The commonly used gases in China are divided into four types: natural gas, liquefied gas, artificial coal gas, and a mixture of liquefied gas and air. Among them, natural gas has the least corrosiveness, followed by liquefied gas, and the most corrosiveness is artificial coal gas. The harmful substances in artificial coal gas are mainly sulfur dioxide, naphthalene, coal tar, etc.

There are no special requirements for the material of natural gas valves. If ordinary carbon steel is used, surface treatment must be done to prevent corrosion. However, do not use ordinary copper materials on valves for artificial gas. When it comes into contact with sulfur dioxide and water, it turns into copper sulfate, which causes significant corrosion to the parts. It should be noted that; Artificial gas is very prone to naphthalene formation on valves and pipelines, which is a white crystalline substance that is hard and difficult to remove, affecting the closing and opening of valves. Coal tar is sticky and difficult to clean everywhere in valves and pipelines. At present, there is no good way to solve it.

The valve body for artificial gas can be made of cast iron for low pressure, ductile iron for medium pressure, and cast stainless steel (316) for high pressure. Do not use ordinary cast steel. The rubber diaphragm chamber housing of the pneumatic control valve should not be made of steel plate stamping structure. If it is necessary to use it, a comparative surface treatment (such as nickel phosphorus chemical plating, etc.) should be done internally.