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Rosemount™ 3900 General Purpose pH/ORP Sensor with Variopol (VP) Connection
The Rosemount 3900 pH/ORP combination sensor's double junction reference aids in the sensor's 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 sensor design makes the 3900 reliable in a wide range of aqueous solutions found in pipelines, open tanks or ponds.
Rosemount™ 3900 General Purpose pH/ORP Sensor with Variopol (VP) Connection


Operating Temperature
–10° to 100°C (14° to 212°F)
Pressure Port/Fitting
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
ORP: Platinum
Integral Cable: 32 ft (10m) cable with integral SMART preamp; 15 ft (4.7m) cable without preamp sensor
VP8 Cable: use 24281-XX, 2.5 ft (.8m) to 100 ft (31m)
Process Connection
Front facing: 3⁄4" and 1" MNPT; Rear facing: 1" MNPT


  • Extended 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
  • The 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
  • Variopol (VP8) cable connection option, for quick cable-to-sensor release, eliminates cable twisting
  • SMART enabled for pH measurements