J21K Series

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J21K Series

Differential Pressure Switches J21K Series

Differential Pressure Switches


The J21K Series Differential Pressure Switches utilize opposing metal bellows to detect pressure differences between two pressure sources. When the pressure at the high port exceeds the pressure at the low port by a pre-determined amount (set point), it activates the differential pressure switch with a single snap-action. These differential pressure switches are ideal for HVAC, industrial and building automation systems applications. To adjust the control set point, turn the internal hex screw.


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QtyModelDescriptionIn StockList PriceInternet Price
J21K-127 DIFF PRESS SW, ADJUST, 30 "HG VACUUM-0INFO1,507.00843.92
J21K-140 DIFF PRESS SW, ADJUST, 0-6 PSIDIn Stock1,200.00672.00
J21K-150 DIFF PRESS SW, ADJUST, 0-40 PSIDIn Stock1,223.00684.88
J21K-16020 DIFF PRESS SW, ADJUST, 1-15 PSIDINFO1,480.00828.80
J21K-16021 DIFF PRESS SW, ADJUST, 1-15 PSIDINFO2,295.001,285.20
J21K-232 DIFF PRESS SW, ADJUST, 0-25 PSIDIn Stock961.00538.16
J21K-254 DIFF PRESS SW, ADJUST, 0-90 PSIDIn Stock845.00473.20
J21K-357 DIFF PRESS SW, ADJUST, 0-70 PSIDIn Stock1,393.00780.08
J21K-S127B DIFF PRESS SW, ADJUST, 30 "HG VACUUM-0INFO2,544.001,424.64
J21K-S140B DIFF PRESS SW, ADJUST, 0-6 PSIDINFO2,544.001,424.64
J21K-S150B DIFF PRESS SW, ADJUST, 0-40 PSIDINFO2,544.001,424.64


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  • Adjustable setpoint
  • Sealed metal bellows
  • 15A switch rating
  • Epoxy coated enclosure

Relay Type : SPDT C-->N.O. @ setpoint Pressure rise

Relay Rating : 15 A resistive, 125/250/480 VAC

Setpoint : Internal Adjustment red 5/16th hex nut

Differential :

J21K-140: 0.1 to 0.4 psi (0.7 to 3 kPa)

J21K-150 : 0.3 to 0.7 psi (2 to 5 kPa)

J21K-232: 0.6 to 1 psi (4 to 7 kPa)

J21K-(254, 257): 2 to 4 psi (14 to 28 kPa)

Repeatability: ±1% over full range

Reset : Automatic reset by differential

Sensor Type :

J21K-1x0: Brass bellows diaphragm

J21K-2xx: Bronze bellows diaphragm

J21K-357: Stainless Steel bellows diaphragm

Operating Pressure Range :

J21K-140: 30″ Hg vac to 30 psi (1241 kPa)

J21K-150: 30″ Hg vac to 180 psi (1241 kPa)

J21K-232: 30″ Hg vac to 110 psi (759 kPa)

J21K-254: 30″ Hg vac to 200 psi (1379 kPa)

J21K-357: 30″ Hg vac to 350 psi (2413 kPa)

Overpressure: (Burst) 180 psid (1241 kPa)

Max Operating Pressure: (Proof)

J21K-140: 6 psid (41 kPa)

J21K-150: 40 psid (276 kPa)

J21K-232: 25 psid (172 kPa)

J21K-254: 90 psid (620 kPa)

J21K-357: 70 psid (483 kPa)

Operating Temperature: -40° to 160℉ (-40° to 71℃)

Operating Humidity: 10 to 90% Non-condensing

Wetted Parts: Brass, Bronze or SS bellows (See ordering)

Media Compatibility: Water, Glycol and Inert dry air

Process Connection: 1/4″ FNPT

Wiring Terminations: 3 Screw terminals (Com, NO, NC), 14 AWG max

Mounting: 2 tab holes 0.25″ dia

Enclosure Rating: Cast aluminum w/7/8″ conduit hole, NEMA 4X

Dimensions: 4.228″W x 8.0″H x 2.66″D, (10.7 x 20.5 x 6.8 cm)

Weight: 2.0 lb (0.9 Kg)

Approvals: UL File #E42272, CE

Warranty: 1 year


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