20V / 25V / A20V / A25V Series Vacuum Swichgage®
The 20 Series (2 inch/51 mm dial) and the 25 Series (2 1/2 inch/64 mm dial) Swichgage instruments are diaphragm-actuated, vacuum-indicating gages with built-in electrical switches. These switches are used for tripping alarms and/or shutdown devices.
Commonly used to measure loading of spark-ignition engines through intake manifold vacuum, the gages also can serve as overspeed protection from sudden loss of load on these engines. Use anywhere the vacuum source is compatible with port materials.