Calibration Sales Control Validation Documentation

Product Sales

Hach/GLI Encapsulated Differential pH and ORP Sensors


Differential Electrode Measurement Technique
This field-proven technique uses three electrodes instead of the two normally used in conventional pH sensors. Process and reference electrodes measure the pH differentially with respect to a third ground electrode. The end result is unsurpassed measurement accuracy, reduced reference junction potential, and elimination of sensor ground loops. These sensors provide greater reliability, resulting in less downtime and maintenance.

Complete Encapsulation
Complete encapsulated construction protects the sensor’s built-in electronics from moisture and humidity problems, extending the working life of the sensor.

Built-in Preamp or Two-wire Transmitter
The built-in preamp produces a strong signal, enabling you to locate the analyzer up to 3000 ft. (914 m) from the sensor. An optional built-in two-wire transmitter is available for applications requiring a 4-20 mA sensor signal. This option requires that the indicating instrument of the measuring system be capable of providing 24 VDC to power the sensor, and have adjustment means to calibrate for zero offset and span.

Versatile Mounting Styles
Threads are provided on both ends of the convertible mounting style sensor for either mounting into a pipe tee or attaching to the end of a pipe for immersion. The convertible style enables you to consolidate inventory, and thereby reduce associated costs. A union-mount style sensor and mounting tee are also available to conveniently install and remove the sensor for in-line service.


Chemically-resistant LCP Body.
The exceptional chemical resistance and mechanical strength of the LCP (liquid crystal polymer) sensor body makes it ideal for most applications. These sensors can be used in aggressive process solutions such as acids, bases, alcohols, hydrocarbons, aromatics, chlorinated hydrocarbons, esters, ketones, and most other chemicals. „

Low Heat Distortion.
LCP sensors are physically stable and will not expand or contract when subjected to the heating and cooling cycles of a process. Furthermore, these sensors may be installed in metal fittings without fear of leakage, normally a problem when dissimilar materials are threaded together

Excellent, Strong Base Chemical Compatibility.
The Ryton sensor is best suited for measuring strong base solutions of more than 12 pH at elevated temperatures. It can also be used in acidic solutions, but is not recommended when aromatic hydrocarbons are present.

  • Performance
  • Specs
  • Input/Output
  • Ordering
  • Accessories
  • Engineering
  • Dimensions
Pressure/Temperature Limits:
Sensor Only (no hardware):
LCP Sensor ............................... -5°C (23°F) to 95°C
Ryton Sensor ............................. -5°C (23°F) to 95°C
Sensor with Hardware* .................... See graph below for specific GLI sensor and mounting hardware combinations
* An LCP or Ryton-encapsulated sensor that is mounted in a plastic flow-through tee has a higher pressure rating at maximum temperature than when it is mounted in a union tee. The temperature rating is increased to 95°C at 100 psig when the sensor is mounted in a stainless steel flow-through or union tee, or a stainless steel cross.


1. Most pH applications fall in the 2.5-12.5 pH range. General purpose pH glass electrodes perform well in this range. For pH applications below 4 or above 10 pH, GLI recommends using an LCP-bodied pH sensor. Some industrial applications require accurate measurement and control below 2 or above 12 pH. In these cases, please contact GLI for further details. Repeatability and speed of response of a pH sensor with an optional antimony process electrode is not as good as a sensor with a glass process electrode. Antimony electrodes are only linear between 3 and 8 pH, and should only be ordered when process conditions, such as the presence of hydrofluoric acid, dictate their use.

2. For ORP applications where zinc, cyanide, cadmium, or nickel are present, specify the optional gold electrode instead of the standard platinum electrode.

3. A pH sensor with a built-in two-wire transmitter provides a non-isolated and uncalibrated 4-20 mA output. The indicating instrument of the measuring system must be able

To learn more, contact IIS at 1-877-215-9090 or 732-815-9090.

Subscribe for News & Specials

manu Sales & Service


Industrial Instrumentation Services, Inc.
1400 Rahway Avenue, Avenel, NJ 07001-2214
P: 732-815-9090 F: 732-815-9092
Toll Free: 877-215-9090