I have a Class 1 aluminum vacuum brazing furnace (per AMS2750 G) that has seven zone thermocouples. When performing a system accuracy test (SAT), must I verify all seven zone temperatures are within ±2° F of the SAT thermocouples installed for the test?
According to paragraph 188.8.131.52. of AMS2750G:
“The SAT shall be performed on all control and recording systems required by the applicable instrumentation type, as well as any additional recording systems used for parts and raw material acceptance in each control zone of each piece of thermal processing equipment used for production heat treatments.”
That means you should perform SAT on all control temperatures as well as any other temperature measurement system which are required by instrumentation type. For example Load thermocouples for instrumentation type A and B.
SAT is not required for overtemp systems (if overtemp protection is the only function of that system).
Each of those ‘systems’ (Thermocouple, TC wires, feedthroughs, and measuring/recording instrument) should be within SAT tolerance (which is 2F for class 1 equipment) to their SAT sensor.