The J21K Differential Pressure Switch utilizes 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), the mechanism operates a single snap-action electrical switch. Control set point may be adjusted by turning the internal adjustment hex screw
For set point adjustment and re-calibration, connect the “High” pressure port to a calibrated pressure source.
Set point adjustment is achieved by varying the gap between the mechanical actuator and the plunger on the electrical switch.
To raise the differential pressure setting, turn the 5/16" hex head screw left (clockwise).
To lower the differential pressure setting, turn the 5/16" hex head screw right (counter-clockwise).
Types with Optional Adjustable Deadband Switch (Option 1520)
J21K models with option code 1520 incorporate a snap switch with integral adjustment wheel. Turning this wheel raises or lowers the pressure rise set point. The fall set point remains constant.
To use the adjustable deadband switch:
- Determine set point and deadband values.
For example, a rising set point of 20 psid with a deadband value of 6 psid.
- Set the falling set point at desired deadband value (determined by subtracting the deadband value from the desired set point) using the standard adjustment screw as outlined above.
Using the example from step 1, 20 - 6 = 14, so you would set the fall set point at 14 psid. This is your constant.
- Set your deadband by turning the adjustment wheel left to raise or right to lower the set point.
Using the example from step 1, turn the wheel left or right until 20 psid is achieved. This is your set point.