If the system has been in extended shutdown, what is advised about pump discharge valves?

If the system has been in extended shutdown, what is advised about pump discharge valves?

• A. Defeat automatic opening of pump discharge valves if the system has been in an extended shutdown. Open valves manually, and slowly, at the local operator.
• B. Leave automatic opening enabled and open quickly.
• C. Remove discharge valves to avoid hammer.
• D. Open discharge valves immediately to full open.

Answer: (A)

Restarting a pump after a long shutdown carries a real risk of water hammer if the discharge valve opens too quickly. By defeating the automatic opening, the valve isn’t slammed open as soon as the pump starts; instead, an operator can slowly open it and let the flow ramp up in a controlled way. This gradual approach reduces the sudden pressure rise that causes hammer and minimizes stress on the pump, valve, and piping. Opening quickly or to full open, or removing valves, would produce large surge pressures or introduce unnecessary risk and is not advisable. Venting air and watching pressures as the pump comes up to speed helps ensure a smooth return to service.

Restarting a pump after a long shutdown carries a real risk of water hammer if the discharge valve opens too quickly. By defeating the automatic opening, the valve isn’t slammed open as soon as the pump starts; instead, an operator can slowly open it and let the flow ramp up in a controlled way. This gradual approach reduces the sudden pressure rise that causes hammer and minimizes stress on the pump, valve, and piping. Opening quickly or to full open, or removing valves, would produce large surge pressures or introduce unnecessary risk and is not advisable. Venting air and watching pressures as the pump comes up to speed helps ensure a smooth return to service.