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AutoQuiz: In What Position Does a Control Valve with a Direct Acting Actuator Fail?

The post AutoQuiz: In What Position Does a Control Valve with a Direct Acting Actuator Fail? first appeared on the ISA Interchange blog site.

AutoQuiz is edited by Joel Don, ISA’s community manager.

Today’s automation industry quiz question comes from the ISA Certified Control Systems Technician (CCST) program. Certified Control System Technicians calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables. Click this link for information about the CCST program. This question is from the Level I study guide, Domain 2, Loop checking. Level I (Level I represents a professional who has a five-year total of education, training, and/or experience.)

AutoQuiz-20160930-Position-Control-Valve-Direct-Acting-Actuator

A control valve with a direct acting actuator and direct trim will:

a) fail closed
b) maintain position
c) fail open
d) not fail
e) none of the above

   

<span class="collapseomatic " id="id5674" tabindex="0" title="Click Here to Reveal the Answer” >Click Here to Reveal the Answer

A direct acting valve travels to the closed position when the signal increases. When there is a failure, there is no signal and power, and the direct acting valve fails open.

The best answer is C, fail open.

Source: ISA News