pH Probe Assembly

The pH600/762 pH probe assembly is a loop-powered, isolated pH sensor, with all power being supplied from the two-wire current loop connection. Isolation enables the probe to be at a potential relative to ground without affecting the integrity of the measurement. The two-wire connection eliminates the requirement of a separate supply in addition to the loop supply voltage.


  • Temperature-compensated pH or ORP measurement.

  • Two-wire field mounted transmitter – suitable for multiple-loop installations with a central controller.

  • Local display of pH/ORP and temperature – suitable for use as a stand-alone pH monitor.

  • Isolated 4-20mA signal.

  • Simple pushbutton operation.

  • Tough IP65 die-cast Aluminium enclosure.

  • Plug and socket connectors for easy installation and maintenance.

  • Tool-free operation – no dip-switches or potentiometers.

  • Suitable for masthead mounting (as pictured) or wall mounting.

With a Model 762 probe assembly and electrodes, the pH600 transmitter becomes a complete pH sensing unit. The pH600 transmitters include all the circuitry necessary for the measurement and transmission of an isolated 4-20mA linear signal. All the transmitter’s functions are accessible through the pushbutton interface – there are no potentiometers or dip-switches. Two-point calibration of the signal is accomplished using the standard calibration routine. The pH600 can also temperature compensate pH readings using a 100Ω TC element.

The Model 762 assembly is manufactured from chemically resistant polypropylene and has spaces for two PG13.5 electrodes – a rugged glass pH electrode and glass temperature compensator. The reference is a double-junction arrangement with a large gel reservoir giving excellent stability in tough applications.

Tecnical Specifications


Range 0.00pH to 14.00pH

Resolution 0.01pH

Accuracy ±0.01pH

Temperature Range -10°C to 110°C

Resolution 0.1°C

Accuracy ±0.5°C

MillivoltRange -1000mV to 1000mV

Resolution 1mV

Accuracy ±2mV


Temperature Compensation Auto (Pt100) / Manual (0° to 100°)

Number of Calibration Points 2

Calibration Buffers 4.01, 7.00, 10.01

Inputs Asymmetrical/Symmetrical

Outputs 4.0mA to 20.0mA

Under-range Current Output 3.8mA/4mA (selectable)

Over-range Current Output 3.8mA/20mA (selectable)

Hold Current Output 22mA/Last Value (selectable)

Display Custom LCD

Power Requirements 12V to 24V dc

Load Resistance 600 ohm Max

Ordering Information

500/0034 Complete pH probe assembly: pH600, 762 holder, electrodes and 40cm wand

Part of the SDI group

Astles Control Systems Ltd

B3 Regent Park, Summerlys Road,

Princes Risborough, Bucks, HP27 9LE

t: 01844 273301


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