The structure characteristics of the stainless steel pressure gauges with diaphragm case are summarized. It is used in boiler ventilation and gas piping to measure the micro pressure and negative pressure of various gas media in the process of high corrosion resistance. Stainless steel diaphragm pressure gauge for domestic users to the introduction of foreign advanced technology equipment in the same instrument to achieve the ideal supporting products. Structure principle: the instrument is composed of measuring system (including joint, corrugated film box, etc.), driving mechanism (including lever pulling mechanism, gear driving mechanism), indicating parts (including pointer and dial) and shell (including case, liner and glass). The working principle of the instrument is based on the corrugated film box under the action of the medium to be measured, the corresponding elastic deformation is generated, and then by the transmission of the gear drive mechanism and to enlarge, fixed in the gear shaft by the needle on the dial to indicate the measured value. The structure is equipped with overpressure protection device to prevent membrane box deformation due to overload, and zero adjustment device to facilitate the adjustment of zero.