Control Valve · Glossary

What is Valve Stiction?

static frictionControl Valve

Valve stiction is static friction that makes a valve stick, then jump, instead of moving smoothly, causing control loops to cycle.

Valve Stiction Explained

When the controller output changes slightly, a sticky valve does not move until enough force builds up; then it jumps past the needed position. The loop then cycles around set point.

Tight packing, damaged stems and undersized actuators are common causes. Valve signatures and loop data analysis reveal it.

Valve Stiction: Typical Values

Typical symptom	square wave valve position with triangular process value cycling
Common fixes	packing service, correct actuator, positioner tuning

Calculators for Valve Stiction

CalculatorActuator Thrust CalculatorFree online calculator with formula and worked example.CalculatorControl Valve Opening CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadControl Valve Stroke Test ProcedureFree step by step procedure, Word and PDF.

Frequently Asked Questions

What is Valve Stiction?

Valve stiction is static friction that makes a valve stick, then jump, instead of moving smoothly, causing control loops to cycle.

Can tuning fix stiction?

Detuning reduces the amplitude but not the cause; fix the valve.

Is stiction the same as deadband?

They are related: deadband is a range where input changes give no movement; stiction adds the jump.

Learn more on the blog

Control valve positioner working

A practical guide on instrumentationblog.in with more detail on valve stiction and how it is applied on real plants.

Read Full Article

More Control Valve Terms

Valve termSplit Range ControlSplit range control uses one controller output to operate two valves, each over part of the signal range.Valve termStroke TimeStroke time is the time a valve takes to move from fully open to fully closed, or the reverse, after a…Valve termPartial Stroke TestingPartial stroke testing moves a shutdown valve a small amount, typically 10 to 20 %, to prove it is not…Valve termGlobe ValveA globe valve is a linear motion valve where a plug moves towards or away from a seat; it is the classic…Valve termButterfly ValveA butterfly valve is a quarter turn valve with a disc that rotates in the flow path; it is compact and…Valve termBall ValveA ball valve uses a rotating ball with a bore to control or stop flow; segmented V ball designs are used…

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