General Safety Information
All industrial gases have properties which, if proper precautions are not followed, may cause injury, and possibly death. This article outlines the hazardous properties of the principal gases supplied by General Air Service, and describes the precautions and safety practices which must be followed to prevent accidents. It must be noted that it is impossible, in a article of this size to list every conceivable hazard which might occur. Therefore, the purpose of this article is to list the commonly recognized hazards, precautions, and recommended safety practices for a group of common industrial gases. If you, as the gas user, are faced with a safety hazard that you don't feel you can control or mitigate, or you simply have a question regarding a gas or its associated equipment, contact
General Air Service immediately.
In most instances, accidents are caused by improper application, misuse of the gas, or its container by inadequately trained personnel. Other major causes of accidents (in the use of industrial gases) are: 1) Improper installation. 2) Failure to provide proper and adequately maintained equipment. 3) Failing to follow the supplier's instructions in the operation of regulators and other compressed gas accessory equipment.
Proper training is essential. He or she must be able to recognize emergency conditions, knowing what action to take under such circumstances, while preventing exposure. A review of all label information and appropriate MSDS should be completed as a part of the training.
The following are general precautions that should be observed when handling any compressed gas.
- Never identify contents by container color, except in the case of medical gases.
- Color codes are not uniform throughout the compressed gas industry.
Cylinder contents must be identified by a decal, label, tag, or stenciling (all referred to herein as labeling). If an identifying label is lacking or not legible, return the container to the supplier, unused.
- Industrial gas containers are equipped with outlet connections that are in accordance with "Compressed Gas Association's" standard for "Compressed Gas Cylinder Valve Outlet and Inlet Connections." Such fittings are designed to prevent the connection of a gas container to a gas system with an incompatible gas. Never circumvent this protection by utilizing adapters.
- Never abuse gas cylinders by using them for rollers, blocks, striking arcs, etc.
- Never attempt to lift cylinders by the valve protection cap.
- Always move large cylinders with a hand-truck specially designed for transporting cylinders.
- Do not store or transport compressed gases in closed vans or automobiles.
- Always secure cylinders in transit or in storage to insure against their tipping over.
- Always use a pressure reducing regulator that is properly conditioned for the gas being used.
- Never attempt to transfill gas from one cylinder to another, or mix any gases in a cylinder.
- It is the responsibility of an employer to be certain that all employees using a gas are familiar with its specific properties and are properly trained for handling that gas.
State and local building and fire codes will apply to the installation and storage of compressed gases. The following information covers some of the major requirements for the storage of compressed gases.
Hazards of Industrial Gases
- Store all cylinders in designated areas that are secured.
- Flammable, toxic and Oxygen (or any Oxidizer) shall be separated from each other by a distance of at least 20 feet, or by an non-combustible barrier at least 5 feet high having a fire resistance rating of at least one-half hour. Inert gases (Argon, Nitrogen, Helium, Carbon Dioxide), since they are chemically inert and compatible with all other gases, may be used within the separation distance.
- Outdoor storage shall be kept clear of dry vegetation and combustible materials for a minimum distance of 15 feet.
- Cylinders stored outside shall not be placed on the ground (earth) or on surfaces where water can accumulate.
- Storage areas shall be provided with physical protection from vehicle damage.
- Do not store cylinders near elevators, truck loading platforms, gangways, or under operating cranes, or other areas where they can be damaged by falling objects.
- Cylinders shall not be exposed to temperatures in excess of 125F.
- Smoking and open flames shall not be permitted in Oxygen and flammable gas storage areas or within 20 feet of such areas.
- Observe local codes limits set for the storage of flammable gases in buildings
There are certain properties, hazards and precautions associated with the major industrial gases, as well as mixtures of same. These gases are: Acetylene, Air, Argon, Carbon Dioxide, Helium, Nitrogen, Nitrous Oxide, Oxygen, and Propane. Each of these gases has at least one of the following hazards:
NOTE: It should be stressed that more than one hazard can be associated with a particular gas.
Hazard 1: High Pressure
- High Pressure
- Extreme cold
- Asphyxiating (Inert)
Most cylinder gases are under high pressure. Although most high pressure cylinders are filled to pressures between 2000 psi and 3000 psi, cylinders with pressure ratings up to 7500 psi are commonly available. Even lower pressure gases, such as Propane can be hazardous if the proper equipment is not utilized, or if leaks are encountered.
Hazard 2: Extreme Cold
Some users of Argon, Carbon Dioxide, Helium, Hydrogen, Nitrogen, or Oxygen receive these gases in cryogenic liquid form. Both the liquid and its vapor are extremely cold, ranging in temperature from -109F to -452F.
The major hazards associated with these liquids are 1) danger of tissue destruction or severe frostbite 2) danger of asphyxiation and/or increased risk of fire hazard 3) build up of extremely high pressure from trapped evaporating liquids and 4) the embrittlement of many materials which may fracture at these temperatures.
Hazard 3: Asphyxiating (Inert)
Argon, Carbon Dioxide, Helium and Nitrogen are all inert gases. They will not support life and may cause asphyxiation by displacing the Oxygen in the air. To insure safety, the following precautions should always be observed:
Areas where any inert gas is used or stored must be kept well ventilated. None of the inert gases can be adequately detected by any human sense; yet all can be inhaled as readily as air. If the Oxygen content drops below 19.5%, the reactions of personnel exposed will depend upon the response of the individual involved. However, one should not expect to experience a choking sensation, rather, there may be an almost immediate loss of consciousness.
Before entering confined spaces which can be Oxygen deficient atmospheres, you should first check the Oxygen levels with an Oxygen analyzer. If there is the possibility of excessive Carbon Dioxide in a confined space, it is not sufficient to merely check the Oxygen concentration. Carbon Dioxide concentrations already in the blood stream, regulate certain bodily functions and excess concentrations may act as a depressant on the central nervous system.
Hazard 4: Oxidizing
Two industrial gases that are recognized as oxidizers are Oxygen and Nitrous Oxide. Materials which normally do not burn in air may burn with explosive violence in an Oxygen enriched atmosphere.
To insure safety, the following precautions must always be followed:
Hazard 5: Flammable
- Always refer to Oxygen by its name. NEVER call it "air" and NEVER use it as a substitute for compressed air.
- Keep all organic materials, especially oil, grease, wood, cloth, or asphalt, away from contact with Oxygen.
- Never attempt to lubricate any equipment used in Oxygen service. Arrange for repairs through your supplier.
- When liquid Oxygen is spilled or vented, a white cloud of condensed moisture results. Standing in or near this cloud will saturate clothing with Oxygen, making it extremely subject to rapid and intense burning. Should this happen, personnel involved should move to a clear area and avoid smoking, open flames, or other sources of ignition for at least one half hour to allow clothing to adequately air out.
- Prevent spillage onto asphalt or oil contaminated concrete, soil or other surfaces.
Acetylene, Hydrogen, and Propane are flammable gases. If any of these gases mix with air or Oxygen, the mixture is subject to ignition or explosion if exposed to an ignition source. The concentrations needed are low. 2.2% in air for Propane, 2.5% for Acetylene, and 4% for Hydrogen. In order to avoid accidents, observe the following safety precautions:
- Store cylinders containing flammable gases outdoors or in well ventilated areas. Away from oxidizers and never near sources of heat, flames, or sparks.
- Never use a flame to detect flammable gas leaks.
- Never permit the delivery pressure of Acetylene to exceed 15 psig.
- Never attempt to transfer Acetylene into another cylinder or mix any gas with Acetylene in a cylinder.
- Acetylene should not be exposed to copper, silver, mercury, their salts, compounds and alloys. Explosive acetylide compounds may be formed.
- Hydrogen gas burns with an almost invisible pale blue flame. If there is suspicion that Hydrogen is burning, approach with a broom extended into the suspected flame region to confirm the presence of burning. If the Hydrogen is burning, the broom will ignite. Call the fire department as soon as a fire is detected, unless the fire can be easily quenched by shutting off the source of the gas and the fire has not spread to adjacent areas or articles.
- Propane is much heavier than air, therefore, it will flow to low points, to be ignited at distances that may be quite far from the source of leakage