Question 265General Subjects - Assistant Engineer
70% to passReferring to the illustrated pneumatically operated diaphragm actuated control valve, what statement is true? Illustration GS-0051
AThe control valve is direct-acting and normally open (NO).
BThe control valve is indirect-acting and normally open (NO).
CThe control valve is direct-acting and normally closed (NC).
DThe control valve is indirect-acting and normally closed (NC).
AI Explanation
The correct answer is A) The control valve is direct-acting and normally open (NO). In a direct-acting pneumatic diaphragm control valve, the valve opens when the pneumatic signal increases, allowing flow through the valve. This is the normal operating condition, so the valve is normally open (NO). The other options are incorrect because an indirect-acting valve would close when the pneumatic signal increases, and a normally closed (NC) valve would be closed in its normal state without an actuating signal.
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