Why pH is Important

The pH or acidity of a solution is important in many different areas:
In Biochemistry ...The pH of our blood is normally controlled to within a few tenths of a pH unit by our body chemistry. If our blood pH changes as much as half a pH unit, serious illness will result. Proper skin pH is essential for a healthy complexion. The pH of one's stomach directly affects the digestive process.

In Agronomy ...The pH of the soil regulates the availability of nutrients for plant growth, as well as the activity of soil bacteria. In alkaline soils ( pH 8 and above ) the amount of nitrogen, phosphorus, iron and other nutrients in solution become so low that special treatment is necessary to insure proper growth.

In Food Science ...The efficient production of food products depends upon careful pH control. The proper curd size, uniformity, and structure of cottage cheese are directly related to the pH at cutting time. Yeast can ferment and leaven dough only within certain pH limits. Jelly will not gel properly unless the pH is in the 3.5 region.
In Chemical Research and Engineering ...Accurate pH measurement is necessary to the study of many chemical processes. The researcher needs to know the pH at which a chemical reaction proceeds at its fastest in order. to understand the reaction. The engineer uses the information to develop practical commercial processes.

In Environmental Research and Pollution Control ...The pH of a river or lake is important in maintaining a proper ecological balance. The pH of the water directly affects the physiological functions and nutrient utilization by plant and animal life. Extremes in pH can reduce α lake to a lifeless, smelly bog.

Protecting our waterways requires constant monitoring of industrial effluent. Plating and metal finishing plants tend to produce acidic waste water, as do mining operations, Chemical plants often have very alkaline waste water. pH measurements are used as a guide to the proper neutralization of these plant wastes, as well as to monitor the final effluent quality. Occasionally, an acidic stream can be combined with an alkaline stream to produce a final stream which is close to neutral. pH measurements assure the proper management of this cost saving technique.

Industrial pH & ORP Probes

SH65C & SH65C-D series

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.


  • longer life, lower maintenance costs and higher accuracy
  • Up to 1000 meter transmission - built-in pre-amplifier standard
  • Replaceable salt bridge
  • Easy-In, Easy-Out model - adjustable insertion depth, eliminates cable twisting

The SH65 differential probe lasts long after others have failed.
Just change the reference solution or the salt bridge
and it's ready for another several years.


Measuring Range

  • pH 0 to 14.00 pH (Consult with us for applications below 2 and above 12)
  • ORP -1000 mV to +1000 mV or0 mV to +1000 mV, field selectable Flow Rate10 ft./sec maximum (3 metres/sec) Flow should be as low as possible in low conductivity water and in solutions with high suspended solids
  • Wetted Materials CPVC, ceramic, glass, titanium palladium alloy and EPDM (platinum for ORP probe)
  • Transmission  Dependant upon transmission distance and
  • Distance supply voltage


  • pH Less than 0.005 pH
  • ORP Less than 0.5 mV
  • Stability 0.03 pH per day, non-cumulative Response Time 1 second
  • Load at 20 mA 450 ohms
  • Output: 4-20 mA output is non-isolated and uncalibrated (SH65C)
  •             5-wire differential output (SH65C-D)
  • The instrument or PLC must provide 24VDC to power the sensor and be able to calibrate for offset and span.
  • Output Span 1.14 mA per pH / 16 mA per 1000 mV
  • Output offset 12 mA at 7.0 pH +/- 0.6 mA12 mA at 500 mV +/- 40 on 0 -1000 range12 mA at 0 mV +/- 40 on -1000 +/-1000 range
  • Pressure Limit  8 bar at 65°C maximum
  • Temperature Compensation Automatic: pH only -5 to 95°C (23 to 203°F) Temperature Limits
  • CPVC -5 to 95°C (23 to 203°F)
  • The temperature limit of probes in flow-through applications is limited by pressure and by the pipe fitting material.
  • Probe cable 2 conductor, twisted pair 4.6m (15ft) long


  • Process Control in areas with high electrical interference
  • Industrial and Municipal Waste Treatment and Neutralization

Suitable for:

  • Fume Scrubbers
  • Plating
  • Circuit Board Manufacturing
  • Food and  Beverage
  • Chemical Processing
  • Pulp & Paper
  • Mining
  • Power Generation
  • Pharmaceutical


0109-0001  SH65C pH electrode with 4-20mA output
0109-0002  SH65C-A pH probe with antimony electrode (used in hydrofloric acid) & 4-20mA output
0109-0003  SH65C-D pH electrode with 5-wire differential output
0109-0004  SH65C-D-A pH probe with antimony electrode & 5-wire differential output
0109-0005  SH65C-R ORP electrode with 4-20mA output
0109-0006  SH65C-R-G ORP probe with gold electrode & 4-20mA output
0109-0007  SH65C-R-D ORP probe electrode with 5-wire differential output
0109-0008  SH65C-R-D-G ORP probe with gold electrode & 5-wire differential output
0109-0009 SH65C-F flat face pH electrode with 4-20mA output
0109-0060  Submersion protector
0109-0061  Salt bridge (pack of 3)

SH60P/R-C-6 Variable Insertion, Differential pH/ORP Sensors

Now with larger electrode and ground rod for better signal-to-noise and faster response

  • 1.25" NPT CPVC compression fitting
  • Accurate differential measurement
  • Eliminates ground loop interference
  • Built-in pre-amp supports up to 3,000' sensor-to-analyzer distance
  • 15 ft. (5m) standard cable length
  • Replaceable saltbridge for extended service life
  • Flow-thru or submersible mounting
  • With temperature compensation device
  • Extended body option available for ball valve assembly (P/R60C-7)
  • 2 year warranty

This unique pH probe mounts in a standard 1 1/4” NPT tee, or in a tank, through a specially designed CPVC compression fitting. The probe enters straight into the fitting eliminating twisting of the cable; the pipe size is only 1 1/4” NPT and the insertion length is variable - between 7/8” and 5”.