J21K Series

Differential Pressure Switch

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

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


  • Rugged, NEMA 4X, epoxy coated enclosure
  • ​SPDT switch output
  • ​Welded 316 stainless steel or brass sensors
  • ​Unique isolated sensor design
  • ​Adjustable ranges:
    • 30 “Hg Vac to 90 psid
    • 1 bar Vac to 6,2 bar d
  • ​UL listed and cUL certified
  • ​Optional ATEX or GOST intrinsic safety compliance
  • ​Designed to meet Enclosure Type 4X
  • ​SPDT switch output
  • ​Adjustable deadband option for precise on-off control
  • ​Brass or welded stainless steel bellows sensors
  • ​External manual reset option


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