1. Compressed gas - Any gas or mixture of gases in a container having a pressure exceeding 40 psia at 70ºF (21.1ºC), or regardless of the pressure at 70ºF (21.1ºC), having a pressure exceeding 104 psia at 130ºF (54.4ºC), or any liquid having an absolute vapor pressure exceeding 40 psia at 100ºF (37.8ºC).

2. Corrosive gas - A gas that when in contact with living tissue causes destruction of the tissue by chemical action. This term shall not refer to action on inanimate surfaces.

3. Cryogenic liquids - A cryogenic liquid is a liquid that has a boiling point colder than minus 150ºF (minus 65.5ºC) at 14.7 psia.

4. Cylinder - Generally a compressed gas container having a maximum water capacity of 1,000 lbs. (453.6 kg.). This is approximately the equivalent of 120 gallons (454.2 L).

5. Flammable gas - A gas is considered flammable when either a mixture of 13 percent or less (by volume) with air forms a flammable mixture or the flammable range with air is wider than 12 percent regardless of the lower limit. These limits shall be determined at atmospheric temperature and pressure.

6. Gas pressure - The force exerted by a gas on its surroundings. In the United States, gas pressure is commonly designated in pounds per square inch (psi). The term psia refers to absolute pressure. Absolute pressure is based on a zero reference point, the perfect vacuum.

7. Gauge pressure - The pressure above or below local atmospheric pressure. Therefore, absolute pressure minus local atmospheric pressure equals gauge pressure. Gauge pressure is commonly designated by the abbreviation psig.

8. Handling - Moving, connecting or disconnecting a compressed or liquefied gas container under normal conditions of use.

9. Highly toxic gas - A compressed gas that has a median lethal concentration (LC50) in air of 200 parts per million or less by volume of gas or vapor when administered by continuous inhalation for an hour (or less if death occurs within one hour) to albino rats weighing between 200 and 300 grams each.

10. Inert gas - A term used to describe a variety of gases which are chemically inactive.

11. Liquid cylinder - A pressurized double-walled and insulated container used to hold either cryogenic liquefied gas or refrigerated liquefied gas.

12. Manifold - A gas distribution system which transfers product through multiple outlets/inlets to compressed gas containers.

13. Material Safety Data Sheet (MSDS) - Written or printed material concerning a hazardous material prepared in accordance with the OSHA provisions of 29 CFR 1910.1200.

14. Pressure regulator - A pressure and/or temperature activated device used to prevent the pressure from rising above a predetermined maximum, thereby preventing rupture of a normally charged cylinder when subjected to a standard fire test.

15. Toxic gas - A compressed gas that has a median lethal concentration (LC 50) of more than 200 and less than 2,000 parts per million by volume of gas or vapor when administered by continuous inhalation for an hour (or less if death occurs within one hour) to albino rats weighing between 200 and 300 grams each.

16. Valve protection cap - A rigid removable cover provided for container valve protection during handling, transportation and storage.

1. Supervisors: Supervisors are responsible for ensuring that only trained staff handle or use compressed gas cylinders. The supervisor shall instruct his/her employees as to the contents of this policy and make frequent checks to ensure understanding and compliance. Supervisors shall immediately intervene in all instances involving unsafe acts or work practices. Supervisors must verify that compatible materials (valves, hoses, pipes, etc.) are used with compatible gases.

2. Users: Containers are generally provided by the gas manufacturer as a convenient device for storing and delivering a gaseous product to the user. The user is responsible for the safe use of the container and its contents and for returning the container to the gas manufacturer or distributor in the same safe condition as it was received. It is the responsibility of every employee to ensure that he/she abides by the rules and regulations set forth in this policy. The employee shall further ensure that the equipment is in proper working condition and report any discrepancies to the supervisor.

1. Before use all cylinders shall be inspected for damage (i.e., dents, gouges, evidence of leakage or cracks). If any damage is found, the cylinder shall be tagged "out of service" and returned to the manufacturer or distributor. Compressed gas cylinders must be hydrostatically tested every five years by the gas manufacturer or distributor. Check the cylinder upon arrival for the test date (usually stamped on the neck of the cylinder). Do not accept a cylinder if the most recent test date is more than five years old.

2. The user must know the contents of the cylinder. Do not use a cylinder if you cannot quickly determine its contents by wording on either the cylinder or a tag securely attached to the cylinder. If the tag has become detached or the label has been defaced, do not use the cylinder. Do not rely on color coding of the cylinder. Different manufacturers use different color codes and there is no standardized system of color coding.

3. Know the properties of the contents. Knowledge of the properties of cylinder contents is essential; be aware of the flammability, corrosiveness or oxidation potential as well as the physiological properties (i.e., toxic, anesthetic or irritating).

4. Handle all cylinders carefully. Careless handling may damage cylinders and valves. Install valve and dust covers when cylinders are not in use. Use cylinders for no purpose other than for containing compressed gases; handle them with the same care whether they are full or empty.

5. Secure all cylinders, whether in use or in storage, full or empty, by using a chain or other effective fastening device.

6. Move cylinders safely. Move cylinders from one location to another by hand-trucks. Secure the cylinder to the hand-truck while moving it. It is easy to lose control of a cylinder while sliding or rolling it.

7. Keep all cylinders in a vertical orientation at all times. Some gases/cylinders will pose problems if put in a horizontal position. If all cylinders are treated the same way these hazards can be avoided.

8. Do not tamper with cylinder valves or any part of a valve, such as a safety nut or stem-packing nut. If you are unfamiliar with the valves, please seek competent aid. When removing the safety nut instead of the outlet cap, for example, you will not be able to stop the flow of gas.

9. Use cylinders with appropriate equipment. Do not force connections or use unauthorized adapters. Never use a cylinder without a regulator.

10. Close cylinder valves. Always close the cylinder valve when the cylinder is not in use or when it is empty. Replace dust covers and dust caps.

11. Oxygen cylinders will support the rapid combustion of most materials. Flammable materials contaminated by oxygen, especially materials such as oil, paint or grease, become extremely dangerous. Oxygen is intended for use in welding. It is not intended for breathing and must not be substituted for air used in ventilation systems. Under no circumstances use oxygen as a substitute for compressed air or for any other unauthorized purpose. An explosion may result.

12. Never oil or grease a regulator. If oil or grease is found on an oxygen cylinder or regulator, it must be taken out of service immediately and the cylinder returned to the supplier.

13. Before attempting to place regulators or other fittings on a cylinder, be sure that the threads on the cylinder match those on the fittings. The type of thread, number of threads per inch and the hand of the thread must match to ensure a satisfactory seal. If the fittings are hard to turn, do not force them; instead, check the threads.

14. Open cylinder valves slowly so the gas will not be released suddenly into the regulators. If the valve is hard to open, keep the valve outlet pointed away from your body while you apply greater force. Operate valves fitted with handwheels only by hand. Do not use cheaters or pipes. Cylinders that do not have fixed handwheels will be equipped with keys, handles or nonadjustable wrenches on the valve stems during the time they are in service.

15. Before removing a regulator from a cylinder, close the control valves and allow the gas to escape from the regulator. Welders shall not leave an area with regulators or lines pressurized.

16. On oxygen cylinders, do not use a regulator that has been previously used for oil-pumped gases or any combustible gases. The gauges on oxygen regulators must be marked USE NO OIL.

17. Acetylene is a colorless, flammable gas with a distinctive garlic-like odor. A mixture of this gas with oxygen or air in a confined area will explode when brought in contact with a flame or other source of ignition. A pressure-reducing regulator must be used when drawing acetylene from a cylinder. Never adjust the regulator to obtain a delivery pressure greater than 15 psig.

18. Under certain conditions, acetylene readily forms explosive compounds with copper, silver and mercury. Contact should be avoided between acetylene and these metals, their salts, compounds and high-concentration alloys.

19. Only cylinders that are in use should be located in the lab or work area. Other cylinders should be stored in a designated storage area.

1. All cylinders, whether in use or in storage, empty or full, shall be secured by a chain or other effective fastening device preventing the cylinder from falling over.

2. Gases may represent a hazard because they are capable of being:

Some gases may combine several of the above hazards.

3. Do not store cylinders in locations where their temperatures may rise above 125ºF (51.7ºC) or near radiators or other sources of heat because high temperatures greatly increase the gas pressures in the cylinders. Many cylinders have fusible safety plugs that may release the contents when high temperatures or pressures exist in the cylinder. Do not store them where there is danger of accidental damage or in areas where they will be subjected to corrosive chemicals or similar damaging materials. Do not store cylinders of flammable gases near electrical wires, batteries or other conductors or sources of electricity. Empty cylinders must be plainly marked EMPTY and stored separately from full containers. Cylinders stored in the open must be adequately protected from extreme heat and cold. Cold weather usually increases the brittleness of the cylinder metal, and if brittle cylinders are handled roughly, they can rupture. Remove accumulated ice or snow to prevent cylinders from rusting. When gas cylinders are stored indoors, ventilate the area to prevent the accumulation of flammable or asphyxiating gases in the atmosphere. Cylinders shall not be kept in unventilated enclosures.

4. Cryogenic cylinders must be fitted with stainless steel plumbing only.

5. Cylinders when stored (either inside or outside) shall not obstruct exit routes or other areas.

6. All cylinders in storage shall have their valves closed. Valve protection caps are used on the cylinder and are designed to accept a cap. Caps shall always be in place and hand tight except when cylinders are in use or connected for use. All cylinders shall be stored valve end up.

7. Oxygen cylinders shall not be stored within 20 feet of highly combustible material (especially oil and grease), or within 20 feet of reserve stocks of acetylene or other fuel gas cylinders, or near any other substance likely to cause or accelerate fire. The only exception to this rule is when oxygen and acetylene are on a frequently used welding cart with regulator and hoses attached. If the cart is not used several times a week, the regulators must be removed and the cylinders must be properly stored.