United Electric J21K-357 SPDT Differential Pressure Switch 0-70 PSID NEMA-4

The United Electric J21K-357 is a single-pole, double-throw (SPDT) differential pressure switch designed for use in HVAC systems, industrial applications, and building automation. This switch detects pressure differences between two connected sources by means of opposing metal bellows. The switch snaps on with a snap-action when the pressure at the assigned "high" port rises over the pressure at the "low" port by a predefined amount (setpoint). As a result, the electrical circuit is altered, enabling the switch to regulate different pieces of equipment in response to changes in pressure.The J21K-357 is perfect for severe situations because it is resistant to water, dust, and dirt because it is encased in a NEMA 4 shell. With its broad changeable setpoint range of 0-70 psi, it may be customized for a variety of uses.