Or instead of a pop-off, use a regulator between the gas source and the BB chamber. If you don't want the chamber above 100 PSI (for PVC) then set the reg to that pressure. The reg should be very close, if not directly mounted on, the chamber. This would require a reg with pretty high flow.jackssmirkingrevenge wrote:Given the way BBMGs work, you could probably use 275 psi directly in an appropriately rated PVC tee, just maybe add a pop-off valve for safety.
As Jack suggests, most BBMGs are flow restricted. The gas source pressure is much higher than the chamber/barrel pressure since you can't flow gas fast enough to get the chamber/barrel up to the source pressure. A 125 PSIG gas source, through 25' of 3/8" ID hose, then a blowgun valve, then through a several in^3 chamber, then a couple feet of 0.18" ID pipe gives chamber/barrel pressures of only about 20 PSIG. And that only when a BB is actually in the barrel, when the barrel is empty the chamber pressure is even lower.