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Installation and Operating Instructions
Commissioning
The Fig. 1934 controls the flow rate depending on its set position, therefore,
removing the need to measure the flow rate.
The Fig. 1934 maintains a constant differential pressure across its internal
seat, any excess pressure being removed by the internal differential pressure
controller.
To ensure that sufficient pressure is available for the differential pressure
controller to control the flow rate correctly, a differential pressure reading
should be taken using the test points provided.
When taking differential pressure readings, it is important that the system
is running at full load, i.e. at their set position. This ensures that differential
pressure readings are carried out in the most unfavourable conditions,
guaranteeing optimum performance in normal running conditions.
To ensure that all PICVs are working at the required differential pressure, it
is necessary to check the least favoured / index PICV. By verifying the least
favoured PICV is set to the required differential pressure, all other PICVs must
have a higher differential pressure. However, we would also recommend that
a selection of other PICVs are tested along the circuit to verify this.
Hattersley – Pressure Independent Control Valve – Fig. 1934
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