J21K Series

Differential Pressure Switch

The J21K Series differential pressure switch monitors the difference between two system pressures or vacuums. It senses excessive flow deviation or verifies that a filter is clogged.

The J21K Series switch’s rugged design – with epoxy-coated enclosure and sealed metal bellows – lends itself to exacting applications. Widely found in refrigeration (chiller) and compressor applications, the J21K Series differential pressure switch is used for filter status monitoring and proof of flow.


  • Rugged, NEMA Type 4X, epoxy coated enclosure (with watertight conduit fitting)
  • ​SPDT switch output
  • ​Welded 316 stainless-steel or brass sensors
  • ​Unique isolated sensor design
  • ​Adjustable ranges:
    • 30 “Hg Vac to 90 psid
    • -1 bar to 6,2 bar
  • ​UL listed and cUL certified
  • ​Optional ATEX or EAC intrinsic-safety compliance
  • ​Adjustable deadband option for precise on-off control


Visit our Certifications Page for all J21K series Certifications

  • Designed to meet Enclosure Type 4X (with watertight conduit fitting)
  • ​UL listed and cUL certified
  • ​Optional ATEX and Rostechnadzor (GOST-R) intrinsic safety compliance
  • ​Optional adjustable deadband
  • ​Single switch output
  • ​Opposing bellows design

Installations Manuals

Ask an Expert

Ask An Expert

Please allow 24 hours to respond to your inquiry. For immediate assistance, contact us at 617-923-6977, M-F, 8-4:30 EST.

United Electric Controls will not send you unwanted email or provide your email address to third parties