Supply Gas Check Valves
RE: Infant Incubators & Warmers Report Post
I have never had to clamp lines for the check valve test. You do have to for the relief valve test. You may have a bad check valve.
Official MedWrench Guru
I don't recall clamping off any hoses except for troubleshooting. Main suspects would be the gas and suction switches. Try clamping off the hose to one of them and see if it passes. If it does, replace that switch. Also, check the hose ends where they go into the fittings, sometimes they get loose and leak, cut off the end and plug back in and test again.
I recently had a warmer that had a leak when when testing the brown port. The medical air tank check valve needed to be replaced.