should be that much slack in the tube hole….on the factory ones, that slack is always been taken up towards the rear.

If a DIY type addition, could side-mount the gauge (as they do on the Challenger)  which has always been easier to read than flipping the rifle over.

[Rollin333z]

Thanks for the info guys, much appreciated