The most basic knowledge about gases

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The following general knowledge about gases is provided for reference only. Those interested may provide additional information, especially regarding the gas safety aspect. 1 Types of high-pressure gas containers 1) Compressed gases: oxygen, hydrogen, nitrogen, helium, etc. 2) Dissolved gases: Acetylene (dissolved in propane, with activated carbon added). 3) Liquefied gas extraction: Carbon dioxide, nitric oxide, propane, liquefied petroleum gas. 4) Cryogenic liquefied gases: liquid oxygen, liquid nitrogen, liquid argon, etc. 2 Properties of high-pressure gases 1) Acetylene: colorless and odorless; (when impure, it has a garlic-like smell due to the presence of impurities such as H2S and PH3). Lighter than air, flammable, and explosive; contact with fire sources is prohibited, and it has an **effect on breathing. 2) Nitrous oxide (N2O): also known as laughing gas, it is colorless, has an aromatic sweet taste, is heavier than air, supports combustion, and has **sexual** properties. 3) Oxygen: colorless, odorless, slightly heavier than air; it supports combustion and breathing; oil must be avoided in valves and pipelines. 3 Containers for high-pressure gases and color coding: 1) For oxygen, hydrogen, argon, and nitrous oxide, cylinders are made of organic seamless steel. Acetylene and propane can be stored in cylinders made of ordinary welding steel. 2) All types of high-pressure vessels must be accompanied by a certificate, which shall be kept together with the vessel as part of the technical documentation. Regular inspections should be carried out (for example, once every three years); if there are issues by the date marked on the cylinder for inspection, it should be replaced promptly. The color codes for high-pressure gas cylinders in our country are as follows: Oxygen – sky blue; N2 – black; Argon – gray; Hydrogen – green; Chlorine – yellow; CO2 – gray; Acetylene – white. 4. Points to note when using high-pressure gases: 1) High-pressure gas containers should be stored outdoors, away from direct sunlight and exposure to wind and weather. 2) Acetylene pipes must not be made of red copper, as this will result in the formation of acetylene copper, which is merely an explosive. 3) High-pressure gases must be used equipped with a main regulator; the regulator, pressure gauge, and pipes must be dedicated and must not be used interchangeably. 4) In high-pressure gas regulators, the gas valve generally opens in a clockwise direction, while those of other types open in a counter-clockwise direction. 5) Do not fully open the valve when opening the cylinder; the acetylene cylinder should be turned no more than 1.5 turns to prevent propane from leaking out. 6) When the pressure of acetylene in the cylinder is below 0.5 MPa, it should be replaced; otherwise, propane in the cylinder will flow through the piping into the flame, causing the flame to become unstable and increasing noise, as well as leading to contamination and blockage of the acetylene piping.