The problem happened a long time ago for me we got called in to look into why our Chlorine cylinder was starving the process with gas. After further investigation to the matter we found that the cylinder pressure would drop off after running for a while. We pulled the gasket(at the cylinder valve connection) and changed the gasket to a Kel-F gasket. The process didn’t experience that problem after that. We were later told that the cylinder connection would cold flow the teflon, the teflon would swell and begin to choke off the flow of gas to the process. Since that day it’s recommended to use Kel-F gaskets for cylinder connections due to swelling experienced with the teflon.