The earth’s atmosphere air contains 20.5% oxygen by volume.

Liquid oxygen has a purity of 99.5% minimum. On-site generators’ oxygen gas purity is typically from 90% to 99%

The outstanding properties of oxygen are its ability to sustain animal life and to support combustion.

Oxygen enriched atmospheres will greatly enhance combustion at concentrations as low as 24%, the combustion rate doubles and flame propagation is also increased. Many so called non-flammable textile materials will burn fiercely in an atmosphere containing as little as 30% oxygen.

Liquid oxygen will expand 860 fold increase in volume. In a closed vessel, this can result in a gas with a tremendous pressure increase.

SAFETY PRECAUTIONS

The National Fire Protection Association and U.S. Occupational Safety and Health Administration (OSHA) define oxygen as a Class 2.2 gas/liquid. The U.S. Department of Transportation (DOT) classifies it as a gas/liquid, UN 1072. CAS Registration 7782-44-7.

Health hazards

The inhalation of gaseous oxygen is used appropriately in many medical emergencies as well as long-term treatment. Such use should be with the advice of a physician. Inhalation of high concentration of oxygen for a few hours has not been found to produce harmful effects, except for some special classes of patients. When pure oxygen is breathed for 5 hours at sea level, for 3 hours at 3 atmospheres, 30 minutes at 4 atmospheres, or 5 minutes at 7 atmospheres, signs and symptoms of toxicity will appear. These include nausea, dizziness, bronchial irritation, hypothermia, increased depth of respiration, bradycardia, pulmonary discomfort or injury, peripheral vasoconstriction, amblyopia or loss of vision, syncope, epileptic seizures, and death.

Refer to supplier's Materials Safety Data Sheet (MSDS). In case of long term exposure to gaseous oxygen, remove to fresh air. Contact Emergency Medical Services (EMS) or a physician. In the event of contact with liquid oxygen, be aware of frostbite and take appropriate action.

Persons who have been exposed to an oxygen-rich atmosphere should not smoke or go near hot spots or sparks until they have changed clothing or properly ventilated their clothes in a normal atmosphere. A ventilation period of not less than 30 minutes, with movement of the arms and legs and with coats unbuttoned, is recommended.

Liquid oxygen is shipped at pressures below 1 380 kPa (200 psig) in heavily insulated small portable containers, tank cars, or tank trucks, again depending on the shipping method. Liquid oxygen is stored in specially designed tanks, commonly supplied by the oxygen supplier.

One gallon of liquid oxygen will expand to a gas with 860 fold increase in volume at atmospheric temperature and, if contained, can result in a gas with a tremendous pressure.

Never permit oil, grease, or other readily combustible substances to come in contact with oxygen cylinders, valves, regulators, gauges, and fittings.

Take special care to train maintenance and contractor personnel regarding oxygen hazards because many accidents take place during, or shortly after, maintenance turnarounds when piping and valves are subject to grease and oil exposure.

Storage systems for liquid oxygen are generally owned and maintained by an oxygen supplier. The site for the storage facility must be inspected by a supplier representative prior to selection and must correspond to NFPA 50. Storage vessels are doubled-walled and vacuum insulated with the inner tank made from alloys such as 9% nickel stainless steel.

Gas monitors should be provided to detect oxygen-rich atmospheres. Evacuate personnel if an enriched atmosphere alarm occurs to avoid saturation of clothing with oxygen.

Clothing will adsorb oxygen and remain saturated for up to one half-hour after leaving the exposure area. Oxygen saturated clothing may potentially ignite and burn extremely rapidly, even if only exposed to an ignition source such as a lighted cigarette.

Prohibit smoking in all areas where an oxygen-rich atmosphere can occur. Oxygen vigorously accelerates all combustion.

Design piping systems in accordance with CGA publication G-4.4 Industrial practices for Gaseous Oxygen Transmission and Distribution Piping Systems. Use the appropriate materials of construction, valve types, pressure relief devices, line sizes and pressure reducing valves to prevent potential combustion of the pipeline.

Take care to ensure that pipeline velocities are at acceptably low speeds, both in design and subsequently when oxygen usage increases. Pipelines should be designed to accommodate future growth.

Ensure that liquid oxygen can not be trapped between two valves without appropriate pressure relief valves. Trapped liquid oxygen will vaporize and build up sufficient pressure to rupture the pipeline.

Adequately clean oxygen equipment and systems, including piping, prior to the introduction of oxygen. Make reference to CGA publication G-4.1 Cleaning Equipment for Oxygen Service. Remove all combustible contaminants. Clean all parts prior to construction and completely clean the system after construction or subsequent maintenance.

Environmental and disposal

Since oxygen is present in the air, venting to the atmosphere poses no environmental risk. Take adequate precautions to ensure dissipation of the vented gases, so as to avoid the hazards associated with an oxygen enriched atmosphere.

Dispose of gaseous oxygen by venting in a manner that does not create an oxygen-rich atmosphere in a confined space. When disposing of liquid oxygen, be sure that the liquid and vapors do not come in contact with combustible materials, especially hydrocarbon materials such as oil or asphalt.

See attached.

Chemical Safety Information References

The best resource for information on oxygen and its safe handling is the Compressed Gas Association (CGA), National Fire Protection Association (NFPA), American Society for Testing of Materials (ASTM) or your oxygen supplier. In addition to reading and understanding your supplier's Material Safety Data Sheet, read and understand the following CGA, NFPA publications:

• CGA Handbook of Compressed Gases, Third Addition, pp. 526-535.
• G-4 Oxygen.
• G-4.1 Cleaning Equipment for Oxygen Service.
• G-4.4 Industrial practices for Gaseous Oxygen Transmission and Distribution Piping Systems.
• P-14 Accident Prevention in Oxygen-rich and Oxygen-deficient Atmospheres.
• P-1 Safe Handling of Compressed Gas in Containers.
• NFPA 50 Standard for Bulk Oxygen Systems at Consumer's Sites.
• ASTM G-88 Guide for Designing Systems for Oxygen Service.
• Compressed Gas Association, Inc.1725 Jefferson Davis Highway, Suite 1004, Arlington, VA 22202-4102