When measuring special media such as viscosity or acid base, diaphragm pressure gauges, stainless steel spring tubes, stainless steel movements, stainless steel housings, or bakelite housings should be selected. According to the different media tested, the pressure gauge should have a specified color code and indicate the name of the special media. The oxygen gauge must be marked with the words "No Oil" in red, the hydrogen should use a dark green lower horizontal line color code, and the ammonia should use a yellow lower horizontal line color code.

Pressure gauges are instruments that use elastic elements as sensitive elements to measure and indicate higher than ambient pressure. They are widely used in almost all industrial processes and scientific research fields. It can be seen everywhere in fields such as heating pipe networks, oil and gas transmission, water and gas supply systems, vehicle repair and maintenance plants and stores. Especially in the process of industrial process control and technical measurement, mechanical pressure gauges have been widely used due to their high mechanical strength and convenient production characteristics as elastic sensing elements.