This type of valve reduces the differential pressure across the closed disk and makes the main valve easier to open and close.

• A. Bypass valve
• B. Gate valve
• C. Globe valve
• D. Check valve

Answer: (A)

Equalizing pressure around the shutoff valve to reduce the force needed to move the disk. A bypass valve provides an alternate path around the main valve so some flow can bypass it and balance pressure on both sides of the closed disk. With the pressures more even, the main valve requires less effort to open or close, and the wear and sticking risk decreases, which is especially helpful on large or high-pressure lines. The other valves don’t provide this pressure relief function: the main function of a gate valve is to stop or start flow, a globe valve typically creates a larger pressure drop and is used for throttling, and a check valve prevents backflow.