Full Features List

  • Combination double-junction electrode with large reference reservoir
  • Built-in 0-50°C temperature sensor (2nd channel)
  • Chemical-resistant Delrin®, PVDF, and 316 Stainless Steel housing (Titanium optional) 
  • True 2-wire sensor for simple installation
  • Solution ground
  • Narrow diameter (0.75 inches or 1.9 cm) 
  • Removable electrode guard
  • Fully submersible up to 70 psi 
  • Shielded, Kevlar®-reinforced, water-blocked polyurethane cable 
  • 4-20 mA signal capable of transmission up to 3 miles (with proper wire gauge)
  • Automatic Temperature Compensation (2% per degree Celsius)  
  • Reversible Input Protection and Operation  
  • 2-second warm-up time
  • Lowest power usage compared to other 4-20 mA pH sensors
  • Isolated to prevent ground loops  
  • Signal conditioning to remove background noise  

Low Maintenance

The weak point of pH sensors is their reference electrolyte, which gets diluted by the sample over time.  STs Series pH sensors mitigate this problem by incorporating a reference half cell with a large electrolyte reservoir.  In addition, the electrolyte is solidified into a gel and two Teflon™ junctions are used to further slow dilution.


pH Sensor

Output 4-20 mA
pH Range 0-14 pH
Operational Temperature Range 0-70°C
Electrode Type Silver/silver chloride, double junction, replaceable gel electrode
Transmitter Type 2-wire
Pressure Range 0-70 psi
Automatic Temperature Compensation 0-70°C
Isolation 600 VDC
Power Supply Voltage 8-40 VDC
Warm-up Time 2 seconds
Response time 95% < 5 seconds
Wetted Materials 316 Stainless Steel, Delrin®, Viton™, glass, epoxy
Length 14.25 in (36.20 cm)
Width 0.750 in (1.9 cm) maximum
Weight (No cable) 0.50 lbs (0.227 kg)
Linearity ±0.014 pH*
Accuracy ±0.014 pH*
Sensitivity ±0.01 pH
Stability ±0.03 pH per year
Repeatability ±0.01 pH

*After proper calibration

Temperature Sensor

Output 4-20 mA
Temperature Range 0-50°C
Accuracy +/- 1°C
Linearity +/- 0.5°C
Power Supply Voltage 7-40 VDC


Cable Material Polyurethane
Type 4 conductor, Kevlar® reinforced, water blocked, shielded, twisted-pair wiring
Maximum Distance 3 miles
Resistance per 1000 ft (304.8 m) 26 Ohms
Replaceable? Yes

pHionics products comply fully with all applicable EU Directives to bear the CE Mark.

Delrin® and Kevlar® are registered trademarks of DuPont™.

Viton™ is a trademark of Chemours.

Related Products

STs Series ORP Water Quality Sensor and Transmitter

STs Series Conductivity Sensor

STs Series Dissolved Oxygen Water Quality Sensor and Transmitter

STs Series Dissolved Oxygen Sensor

STs Series ORP Water Quality Sensor and Transmitter

STs Series ORP (redox) Sensor