1. Classification by manufacturing method

According to the manufacturing method, gas cylinders can be divided into the following four categories.

(1) Welding gas cylinders

The welded gas cylinder is composed of a cylindrical cylinder welded with a thin steel roll and a head welded at both ends. Welded gas cylinders are mostly used to contain low-pressure liquefied gases, such as liquefied sulfur dioxide.

(2) Control cylinders

Control cylinders are seamless cylinders made of seamless steel pipes. The heads at both ends of the pipe are heated and placed on a special machine tool through spinning or extrusion and other ways to close the forming.

(3) Drawing and drawing cylinders

It is to heat the ingot and first punch out the concave head, and then draw the open bottle blank, and then make the top head and interface pipe according to the method of gas cylinder.

(4) Winding gas cylinder

The cylinder is composed of an aluminum inner cylinder and an alkali-free glass fiber of a certain thickness wrapped around the outer of the inner cylinder. The role of the aluminum inner cylinder is to ensure the tightness of the gas cylinder. The pressure strength of the cylinder depends on the glass fiber shell wall wound into a whole outside the inner cylinder (using epoxy phenolic resin as a binder). The shell fiber material is easy to "age", so the service life is generally not as good as that of steel cylinders.

Second, according to the physical state of the loaded medium classification

Cylinders can be divided into the following three categories according to the physical state of the containing medium.

(1) Permanent gas cylinders

The gas with a critical temperature below -10 ° C is called a permanent gas, and the cylinder containing the permanent gas is called a permanent gas cylinder. For example, cylinders containing oxygen, nitrogen, air, carbon monoxide and inert gases are of this type. Its common standard pressure series is 15 MPa, 20 MPa, 30 MPa.

(2) Liquefied gas cylinders

A variety of gases with a critical temperature equal to or higher than -10 ° C, they are gaseous at room temperature and atmospheric pressure, and become liquid after pressure and cooling. Among these gases, some have a higher critical temperature (higher than 70 ° C), such as hydrogen sulfide, ammonia, propane, liquefied petroleum gas, etc., which is called a high critical temperature liquefied gas, also known as a low-pressure liquefied gas. The cylinders in which these gases are stored are low pressure liquefied gas cylinders. At ambient temperature, low-pressure liquefied gas is always in a state of gas-liquid two-phase coexistence, and the pressure of its gas phase is the saturated vapor pressure of the gas at the corresponding temperature. Considering that the maximum working temperature is 60 ° C, the saturated vapor pressure of all high critical temperature liquefied gases is below 5 MPa, so such gases can be filled with low-pressure cylinders. Its standard pressure series is 1.0MPa, 1.6MPa, 2.0MPa, 3.0MPa, 5.0MPa.

(3) Dissolved gas cylinders

This gas cylinder is specially used to contain acetylene. Because acetylene gas is extremely unstable, especially under high pressure, it is easy to polymerization or decomposition, the acetylene after liquefaction slightly vibration will cause an explosion, so it can not be filled with compressed gas state, must dissolve acetylene in the solvent (commonly used acetone), and filled with porous substances (such as calcium silicate porous substances, etc.) as an absorber. The maximum working pressure of the dissolved gas cylinder is generally not more than 3.0MPa, and its safety problems are special, such as acetone ejection in the acetylene cylinder, which will cause the acetylene cylinder with static electricity, resulting in combustion, explosion, increased acetone consumption and other hazards.