What is the color of gas

Identification and operation of the gas bottles
The color coding of the gas cylinders is standardized within the EU and Switzerland. The basis is the Euro standard DIN EN 1089-3. During the transition period until the end of 2006, a capital "N" was printed on the bottles (Neu, New, Nouveau) in order to avoid confusion with the old bottles. The color coding is only recommended for the bottle shoulder, the color of the bottle body is not mandatory. Even so, the gas industry has committed itself to up to three choices.

For didactic reasons, the original colors of the bottle bodies have been used in the graphic. Usually, however, gray or the color of the shoulder is used for the bottle body. In the case of gas cylinders for medical use, the cylinder body is generally white. This makes it easy to differentiate between industrial gases and medical gases, which are generally more pure. The dangerous goods label is the only binding marking of the bottle contents. This is based on the regulations of the GGVSE (Hazardous Goods Ordinance Road Railways). The graphic shows an example for labeling a bottle with technical oxygen.
Gas bottles with liquid gas or with LPG (Liquefied Petroluem Gas) are subject to a different standard. Liquid gas is usually a gas mixture with a high proportion of up to 95% propane and small proportions of butane, ethane, ethene or butane isomers. Propane cylinders are colored red, gray cylinders may also be used for camping purposes. They are also provided with an appropriate safety label. Some manufacturers such as Gebrüder Gloor AG in Burgdorf produce color-coded pressure reducing valves that match the shoulder colors of the gas bottles. This avoids mix-ups when connecting the valves.

(Photo courtesy of Gebr. Gloor AG)

When storing gas cylinders without a pressure reducing valve, the cylinder valve (1) generally closed. It must not be opened before the reducing valve is attached. It is put on with the help of a suitable wrench. When opening the cylinder valve (1) shows manometer a the existing tank pressure. By multiplying the cylinder pressure (for example 100 bar) by the cylinder space (for example 12 liters) you get the amount of gas available in liters (example: 100 × 12 = 1200 liters). With the pressure reducer (adjusting screw 2) the working pressure can be adjusted. In the school laboratory, this is usually between 0.5 and 1 bar. The working pressure is determined by the manometer b displayed. The gas is extracted by opening the shut-off valve (3). Silicone hoses are recommended, as rubber hoses are easily brittle. In addition, the hoses must be replaced at least once a year. For safety reasons, it is very important that the valves are closed again after the work is finished. First you turn the cylinder valve (1) tightly and then releases the remaining gas by opening the shut-off valve (3) from the pressure reducing valve. Then the adjusting screw for the working pressure (2) moved back again. The position of the adjusting screw must be checked again before each gas withdrawal.

Note: Schools have specific rules for storing, transporting and handling gas cylinders. In Germany these are regulated in RISU I-5. The following list gives an overview:
  • The pressurized gas cylinders are stored in a room or in a cabinet with permanent ventilation.
  • They must not be stored below ground level, in hallways or on escape routes.
  • When keeping a hydrogen cylinder with a pressure reducing valve attached, a protection area of ​​two meters must be observed. There must be no sources of ignition in this area.
  • All parts of the oxygen cylinder (valves, hoses, glass tubes) must be kept free of fats, oils or glycerine. Organic substances can self-ignite with pure oxygen.
  • Pressurized gas cylinders must be secured against falling over. The main risk is that the pressure reducer will be damaged.
  • Only one gas bottle of each type is kept ready.
  • Gas cylinders with toxic gases of categories 1 to 3 (e.g. sulfur dioxide, hydrogen sulfide) or with corrosive gases (chlorine, hydrogen chloride, ammonia) are not allowed in schools.
  • The delivery of replacement bottles is only carried out by transport companies. The return takes place only with the steel cap.
  • Valves, hoses or nozzles must be checked regularly for function and tightness. Hoses are exchanged at intervals.
  • Gas cylinders must never be stored with the valves open or under working pressure in the manometer.