The EvoPICV Pressure Independent Control Valve “PICV” is a combined constant flow limiter and full stroke, full authority equal percentage temperature control valve.
The EvoPICV is suitable for use in variable and constant temperature systems and may be used as constant flow limiter in constant volume systems (without an actuator head) or as a true PICV in variable volume systems.
Operating principle
EvoPICV valve is made by three main parts:
differential pressure regulator
regulating valve for flow adjustment
flow pre-setting knob
1. Differential pressure regulator
The differential pressure regulator is the heart of the pressure independent control valve. By keeping a constant differential pressure across the valve seats constant flow and full authority temperature control can be achieved.
Incoming pressure P1 is transmitted to the top face of the diaphragm, outgoing pressure P3 is transmitted to the underside of this same diaphragm. A constant effective differential pressure is maintained between P2 and P3. As P1 increases relative to P3 it acts on the diaphragm closing the shutter (A) against a seat (B) thereby lowering the effective differential pressure. As P1 decreases relative to P3 the diaphragm acts to open the shutter (A) from the seat (B) thus increasing the effective differential pressure. The diaphragm acts against a spring in order to balance the pressure control and stop the diaphragm oscillating.
2. Regulation valve
Water flow through a valve varies as a function of the area of passage and the pressure differential across that valve. Due to the incorporation of the differential pressure regulator the differential across the valve seats P2 - P3 is constant meaning that flow is now only a function of area of passage.
Setting any flow rate value and maintaining it stable is also possible. The regulation valve presents an equal percentage characteristic.
3. Adjustment knob
The maximum value of the flow can be preset, choking the outlet section of the control valve, using the graduated adjustment knob.
The percentage value, indicated on the scale, matches the maximum flow rate percentage. This value can be changed turning the adjustment knob until it reaches the selected position (matching the percentage indicated on the scale). A locking mechanism avoids the valve set values from being changed inadvertently.
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