Question 263General Subjects - Assistant Engineer

70% to pass

Assuming that the flow is from left to right on the illustrated pneumatically operated diaphragm actuated control valve, what statement is true? Illustration GS-0051

Diagram for USCG General Subjects Assistant: Assuming that the flow is from left to right on the illustrated pneumatically...

AInlet pressure acts on the upper surface of the top disc and the lower surface of the bottom disc for the purpose of achieving hydraulic balance so that inlet pressure does not influence the valve position.

BInlet pressure acts on the lower surface of the top disc and the upper surface of the bottom disc for the purpose of achieving hydraulic balance so that inlet pressure does not influence the valve position.

CInlet pressure acts on the upper surface of the top disc and the upper surface of the bottom disc for the purpose of achieving a hydraulic assist to aid in valve closing.

DInlet pressure acts on the lower surface of the top disc and the lower surface of the bottom disc for the purpose of achieving a hydraulic assist to aid in valve opening.

AI Explanation

The correct answer is B) Inlet pressure acts on the lower surface of the top disc and the upper surface of the bottom disc for the purpose of achieving hydraulic balance so that inlet pressure does not influence the valve position. This is correct because in a pneumatically operated diaphragm actuated control valve, the inlet pressure is designed to act on the opposing surfaces of the top and bottom discs. This creates a hydraulic balance, ensuring that the inlet pressure does not impact the positioning of the valve. The other answer choices do not accurately describe the inlet pressure acting on the disc surfaces to achieve this hydraulic balance.