OxyGuard pH Plus

The OxyGuard pH Plus is a single channel pH measurement and control transmitter with automatic temperature compensation. It has built-in pulse controller, 4-20 mA analogue output and both high and low alarm outputs and is intended for use as a pH meter, monitor and controller in industrial and other uses.

As with all OxyGuard pH systems, a system using the pH Plus is not prone to problems caused by moisture or electrical noise. The latter is solved so effectively that ordinary screened cable can be used between the probe and transmitter.

pH Plus is used with an OxyGuard pH probe. There are several types, for both simple and more demanding measurement tasks in a large variety of mounting forms.

The OxyGuard pH Alpha is available for users needing a primary pH measurement device without alarm and control functions.

Technical Advantages

Waterproof metal cabinet with a clear plastic lid covering the front panel. Adjustments are situated on the front panel - "SLOPE" and "ZERO" for calibrating the electrode, "LO" "HI" and "CON" for the alarm and control output set points and "PULSE TIME" to set the pulse time of the control output. A set point value is indicated on the display when the pushbutton under the appropriate set point adjustment is depressed. Temperature (if measured) is displayed when a fourth pushbutton is pressed. Three red LED indicators show when an alarm or control output is active.

The unit can be used with or without a temperature measurement. When used with a temperature measurement the unit automatically compensates for the temperature error of the pH electrode. The measured temperature is shown on the display when the "READ TEMP" pushbutton is pressed. When used without a temperature measurement the temperature at which pH measurements are made is set using a small trimpotentiometer behind the front panel.


The OxyGuard pH Plus is designed for use with the range of pH Probes. These are available in two main categories. Light-duty probes have gelled electrolyte combination electrodes that are suited to the more "harmless" process fluids. Heavy-duty probes have combination electrodes to which liquid reference electrolyte is fed continuously, extending probe lifetime in most "difficult" fluids. Each is available in a variety of immersion, submersion and flow-through versions in different materials - they are described in separate brochures. All OxyGuard pH probes are designed so that moisture problems are eliminated, and the inclusion of an impedance converter immediately above the electrode effectively prevents electrical noise problems. The result is an accurate, very reliable and exceptionally easy to use system.