PH/PHX-2 Manual
9
Pressure Balance Control System
The Pressure Balance Control (PBC) system performs an automatic shutdown when a chemical
imbalance occurs. When the system is turned off, the Proportioner will perform as if there is no PBC
system and will continue pumping material. When the system is turned on, it will continually monitor the
pressure between the two chemicals (known as the pressure differential). If the pressure differential
becomes equal to or greater than the maximum allowable pressure differential, the pumps will be shut
off.
The Pressure Balance Control system can be simplified into a logic box diagram with inputs and outputs.
There are five inputs: the power supply from the main console, the pressure readings from each
chemical, the maximum pressure, and the maximum allowable pressure differential. Inside the logic box,
the actual pressure differential of the chemicals is compared to the maximum allowable pressure
differential. Depending on the circumstances of all five inputs, there are only two possible outputs: either
the pumps will continue to pressurize and move material, or the pumps will shut off and flow will be lost.
Logic Box Representation
1. Power supply
2. “A” side pressure reading
3. “R” side pressure reading
4. Maximum pressure
5. Maximum allowable
pressure differential
Logic Box
1. Continue pumping material
OR
2. Shut off pumps
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