The 20V-30 Vacuum Swichgage is a 2" (51 mm) dual-scale dial, diaphragm-actuated vacuum-indicating gauge with a built-in electrical switch for tripping alarms and/or shutdown devices. This model has an adjustable range of 0-30 inches of Hg/kPa. The gauge mechanism is enclosed in a steel case coated to resist corrosion. It features a polycarbonate, break-resistant lens and a polished, stainless steel bezel to help protect this rugged, built-to-last instrument. The gauge pointer acts as a pressure indicator and as one switch pole which completes a circuit when it touches the adjustable limit contact. Contacts have a self-cleaning motion to ensure electrical continuity.
The 20V-30 Vacuum Swichgage is commonly used to measure loading of spark ignition engines through intake manifold vacuum. The gauge can serve as an overspeed protection from sudden loss of load on the engine and can be used anywhere the vacuum source is compatible with port materials. A pulsation dampener is included with each Vacuum Swichgage to help eliminate pointer flutter. The 20V-30 has a beryllium copper diaphragm, two adjustable limit SPST contacts (pilot-duty only, 2A @ 30 VAC/DC), and a 1/8-27 NPTM brass process connection.