I. Classification by manufacturing method

According to the method of manufacture, cylinders can be divided into the following four categories.

(1) Welding gas cylinders

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

(2) Controlled gas cylinders

Controlled cylinders are seamless cylinders made of seamless steel tubes. The head at both ends of the tube is heated on a special machine tool by spinning or extrusion and other ways to close the forming.

(3) Punching and drawing gas cylinders

It is the ingot after heating the first stamping concave head, after drawing made into open bottle blank, and then in accordance with the method of controlling gas cylinders into the top head and interface pipe.

(4) Winding cylinders

The cylinder is composed of an inner cylinder made of aluminum and an alkali free glass fiber with a certain thickness wound outside the inner cylinder. The role of the aluminum inner cylinder is to ensure the tightness of the cylinder. The pressure strength of the cylinder depends on the glass fiber shell wall (epoxy phenolic resin, etc.) wound into one outside the inner cylinder. Shell fiber material is easy to "aging", so the service life is generally not as good as steel cylinders.

Two, according to the physical state of the media classification

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

(1) Permanent gas cylinders

Gases whose critical temperature is below -10℃ are called permanent gases, and cylinders containing permanent gases are called permanent gas cylinders. For example, gas cylinders containing oxygen, nitrogen, air, carbon monoxide, inert gases, etc. Its commonly used standard pressure series are 15 MPa, 20 MPa, 30 MPa.

(2) Liquefied gas cylinders

Gases with critical temperatures equal to or higher than -10℃, which are gaseous at room temperature and pressure and become liquid after pressure and cooling. In these gases, some have higher critical temperature (higher than 70℃), such as hydrogen sulfide, ammonia, propane, liquefied petroleum gas, etc., known as high critical temperature liquefied gas, also known as low pressure liquefied gas. These gases are stored in low-pressure liquefied gas cylinders. At ambient temperature, low pressure liquefied gas always exists in 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 operating temperature is 60℃, the saturated vapor pressure of all high critical temperature liquefied gases is below 5 MPa, so such gases can be filled by low-pressure cylinders. Its standard pressure series are 1.0mpa, 1.6mpa, 2.0mpa, 3.0mpa, 5.0mpa.

(3) Dissolved gas cylinders

This cylinder is specially designed for acetylene. Due to the unstable acetylene gas, especially under high pressure, it is easy to aggregate or decomposition of acetylene slight vibration after liquefaction will explode, so can't filling with compressed gas state, must put the acetylene dissolved in a solvent (acetone) is commonly used, and in the interior of the porous materials, such as calcium silicate porous material, etc.) as absorbent. The highest working pressure of the dissolved gas cylinder is generally not more than 3.0mpa, and its safety problems are special. For example, acetylene gas cylinder is sprayed out, which will cause static electricity in acetylene cylinder, resulting in combustion, explosion and increased consumption of acetone.