Which statement about pressure-independent balancing valves is true?

Which statement about pressure-independent balancing valves is true?

• A. They maintain a constant pressure across the valve to stabilize flow.
• B. They are used only in central plant systems.
• C. They respond to changes in system pressure without user adjustment.
• D. They adjust automatically to variable loads by sensing flow and maintaining constant flow.

Answer: (D)

Pressure-independent balancing valves keep the flow through a branch fixed even when system pressure changes. They do this by automatically adjusting the valve opening in response to the actual demand, so the set flow rate is maintained as loads vary. This automatic flow regulation is what makes them useful in systems with fluctuating pressures or changing loads (like VAV zones or terminals). The statement that best captures this is that these valves adjust automatically to variable loads by sensing flow and maintaining a constant flow. They’re designed to respond to how much flow is needed, not to hold a constant pressure, and they’re commonly used on individual branches or terminal units rather than only in central plant systems.

Pressure-independent balancing valves keep the flow through a branch fixed even when system pressure changes. They do this by automatically adjusting the valve opening in response to the actual demand, so the set flow rate is maintained as loads vary. This automatic flow regulation is what makes them useful in systems with fluctuating pressures or changing loads (like VAV zones or terminals).

The statement that best captures this is that these valves adjust automatically to variable loads by sensing flow and maintaining a constant flow. They’re designed to respond to how much flow is needed, not to hold a constant pressure, and they’re commonly used on individual branches or terminal units rather than only in central plant systems.