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Valves practice questions

20 questions from the pipefitting and steamfitting practice test.

Valves practice test

10 questions, graded as you go, with the reason for every answer. No sign-up.

What this covers

Sample questions

In which position can a standard swing check valve be installed in a vertical line?

  1. Only with the flow going downward
  2. Only with the flow going upward
  3. With flow in either direction
  4. It cannot be used in vertical lines
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B. Only with the flow going upward

In a vertical line with upward flow, gravity swings the disc back onto its seat when flow stops. With downward flow gravity would hold the disc open and the valve could not check.

Reference: Check valve installation orientation

Why is a spring-loaded (silent) check valve often chosen for a pump discharge instead of a swing check?

  1. It has a much lower pressure drop when it is fully open
  2. It can be throttled by hand to balance the pump flow
  3. It closes before the flow reverses, which prevents slam
  4. It needs no particular direction of flow through it
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C. It closes before the flow reverses, which prevents slam

The spring closes the disc as the flow slows to zero, so there is no reverse flow to slam it shut and cause water hammer. The trade-off is a somewhat higher pressure drop than a swing check.

Reference: Check valve selection: center-guided spring checks

What can you tell at a glance from an outside screw and yoke (OS&Y) gate valve?

  1. Whether the valve is open or closed
  2. Which direction the fluid is flowing
  3. What the pressure is inside the line
  4. Whether the packing needs replacing
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A. Whether the valve is open or closed

On an OS&Y valve the threaded stem rises out of the handwheel as the valve opens, so a raised stem means open. That visible indication is why OS&Y valves are required as control valves on fire protection systems.

Reference: Gate valve stem types: OS&Y

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