Closed dustproof pressure gauge and dustproof method thereof

The invention relates to the technical field of pressure gauges, in particular to a closed dustproof pressure gauge and a dustproof method thereof. A transparent cover is arranged on the shell, a sealing belt is arranged between the side face of the transparent cover and the shell, a gap exists between the shell and the transparent cover, a positioning cleaning mechanism is arranged on the shell and comprises a limiting ring, a water injection assembly is arranged on the limiting ring, and the water injection assembly is used for injecting liquid into the limiting ring. The fluid is guided outwards through the limiting ring, a pressing transmission assembly is arranged on the side face of the limiting ring, and the pressing transmission assembly is used for changing the length of the pressing transmission assembly through rotation of the limiting ring when the limiting ring rotates and cleaning dirt attached to the transparent cover and the gap along with rotation of the limiting ring. The size of the gap bet