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Panel Mounted pH Controller with 2 Control Relays and 4-20mA output

p7635 2 control relays

The P7635 pH Controller is a panel mounting controller with the option of a surface mounting enclosure, part number P7635-W.

P7635 pH Controller Introduction

The P7635 pH Controller is a panel mounting pH controller with a large bright red LED digital display in a DIN spec housing 96 x 96mm and is designed for the DN 47300 standard. This instrument also has a very short case length of only 95mm, allowing the controller to be mounted into compact sized control panels, saving on both space and cost.

pH or Redox Measurement

The P7635 can be selected for use with pH probes, Redox Probes, or with Antimony Electrodes for pH measurement in solutions containing HF (Hydrofluoric acid). The range of the instrument is across the full 0-14.00 pH scale and from 1000mV to +1000mV for the measurement of Redox (ORP). This instrument also has temperature compensation which may be manually set over the range of 0-100ºC or automatically compensated for over the 0-100ºC. The Automatic Temperature Compensation is through the use of either a Pt100 or Pt1000 temperature sensor. These are available from AWE Direct as either a pH Electrode with a built in Temperature Sensor, or as a separate stand alone temperature sensor.

When measuring pH we suggest pairing our instrumentation with an AWE pH electrode or another good quality electrode. For Redox measurement we recommend pairing the P7635 with an AWE Platinum band Redox Probe or another precision Redox probe.

On/Off Control Relays and Alarm Relays

The P7635 is fitted with two programmable On/Off control relays. These can be programmed for either high or low operation and have adjustable delay timers. The On/Off control relays are SPST 5 amp non inductive. Within the instrument, a pH value can be assigned as a setpoint (such as a value of 7.00pH.) When the pH value is below this point, a control relay will switch, allowing a dosing pump to activate or a normally closed solenoid valve to open. When the set point value (eg. pH 7.00) is reached, the control relay will switch again to stop the dosing pump from operating or to return the solenoid valve to closed. In this instance the On/Off control relay is set to low. As the P7635 pH Controller includes 2 x control relays the pH value of the second control relay can be assigned another value. For example this value could be set at 10.00 pH. If the pH is above this value, a second dosing pump or solenoid valve could be controlled to dose an acid to reduce the pH value below the 10.00 pH setpoint. This second On/Off control relay would be set to high. This setup would ensure that in this treatment example the pH value would remain between 7 & 10 pH. In addition to the On/Off control relays, the P7635 includes an alarm relay with adjustable delay timer. This can be set to operate on both a high and low measured value. The alarm relay is often used to control an audible alarm and/or control beacon.

4-20mA output for use with PLC's and Chart Recorders

The P7635 pH Controller has an isolated current output which corresponds to the measuring range selected (either pH Control or Redox Control) and can output either a 0-20mA or a 4-20mA signal. The current output is isolated and often used with a PLC or Chart Recorder.

  • Specifications


    Model No:- P7635

    pH Range:- 0-14.00 pH

    Redox Range:- -1999 to +1999 mV

    Temp. Compensation:- Manual or Auto via 3 wire PT100 or PT1000

    Temp. Range:- -0ºC to 100ºC

    Input:- pH electrode, Antimony pH electrode,

    Redox Electrode

    Set Points:- 2 Min / Max selectable, contact SPST, 5 Amp inductive

    Action:- On/Off with delay timer of 0-100 secs

    Current output:- 0-20 / 4-20mA isolated into 600Ω


    Slope:- 80% - 110%

    Mains Supply:- 85-264 Volt, 50 / 60Hz switch mode power supply

    Power Consumption:- 6 VA

    Weight:- 500 grams DIN version

    Dimensions:- 96 x 96 x 95mm cutout 92 x 92mm

  • Features


    • Short case length pH controller for panel mounting and available in surface mounting enclosure.
    • Precision pH and Redox monitoring for process and effluent applications.
    • Easy to setup, install and use.
    • Bright display for dark installations.
    • ± 0.02 pH hysteresis banding and dual set points, to allow for both Acid and Alkali dosing where the hysteresis can prevent pH correction switching.
    • Isolated current output for data-logging and PLC based applications.
  • Data Sheets

    Data Sheets


More Information