Electronic Pressure Independent Valve (ePIV) are now available in sizes ½” to 6”. The ePIV directly measures flow by combining a magnetic flow meter and a 2-way control valve. The 
actuator has a powerful algorithm that modulates the control valve to maintain the exact flow based on the control signal set by the DDC Controller. The flow reading is reported back to the controller using a standard signal, and this value can be used by the Building Automation System to perform advanced control and energy strategies.
Pressure Independent Valve Comparison
With pressure independent control technology only a single valve is required to maintain proper flow through each circuit. Each valve arrives from the factory pre-set for each circuit, so there is no additional balancing required. The system performs perfectly from start-up. And if a facility adds new circuits as a result of expansion, the flow control of existing circuits remains intact – so no rebalancing is required. Pressure independent valves can be used to regulate flow through air handlers, heating and cooling coils, fan coil units, unit ventilators and VAV re-heat coils.
Valves are selected based on the GPM requirements of the coil and no Cv calculations are needed. By precisely controlling the flow, the pressure independent valves eliminate the need for balancing valves, thus reducing the installation and balancing cost. By far, the biggest benefit for the owner comes in the form of energy savings by eliminating overflow thru the coil. Overflow wastes energy by over pumping and is the main cause of the low ΔT syndrome in chilled water systems.