Recognizing an Over-Tuned PID Controller by Phase Shift
When performing heuristic tuning of a PID controller, it is important to be able to identify a condition where one or more of the “actions” (P, I, or D) is…
Recognizing a Porpoising PID Controller
An interesting case of over-tuning is when the process variable “porpoises” (Note 1 ) on its way to setpoint following a step-change in setpoint. Note 1 : The term “porpoise” comes…
Particle Image Velocimetry (PIV) Principle
Particle image velocimetry (PIV) is an optical method of flow visualization used to obtain instantaneous velocity measurements and related properties in fluids.
Ziegler-Nichols Open-Loop Method
In contrast to the first tuning technique presented by Ziegler and Nichols in their landmark 1942 paper where the process was made to oscillate using proportional-only automatic control and the…
Ziegler-Nichols Closed-Loop Method (Ultimate Gain)
Closed-loop refers to the operation of a control system with the controlling device in “automatic” mode, where the flow of the information from sensing element to transmitter to controller to…
Heuristic PID Tuning Method
Heuristic PID Tuning Method In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller settings are obtained through data collection and analysis, a heuristic…
Quantitative PID tuning procedures
A quantitative PID tuning procedure is a step-by-step approach leading directly to a set of numerical values to be used in a PID controller. These procedures may be split into…
How ANSI Class Relates to PSI ?
Take a look through our website and you’ll see most of our pressure ratings are expressed as PSI - pounds per square inch. In this article, we’d like to talk…
NPT Connection Measurement Size
A 1/4” NPT connection size doesn’t have the 1/4” measurements where you think they would be. In fact, the connection’s outside diameter measures a little more than 1/2" wide. Did…
What is a Y Strainer ?
Y-strainers find their ways into all kinds of applications – including food preparation, cosmetics, diesel engines, and the petroleum industry. Y Strainer : Y-Strainers can be installed horizontally or vertically with…
