Pressure elements should be designed to minimize corrosion. Unless the process fluid requires better corrosion resistance, pressure elements should be 316 stainless steel (316 SS).…

Pressure instruments should withstand the maximum operating pressures encountered. Under unusual conditions, such as thermal expansion, the instrument may exceed its range. Most instruments can…

Pressure instruments with Bourdon tube, bellows, or diaphragm sensing elements may use either force-balance or motion-balance mechanisms to convert the element movement into an output…

Pressure instruments should read in the following units: • Above atmospheric: Pounds per square inch gage (psig), inches of water (inches H2O), or inches of…

The ultimate sensitivity method ( Figure 300-24) is also a closed loop test. Adjust the integral time and/or the derivative time to their minimum values.…

The quarter decay method is a closed loop controller tuning method. This means that the controller remains in automatic while tuning adjustments are made. The…

Feed-forward control measures a disturbance before it can affect the controlled variable, and changes the manipulated variable to compensate for the disturbance. Of course, for…

Cascade control should also be considered when the primary control variable is slow to react to disturbances. Like any feedback control loop, a cascade control…

With derivative action (also called rate action), the controller output is proportional to the rate of change of the error. This means the faster the…

Integral time should be proportional to the time it takes for the process to respond to control action. When the process responds quickly, the integral…