A substrate processing apparatus for processing wafers has a first processing chamber capable of containing the wafers and a second processing chamber capable of containing the wafers. The IR thermometer also includes one or more secondary sensors configured to provide an IR thermometer positioning data. The function produces an estimate of the expected input power consumed by the compressor unit, and this expected input power is compared with an actual input power measured from the compressor unit. A mount for mounting a machining tool for machining the circularly arcuate component or a circular component may also be provided.