PRO02: Level Control
The objective of this experiment is to become familiar with process control hardware (valves, transmit- ters, and controllers) and to study PI control of level, both experimentally and theoretically. The flow of water into a tank from the pumping station is set by manual valves. Water is pumped from the tank using a centrifugal pump. Two automatic pneumatic control valves in the piping after the pump are arranged in parallel so that either one can be used to regulate the flow back to the pumping station. Tank level is measured by a pneumatic differential-pressure transmitter whose output signal (the process variable, PV) varies from 3 to 15 psig. The level controller output signal (PV) sets the position of the control valves. Another pneumatic differential-pressure transmitter measures the pressure drop over an orifice plate, so it serves as a flow transmitter. One of the control valves has “valve positioner”, while the other does not.