When duplicate pumps are installed, what type of valve is required downstream of each full-flow check valve?

• A. Gate or Ball valve downstream of each full-flow check valve
• B. Globe valve downstream of each full-flow check valve
• C. No valve downstream of a check valve is required
• D. Gate valve downstream only if pumps are not duplicated

Answer: (A)

In a duplicate pump setup, each discharge path needs an isolation valve downstream of its check valve so you can shut off that pump for maintenance without draining the whole system and without letting backflow occur through the other path. Gate or ball valves are preferred for this downstream position because they provide a true, full shut-off with minimal flow resistance when open and quick, reliable operation when closing. Globe valves are more suited to throttling and have more flow resistance and wear in a routine shut-off application, making them less ideal for isolating a pump.