The 20DP and A20DP series (2 inch / 51 mm dial) and the 25DP and A25DP series (2 inch/64 mm dial) Swichgage models are diaphragm-actuated, differential pressure indicating gauges with a built-in electrical switch. The Swichgage indicates the pressure difference between 2 inlet ports, and provides a closing contact when the user-set limit is exceeded.

These gauges are intended to monitor for oil, fuel or water filter restriction: they can reduce the risk of dangerously high pressure which may rupture the filter, resulting in contaminants entering the system; they can also trigger automatic flushing (backwash) in irrigation systems. 

規格參數特點:
Monitors oil, fuel and water filters
Combination indicating gauge and user-set limit switch
Actuates alarm, shutdown or backwash when filter becomes clogged
Signals coolant loss or aeration on engine water pump
Metal case, ground return (20DP/25DP) or polycarbonate case, insulated return (A20DP/A25DP)
Available in dual (PSID/kPa) or single (Bar) scales
經典的繼電式儀表設計；
帶報警點輸出的壓力指示；
帶報警點可視并可從表面調節；報警點輸出可用于觸發報警及停機等功能；
產品技術指標超過通用的SAE標準。