Offcourse temp control valve controls temp, and pressure control valve controls pressure....and so on. I am wondering, what are the mechnical differences in the valves body and how are they operated in terms of process control.
In principle all valves are flow control valves. What changes is the variable they are controlling. A temperature control valve controls a flow to heat or cool another fluid. A pressure control valve, controls a flow to maintain the pressure in a vessel. As pointed earlier, valves can be self contained, i.e., the sensor is part of the control mechanism, usually a diaprhagm which moves the valve stem. and a spring to adjust a set point. Or, they can be pneumatic or electronic, in which case there is an external power source, transducer and controller to adjust set point, gain, reset and rate. This gives additional flexibility, if needed, depending on the process to be controlled. .
