Back To Top
Rosemount™ 3900 General Purpose pH/ORP Sensor
Rosemount 3900 pH/ORP Sensor
The Rosemount 3900 pH Sensor / ORP Sensor features a double junction reference that aids in the sensors' resistance to harsh environments and helps prolong sensor life.
The double junction protects the reference element from poisoning ions-such as ammonia, chlorine, cyanides, and sulfides. Both sensors are made with a porous Teflon® junction. The robust ph/ORP sensor design provides reliability in a wide range of aqueous solutions found in pipelines, open tanks or ponds.

How pH SensorsWork

Play Video
Rosemount™ 3900 General Purpose pH/ORP Sensor


Operating Temperature
–10° to 100°C (14° to 212°F)
Max. Operating Pressure
Maximum Pressure: 790 kPa [abs] (100 psig) at 100°C (212°F)
Materials of Construction
Stainless steel, glass, Teflon®, polyphenylene sulfide (PPS), EPDM and silicone (If selecting the ORP sensor, an additional wetted material is Platinum.)
Process Connection
Front facing: 3⁄4" and 1" MNPT; Rear facing: 1" MNPT


  • Extended pH sensor / ORP sensor life and protection against poisoning ions using a double junction reference
  • Enhanced performance and increased life with cracking resistant glass
  • Maximum chemical resistance provided by a rugged polyphenylene sulfide body
  • Operates in sub-zero temperatures down to -10°C (14°F)
  • Built-in solution ground for advanced diagnostics
  • pH/ORP sensor body features a one-piece construction with both front facing and rear facing process threads
  • ¾” and 1” MNPT process connections to meet a variety of application installation requirements
  • SMART enabled for pH measurements