Infrared Open Path Gas Detectors Working Principle
An alternative method of measuring gas concentration is based on absorption of infrared (IR) radiation at certain wavelengths as it passes through a volume of gas. Devices using this technology have a…
Integral Controller Principle
Reset of Integral Action Most of the processes we will be controlling will have a clearly defined setpoint. If we wish to restore the process to the setpoint after a disturbance then…
Derivative Controller Principle
RATE OR DERIVATIVE ACTION Consider a control system subjected to a disturbance, which causes the error to increase in a ramped manner. Proportional control would respond to this ramped error with a…
Thermocouple and its Principle
A thermocouple consists of two pieces of dissimilar metals with their ends joined together (by twisting, soldering or welding). When heat is applied to the junction, a voltage, in the range of…
RTD Wheatstone Bridge Circuits
Every type of metal has a unique composition and has a different resistance to the flow of electrical current. This is termed the resistively constant for that metal. For most metals the…
Digital Control Valve Working Principle
Diaphragm Digital Control Valve is an electrically actuated, hydraulically operated multi-function control valve. It can be used for local as well as remote controlled batching operations with electronic batch controller.…
Effect of Temperature & Pressure on Level Measurement
Level measurement systems that use differential pressure ΔP as the sensing method, are by their very nature affected by temperature and pressure. Recall that the measured height H of a column…
Boiler Drum Level Control Systems
Drum Level Control Systems are used extensively throughout the process industries and the Utilities to control the level of boiling water contained in boiler drums on process plant and help…
Single Element Drum Level Control System
The Below Figure depicts the control scheme for single-element drum level control. In this configuration, only the water level in the drum is being measured (hence the term " single…
Two Element Drum Level Control System
A two-element drum level control system is capable of providing close adherence of drum level to its set-point under steady-state conditions as well as being capable of providing the required…
