Pressure Independent Control Valves

A pressure independent control valve (PICV) combines a differential pressure regulator, a flow limiter and a modulating control valve in one body, so the flow through a terminal unit stays at its set value while pressure elsewhere in the network changes. Seven Star LLC supplies PICVs in Oman from Belimo, Danfoss, Siemens, Frese and IMI TA.

Six valve series are listed, from small threaded valves for fan coil units to flanged valves for air handling units and plant rooms. The range is growing.

PICV types listed: mechanical, electronic and energy valves

The Danfoss AB-QM, Frese OPTIMA Compact, Siemens VPI46 and IMI TA-COMPACT-P are mechanical pressure independent valves. A built-in differential pressure regulator holds a constant pressure across the control seat, and the maximum flow is preset on the valve. The Belimo EPIV works differently: it measures flow with a built-in sensor and the actuator corrects the valve position electronically to hold the flow set point. The Belimo Energy Valve adds a thermal energy meter with supply and return temperature measurement, so it can report energy use as well as control flow.

Selecting a PICV for chilled water systems

Selection is based on design flow, not on a Kv calculation as with a conventional valve. Choose the valve size whose flow range contains the design flow, ideally away from the bottom of its setting range. Check that the pump provides at least the minimum differential pressure the valve needs to regulate, and that the maximum differential pressure in the system is within the valve’s limit. Then match the actuator: on-off thermal actuators for simple fan coil control, modulating or bus actuators for air handling units. In buildings across the GCC, where chilled water runs for most of the year, stable flow and a healthy temperature difference at the chillers are the main reasons consultants specify PICVs.

What to send for a PICV or FCU valve kit quotation

Send the valve schedule with design flow per unit, pipe size and connection type, system pressure rating, the control signal and voltage of the actuators, and quantities. If you need complete fan coil unit valve kits, list the other parts wanted, such as isolation valves, strainer, test points and flexible hoses, and the specified brand. We check each selection against the manufacturer documentation.