Differential gauge of stainless steel structure: the instrument adopts double corrugated pipe structure, namely the two bellows installed respectively in the work word symmetry position on either side of the frame. Derrick work activity end and fixed end respectively, on both ends up and down by a spring leaf and intermediate links. Two bellows in parallel condition, and pipe connection to the high and low pressure casing connectors; Gear drive mechanism installed directly on the fixed bracket, and through the link to the support activities; Dial directly fixed in gear transmission mechanism. Stainless steel working principle of differential gauge: based on the sensing element adopted two have the same stiffness of the bellows, and so on in the same measure medium forced it to produce the same attention leg respectively, because of the spring piece wait for a moment the two sides do not produce immunity, so stand still in the original position, so gear transmission mechanism is not action, make the pointer still refers to zero. When the different pressure ( Generally high side is higher than the low voltage side) Corrugated pipe, the two force on the leg of inequality, generate the corresponding displacement, and drive gear transmission and amplification mechanism, by the pointer is displayed in the differential pressure between the two values.