Table 1. Gas Cylinder Color Code Chart
| No. | Gas Name | Chemical Formula | Cylinder Color | Lettering | Letter Color | Ring Color | |
| 1 | Acetylene | C2H2 | White | Acetylene – Keep away from open flame | Bright red | ||
| 2 | Hydrogen | H2 | Light green | Hydrogen | Bright red | P = 20, light yellow single ring | |
| P = 30, light yellow double ring | |||||||
| 3 | Oxygen | O2 | Light (thioindigo) blue | Oxygen | Black | P = 20, white single ring | |
| 4 | Nitrogen | N2 | Black | Nitrogen | Light yellow | P = 30, white double ring | |
| 5 | Air | Black | Air | White | |||
| 6 | Carbon Dioxide | CO2 | Aluminum white | Liquid Carbon Dioxide | Black | P = 20, black single ring | |
| 7 | Ammonia | NH3 | Light yellow | Liquid Ammonia | Black | ||
| 8 | Chlorine | Cl2 | Dark green | Liquid Chlorine | White | ||
| 9 | Fluorine | F2 | White | Fluorine | Black | ||
| 10 | Tetrafluoromethane | CF4 | Aluminum white | Freon-14 | Black | ||
| 11 | Methane | CH4 | Brown | Methane | White | P = 20, light yellow single ring | |
| P = 30, light yellow double ring | |||||||
| 12 | Natural Gas | Brown | Natural Gas | White | |||
| 13 | Ethane | C2H6 | Brown | Liquefied Ethane | White | P = 15, light yellow single ring | |
| P = 20, light yellow double ring | |||||||
| 14 | Propane | C3H8 | Brown | Liquefied Propane | White | ||
| 15 | Butane | C4H10 | Brown | Liquefied Butane | White | ||
| 16 | Liquefied Petroleum Gas (LPG) | Industrial use | Brown | Liquefied Petroleum Gas | White | ||
| Residential use | Silver gray | Liquefied Petroleum Gas | Bright red | ||||
| 17 | Ethylene | C2H4 | Brown | Liquefied Ethylene | Light yellow | P = 15, white single ring | |
| P = 20, white double ring | |||||||
| 18 | Argon | Ar | Silver gray | Argon | Dark green | P = 20, white single ring P = 30, white double ring | |
| 19 | Helium | He | Silver gray | Helium | Dark green | ||
| 20 | Neon | Ne | Silver gray | Neon | Dark green | ||
| 21 | Krypton | Kr | Silver gray | Krypton | Dark green | ||
| 22 | Carbon Monoxide | CO | Silver gray | Carbon Monoxide | Bright red | ||
Gas Cylinder Conditions:
(1) Used within the inspection period:
a. Seamless steel gas cylinders:
Cylinders for corrosive gases, diving cylinders, and cylinders in contact with seawater shall be inspected every 2 years. General purpose cylinders shall be inspected every 3 years. Inert gas cylinders shall be inspected every 5 years. Cylinders that have exceeded 30 years of service life shall be registered and scrapped without inspection.
b. Welded steel gas cylinders:
Cylinders for corrosive gases shall be inspected every 2 years. General purpose cylinders shall be inspected every 3 years. Corrosive gas cylinders shall be scrapped after 12 years.
c. Liquefied gas cylinders:
From the date of manufacture, the inspection period for the first three inspections is 4 years each, and the inspection period for the fourth inspection is 3 years. They shall be scrapped after 15 years.
d. Acetylene gas cylinders: Inspected every 3 years.
(2) The gas cylinder shall have no defects, mechanical damage, or severe corrosion. Corrosion spots should be less than 2mm × 200mm.
(3) The paint color, lettering, and ring markings on the gas cylinder surface shall comply with the regulations and shall have a gas cylinder warning label. (See Table 2-1-1 in the attached document)
(4) All safety accessories shall be complete and intact – Gas cylinder accessories include burst disks, safety valves, fusible alloy plugs, cylinder valves, cylinder caps, and shock-absorbing rings.
