United Electric J21K-16020 Differential Pressure Switch 1-15 PSI

The United Electric J21K-16020 1-15  is a differential pressure switch, which is an essential component in many  Heating, Ventilation, and Air Conditioning  systems. This keeps track of the pressure differential between two places in a system and, should the discrepancy go beyond a certain range, initiates an electrical response. The bellows, a flexible, airtight chamber that expands or contracts in response to pressure differential, determines how this switch works. The HVAC system receives an electrical signal from the bellows movement when the pressure differential exceeds a predetermined level, which triggers a switch mechanism. Depending on the particular application, this signal can then be used to modify airflow, turn on or off equipment, or set off alarms.