In an alarm valve with a retard chamber in the trim, which switch should be used on the alarm line?

In an alarm valve with a retard chamber in the trim, which switch should be used on the alarm line?

• A. Pressure switch
• B. Flow switch
• C. Temperature switch
• D. Proximity switch

Answer: (A)

The alarm line needs a signal that comes from pressure in the line when the valve operates. A pressure switch is designed to sense that line pressure and close or open a circuit to the fire alarm system, triggering the alarm appropriately. The retard chamber in the trim slows the valve’s action a bit, allowing the pressure in the alarm line to rise and remain present long enough for the switch to reliably trip, which helps prevent false alarms and ensures the alarm signal is clean. A flow switch would react to water movement, not the pressure signal needed for the alarm line; a temperature switch responds to heat, and a proximity switch isn’t the standard choice for signaling the alarm line in this setup.

The alarm line needs a signal that comes from pressure in the line when the valve operates. A pressure switch is designed to sense that line pressure and close or open a circuit to the fire alarm system, triggering the alarm appropriately. The retard chamber in the trim slows the valve’s action a bit, allowing the pressure in the alarm line to rise and remain present long enough for the switch to reliably trip, which helps prevent false alarms and ensures the alarm signal is clean. A flow switch would react to water movement, not the pressure signal needed for the alarm line; a temperature switch responds to heat, and a proximity switch isn’t the standard choice for signaling the alarm line in this setup.