In a balance-pressure system, which device maintains automatically the equal pressures between foam concentrate and water when using a pump discharging through a metering orifice into a controller?

In a balance-pressure system, which device maintains automatically the equal pressures between foam concentrate and water when using a pump discharging through a metering orifice into a controller?

• A. A pressure balancing valve.
• B. A relief valve.
• C. A check valve.
• D. A diaphragm.

Answer: (A)

Balance-pressure systems rely on automatically equalizing the pressure on the foam concentrate line to the water line so the metering orifice sees a consistent driving pressure and the foam solution is proportioned correctly. The device that does this automatically is a pressure-balancing valve. It sits in the concentrate supply and senses the water line pressure; as water pressure changes, it adjusts concentrate flow to keep the two pressures essentially equal. This keeps the metering action stable across varying demands, preventing over- or under-proportioned foam. A relief valve would vent excess pressure and doesn’t maintain equal pressures between the two streams; a check valve prevents backflow but doesn’t balance pressures; a diaphragm is a component inside some valves but not the balancing device itself.

Balance-pressure systems rely on automatically equalizing the pressure on the foam concentrate line to the water line so the metering orifice sees a consistent driving pressure and the foam solution is proportioned correctly. The device that does this automatically is a pressure-balancing valve. It sits in the concentrate supply and senses the water line pressure; as water pressure changes, it adjusts concentrate flow to keep the two pressures essentially equal. This keeps the metering action stable across varying demands, preventing over- or under-proportioned foam. A relief valve would vent excess pressure and doesn’t maintain equal pressures between the two streams; a check valve prevents backflow but doesn’t balance pressures; a diaphragm is a component inside some valves but not the balancing device itself.