Would pumping down on a gas cylinder regulator cause the needle of the valve to break since it’s trying to go below zero? Would this also cause a problem with the regulator itself? I’ve included the actual picture of the regulator.

Thanks for your time!

Gas cylinder regulator


1 Answer 1


I doubt there would be a problem. That type of gauge has a bourdon tube inside that has a curved flattened tube. The tube goes from flat to round as the pressure increases which straightens out the curve and moves the needle. If you subject it to negative pressure, the tube will flatten out more and pull the needle towards the peg. The lowest vacuum you can get is about -15 PSIG. On the high pressure side, the needle goes up to something like 4000 PSI. 15 PSI is 0.375% of 4000 PSI. I am not sure it would even notice if you pushed the needle the wrong way by 15 PSI. The low pressure side is a bit more of a concern. The peg will keep the needle from going the wrong way so the internal mechanism won't run off the end and that much pressure certainly won't bend anything. You will be fine.

If you don't wish to trust your equipment to some dude on the internet, I suggest you call up the gauge manufacturer, which in this case is Matheson and ask to talk to tech support. They want their products to be used correctly and most vendors will be happy to answers questions. I have never called Matheson but I have asked manufacturers about equipment that has been in service for years and years (and sometimes out of service for years and years) and almost every time, they have gone out of their way to be helpful.


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