... pressure as wall air flow indications , and other kind for the temperature , hydraulic systerm . 2) leak detection, vacuum pumps, air filter ... , etc. Low Pressure Gauge Specifications Diameter:50mm 2.5"(63mm) , 4"( ... 4" 3/8" 1/2" NPT Pressure instrument High pressure manometer Low pressure gauge aseismatic gauge Standless steel Gauges Contact Gauges ...