Model 422 & Model 422CC Instruction Manual
D01187869
Revision A, December 2015
38
the need to evacuate chamber pressure becomes necessary. If this switch is
depressed, the instrument will immediately release all pressure within the pressure
vessel. Another use for the manual pressure release switch is to evacuate any
residual pressure left over from a test. When the instrument has finished the “drain
cylinder” procedure, there is sometimes residual air pressure from the air inlet
pushing the oil back into the reservoir. Usually, this residual pressure is vented
when carefully and slowly loosening the thermocouple nut on top of the pressure
vessel plug.