Good call about the volume, Sean, I missed that....

It turns out that in the final version, there is only a "pinhole" feeding the space under the gauge.... Therefore, on further consideration.... if you have a very small hole feeding the space under the gauge, and that space is small, the "explosion" would be limited to maybe 1 FPE of energy released, depending on the volume and the pressure.... As shown, there is a potential for injury in the result of a failure.... That may not be the case if you keep the volume under the gauge, and the hole pressurizing it, small enough....

I still wouldn't do it, but in terms of safety, it MAY be OK because of the flow limiting "pinhole"....

Bob