642 Industrial pH Sensor – TOP SELLER

/642 Industrial pH Sensor – TOP SELLER

642 Industrial pH Sensor – TOP SELLER

Process Combination pH or ORP Sensor

The IC Controls model 642 pH sensor (642-4P = ORP sensor) is a low-cost solution to traditional leakage problems associated with submersible pH and ORP sensors.

Reliable Submersion

The IC Controls model 642 pH sensor is a low-cost solution to traditional leakage problems associated with submersible pH sensors. The sensor assembly is designed to work with the electronics package located in a junction box above the liquid level. The assembly is completely encapsulated and comes with a standard 3 meter (10 foot) lead. This setup achieves a reliability not previously associated with submersion pH measurement.


  • Rugged body constructed from 2.5 cm (1 inch) schedule 80 pipe
  • Cushion-mounted pH electrode resists shocks
  • “U” shaped body protects glass tip from breakage during calibration, cleaning and accidental impact.
  • Open electrode tip for easy cleaning
  • Large 2.5 cm (1 inch) diameter reference junction surrounding pH tip resists plugging and eliminates variations in reading caused by changes in flow direction.




Why We Designed the 642

A major mining company asked IC Controls to design a pH sensor to survive pH measurement problems they had in gutters, sluiceways, and flotation tanks. Rock slurry not only precipitated scale on their pH sensor; it also hit the sensors with pieces of lumber and packed broken wood fragments around the pH tip. They wanted a robust survivor, they wanted a sensor from which it is easy to remove scale and debris packed in around the pH tip. To answer the mining company’s needs, IC Controls developed the model 642 sensor from heavy-walled pipe with body extensions to protect the glass pH tip from direct impact. This sensor is rugged! Internally the pH glass was cushion-mounted so that impact does not break the glass. To address the scaling and junction-plugging problem, a wood junction was employed to leverage its unique ability to resist plugging in high dirt or fibre applications. A 2.5 cm (1 inch) junction diameter was chosen so that a typical screwdriver blade can be used to scrape away scale and debris off the junction or pH glass tip. Finally, the pH glass was recessed in a protective pocket of heavy body flutes. Now the sensor was sufficiently protected that it could resist an accidental drop on the floor, or be placed in the bottom of a pail of acid for scale removal, or in a pot of pH buffer for calibration. Properly positioned, the body flutes also scoop just enough particulate to wear down scale as fast as it is formed.

Selection Guide
User Manual
Engineering Specifications
Mounting Options
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pH/ORP Sensors in Metallurgical Applications

Critical Elements of the Sensor, Material Selection, Sensor Size Matters, Keeping Contaminants Out, Taking the Heat, Direct Connect versus Preamp.
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Download Article

pH Theory and Measurement

What is pH? Mathematical and descriptive definition, pH measurement techniques, pH sensing electrode, glass electrode, how glass electrodes work, types of glass electrodes, temperature affects on glass, reference electrode, referenced junction impact, ceramic junctions, wood junctions, etc.
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Download Questionnaire (PDF)

Complete & Submit Questionnaire Now

The Model 642 sensor is used in “the refinery where it is really abrasive, high acid, and high temperatures.  The competition claim they can take the high temperatures and high acid environments, but their probes are failing all over the place in those applications.”

from an Instrumentation Technician using our top selling pH Sensor, the Model 642 in their mining application.
October 2014

“After 8 years in application, this satisfied customer does not need to replace his sensor that is still working well in application, but is looking to upgrade his electronics to our new Model 210 series.”

from a customer using our Flanged 642 pH sensor/electrode in a Chlor Alkali plant.
November 2011

“Your pH sensor was one of the best in our trial.”

from a Waste Water Treatment Plant Operator 
August 2010

We were contacted for a quote to replace an IC Controls pH probe.  When given the serial number, we were astounded to learn the probe had been in service for 15 years!

from a Process Engineer at a steel company
October 2009

“I am quite pleased with the pH probes we purchased some time ago from IC.  In the near future we will be looking at the Total Chlorine pH/ORP method analyzers.”

from an Instrumentation and Controls Technician at a local city installation
May 2008

Wiring Diagram

pH Sensor to Analyzer Connection

Electrical Schematic for Model 602, 605, 606, 607, 614, 615, 617, 625, 627, 642, 643 and 648
Wiring Diagram
Dimensional Drawing

pH sensor with flange

Option -23, 2 inch 150 lb CPVC flange.
Dimensional Drawing
Dimensional Drawing

Chemical cleaner nozzle

A2100020 = option -78 and -79 (required) for model 642 pH sensor.
Dimensional Drawing
Assembly Drawing

Swing arm kit

A2100061 = PVC swing arm kit with 9 ft chain, option -3 for model 802 DO sensor and 642 pH sensor.
Assembly Drawing