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The D-pHi Series™

4-20 mA Differential pH Sensor

The D-phi Series re”D-phi”nes accuracy, reliability, and ease-of-use for pH sensors. 

Avoid headaches and wasted money with features that eliminate common installation and maintenance problems. This pH sensor has an extremely stable differential electrode that “D-phies” dilution and debris build-up. It also has a fast response time (96% accurate in less than 5 seconds) and cannot be poisoned by chemicals.  Lastly, the sensor is designed for 10+ years of service and the electrode never needs replacement. 

Order now to enjoy less maintenance and lower expenses for your business. 

Only $579 USD


Recommended for process control, wastewater, aquaculture, hydroponics, environmental remediation, and other applications requiring extremely stable, user-friendly, and low-maintenance pH monitoring.

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  • Refillable electrode that never needs replacement
  • Chemical-resistant titanium and Delrin® housing (PVDF available)
  • Built-in 0-50°C temperature sensor (secondary 4-20 mA output)
  • 3/4 or 1 NPT backend (depending on model)
  • Fully submersible to 100 psi and 150°F
  • Dry storage
  • Automatic Temperature Compensation (ATC)


The d-phi Series is fully submersible up to 100 psi

Model D-phi-s/i


Model D-phi-s has a 3/4″ NPT thread for standpipe mounting.

Model D-phi-s


Mount model D-phi-i inline up to 100psi with the built-in 1″ NPT thread.

Model D-phi-i

Additional Resources

pH Sensor Mounting Options

pH Sensor Inline and Standpipe Mounting Guide

pH Sensor

pH Range 0-14 pH
Output 4-20 mA | 2-wire
Electrode Type Differential
Wetted Materials Delrin®, titanium, glass, Viton™
Operational Temperature Range 32-155°F (0-70°C)
Thread Type 3/4 inch MNPT or 1 inch MNPT
Max Flow Rate 10 ft per second
Pressure Range 0-100 psi
Automatic Temperature Compensation 32-155°F (0-70°C)
Power Supply Voltage 8-40 VDC
Warm-up Time 2 seconds
Response time 96% < 5 seconds
Length 9.25 in (23.5 cm)
Width 1.00 in (2.54 cm) max.
Weight (No cable) 0.50 lbs (0.227 kg)
Linearity ±0.014 pH*
Accuracy ±0.014 pH*
Sensitivity ±0.01 pH

*After proper calibration


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

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.

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