If the standpipe riser is PRV'd and the building exceeds 10 stories, the pump should be operated in which mode?

If the standpipe riser is PRV'd and the building exceeds 10 stories, the pump should be operated in which mode?

• A. Volume mode
• B. Pressure mode
• C. Idle mode
• D. Off

Answer: (B)

When a standpipe riser has a pressure reducing valve and the building is tall (over 10 stories), the pump needs to keep the outlet pressure at a reliable, usable level on all floors. This is best achieved by running the pump in pressure mode. Pressure mode maintains a target discharge pressure at the outlets regardless of changes in demand, which is crucial for upper floors where elevation and friction losses can otherwise drop pressure. Volume mode would push a certain amount of water but could let pressure sag on higher levels, making firefighting less effective. Idle or off would provide no active protection during an incident. So the pump should be operated in pressure mode to ensure consistent, adequate pressure throughout the standpipe system.

When a standpipe riser has a pressure reducing valve and the building is tall (over 10 stories), the pump needs to keep the outlet pressure at a reliable, usable level on all floors. This is best achieved by running the pump in pressure mode. Pressure mode maintains a target discharge pressure at the outlets regardless of changes in demand, which is crucial for upper floors where elevation and friction losses can otherwise drop pressure. Volume mode would push a certain amount of water but could let pressure sag on higher levels, making firefighting less effective. Idle or off would provide no active protection during an incident. So the pump should be operated in pressure mode to ensure consistent, adequate pressure throughout the standpipe system.