I want to know why temperature sensors in the process pipe line doesn't need to have isolation valves?

Question

I want to know why temperature sensors in the process pipe line doesn't need to have isolation valves?

Answer 1

Put the probes in thermowells, then they can be removed (like for repair or calibration) without shutting down the system. The thermowell is at the same temp as the process fluid, so the temp probe does NOT need to be in contact with the fluid (this also saves $ on probes if you're dealing with a harsh process envirnment!). Unfortunately this strategy doesnt work for things like pH or conductivity probes as these need to be in contact with the fluid.