Pulse Instruments
System 4 Manual
Version 1.6
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Hysteresis / dead-band eliminate output chatter at the switch point (See Fig. 9).
Fig. 9 Hysteresis / Dead-band
4.2 Monitoring
This system monitors pH, ORP, and Temperature. pH is in the range of 0 to 14. ORP is in the
range of 0 to 1000 mV and temperature is in the range of -58 ºF to 1832 ºF using a Type J
thermocouple.
The operator interface (See Fig. 2) panel allows user friendly messaging for ease of use and
operation. It displays the pH and ORP control and alarm set points, as well as messaging for
alarm conditions and water fault in case of flow failure. New set point values may be entered
here and executed for operation.
Three color-coded warning lights indicate alarm states and conditions of the system by either
steady or flashing lights and color-coding. Pushbuttons on the panel allow for alarm resetting,
alarm silence and menu function access and selection.
4.3 Control
4.3.1 pH / ORP
Under normal conditions, pH is controlled by the system to the desired pH value set through the
operator interface. When the pH rises above the high set point value, the acid pump will
automatically turn on via a control relay. Acid is added to the water until the pH drops down to
the set point value, and the acid pump shuts off. The corresponding status indicator light will turn
on to indicate the pump is ON.
Under normal conditions, the oxidation pump is controlled by the system to the ORP value set
through the operator interface. When the ORP value drops below the low set point value, the
oxidation pump automatically turns on via a control relay. The pump adds oxidizer to the water
until the ORP value rises to the set point value, and then shuts off. The corresponding indicator
light will turn ON to indicate the pump is ON.
4.3.2 Proportional
Control
Proportional control has the ability to increase or decrease the speed of the pump in relation to
the set point value by using a 4-20 mA signal. In order to proportionally control the chemical
metering pumps for acid and oxidation injection, the chemical metering pumps must be
connected to the ON / OFF control outputs and to the 4-20 mA signals from the control panel.
The system is able to turn ON or turn OFF the chemical metering pumps to inject chemical at the
specified set point values. The 4-20 mA output signals span the pH and ORP scales, 0 – 14 pH
and 0 – 1000 mV, respectively. See Section 6.4.2 for configuration details.
SP = Setpoint
Hys = Hysteresis
