What are the most important process variables?

 You may name many variables as related to a control loop. However, there is a small set of process variables that we may recognize as the most important.

Which features we should look for in these important variables

• These variables are common to almost all chemical processes.
• Other variables of the process can be controlled by manipulating this ones.
• There is plenty of instruments with different technology to measure these process variables.
• You may find cheap instrument options in the market to make a control loop with these process variables.
• These variables may be found as controlled variables but also as the manipulated variables.

The most important variables in a control loop

• Pressure
• Temperature
• Flow rate
• Level

The most important process variables in control loops

Any question? Write in the comments and I shall try to help.

Other stuff of interest

• LE01 - AC and DC voltage measurement and continuity test
• LE 02 - Start and stop push button installation 24V DC
• LE 03 - Turn on/off an 24V DC pilot light with a push button
• LE 04 - Latch contact with encapsulated relay for turning on/off an AC bulb light
• About PID controllers
• Ways to control a process
• About pilot lights
• Solving the Colebrook equation

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Ildebrando.