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8. PUMP CONTROL
Pump control can be enabled, automatic control (AUTO) or disabled (off).
See SETUP section for further details on how to enable or disable pump control.
LCD backlight color indicates the pump control status:
• green - automatic control or in View menu mode
• yellow - disabled or in Edit menu mode
On the LCD screen, the pump status is displayed as below:
Startup Delay (Automatic Control Only)
When Startup Delay option is enabled, the controller is in Control Off mode for the set time; and the
LCD backlight color is orange. The delay countdown will start upon powering the controller. At the end
of the timing the LCD backlight turns green and the control mode is automatic (Auto).
8.1. AUTOMATIC CONTROL TYPES
There are two automatic control types: On/Off (constant) control and proportional control.
On/Off control
With On/Off control type for pH enabled in SETUP, the algorithm uses only "set point" and "hysteresis",
both with user-selectable values. See SETUP section for further details.
High control mode: When the process pH drifts upward and it reaches a high set point, it triggers the
reagent pump to turn on and acid can be added to decrease the pH. The pump will remain on until
the pH has decreased to the set point value minus the hysteresis value. Then the pump will shut off.
Low Control mode: Conversely, with Low control mode, the process pH drifts down until it reaches
a low set point. This triggers the pump to turn on and a base can be added to increase the pH. The
pump will remain on until the pH has increased to the set point value plus the hysteresis value. Then
the pump will shut off.
The typical application uses a high control point with the addition of an acid.
oFF, no dosing
AUTO, dosing
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