installation &
operating instructions
Design Envelope 4322 & 4372
Tango Pumping Unit
52
5.14 bypass valve control
The bypass valve control is used to protect flow sensitive equip-
ment (such as chillers). If the flow is less than Setpoint 1, the depc
analog output sends 20mA to fully open the valve. If the flow is
greater than Setpoint 2, the depc analog output sends 4mA to
fully close the valve. There should be a sucient gap between
Setpoint 1 and 2 Flows to prevent the bypass valve from opening
and closing unnecessarily. The recommended bypass valve is a
modulating non-spring return valve (normally closed) with either
4-20mA analog input, or 2-10 Vdc analog input (requires adding
500ohm resistor across the valve input).
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