Section: Safety and Security
Policy Number: 7-24
Policy Name: Policy for Safe Use and Storage of Compressed Gas Cylinders
Date: May 5, 1982
Revisions: June 5, 1989; May 1, 1996; January 12, 2006


    To establish a policy on safe use and storage of compressed gas cylinders.


    To implement a safety policy on the use and storage of compressed gas cylinders so as to reduce the risk to students, staff, faculty, and the general public. To ensure the safe handling and storage of compressed gas cylinders at the University, the following rules shall be followed:

    1. General Use of Gas Cylinders

      This policy adopts as recommended practice all applicable National Fire Protection Association (NFPA) codes when this policy is applied to the design and construction of all new facilities where compressed gas cylinders will be used and stored.

      1. Know the contents of a cylinder and be familiar with the properties of that gas.

      2. Never use a cylinder that cannot be positively identified. Do not depend on color coding for gas identification.

      3. All cylinders must bear an identification tag stating the name of the gas or mixture and illustrating one of three conditions: full, in service, or empty.

      4. Handle cylinders carefully and fasten them in a secure manner at all times in an upright position.

      5. Transport larger cylinders only on a wheeled cart specifically designed for gas cylinders. This applies to all cylinders of size 2 or larger. Remove regulators and attach safety caps before transport.

      6. Never tamper with any part of a valve such as the safety or packing nuts.

      7. Do not strike an electric arc on cylinders.

      8. Use cylinders only with matched connectors and proper Compressed Gas Association regulator. Never install cylinder adaptors on a regulator. A regulator registration and periodic inspection program should be initiated by gas users.

      9. Leak test all connections to a cylinder with a soap solution. Caution: Any gas, regardless of its health hazard, may cause asphyxiation by displacing oxygen.

      10. Close cylinder valves when not in use, then bleed pressure from the regulator.

      11. Close valves on empty cylinders and mark "empty."

      12. Never attempt to refill a cylinder.

      13. Cylinders of compressed gases must be handled as high energy sources and therefore as potential explosives.

      14. When storing or moving a cylinder, have the cap in place to protect the valve stem.

      15. Do not expose cylinders to temperatures higher than 50o C. (122o F.).

      16. When classifying a gas mixture for use in the laboratory, base the classification on the most hazardous component.

      17. Never bleed a cylinder completely empty. Leave a slight pressure to keep contaminants out. Notify the vendor with a note if draw down occurs.

      18. Always wear safety glasses when handling and using compressed gases.

      19. Ground all cylinders containing flammable gases.

      20. When using gases with cryogenic properties, allow adequate ventilation and wear personal protection equipment including heavy gloves and safety goggles. (Gloves must be loose fitting to facilitate rapid removal in case of a spill.)

      21. The number of cylinders of flammable gases and oxygen is limited to a maximum of three per laboratory (refer to appendix).

      22. Cylinders which are not necessary for current operations shall be stored safely outside the laboratory.

      23. Cylinders of all gases having a health hazard rating of 3 or 4 and cylinders of gases having a health hazard rating of 2 with no physiological warning properties shall be kept in a continuously mechanically ventilated enclosure. There will be no more than three cylinders of these hazard ratings per hood or other continuously mechanically ventilated enclosure per laboratory (refer to appendix).

      24. When transporting cylinders on elevators, passengers should be prohibited until the cylinders have been unloaded at their destination. Signs should accompany the cylinder-in-transit warning passengers not to enter.

    2. Storage of Gas Cylinders

      1. Store cylinders in a ventilated area away from heat or ignition sources.

      2. Fasten cylinders securely at all times in an upright position.

      3. Cylinders in storage must be protected from weather extremes and direct sunlight. Protect the base of cylinders from dampness.

      4. Store flammable gases away from all other gases. This will be accomplished by a separation of at least 20 feet of open space or by a wall having a fire rating of at least one hour (refer to appendix).

      5. Safety caps shall be in place at all times during storage and transport of cylinders.

      6. Cylinders of all gases having a health hazard rating of 3 or 4 and cylinders of gases having a health hazard rating of 2 with no physiological warning properties shall be stored in a continuously mechanically ventilated enclosure if inside a building. If stored outside, the gases must be kept under lock and key and located away from populated areas and air intakes to buildings (refer to appendix).

      7. Cylinders will not be stored or left unattended in hallways, corridors, stairways, or other areas of access and/or egress.

      8. When classifying a gas mixture for storage, base the classification on the most hazardous component.

      9. Always separate empty and full cylinder storage.

    3. Transportation (excluding in building transport)

      1. Cylinders shall not be transported in a motor vehicle by University personnel on a routine basis. This transport should be handled by a licensed outside vendor.

      2. If transport by University personnel is absolutely necessary, contact the Department of Environmental Health and Safety at Extension 8475 for approval prior to transport.

Classification of Gases

Classification of compressed gases can become confusing depending on which of many codes is used. Consequently, this policy has adopted the National Fire Protection Association Classifications which gives three different hazards for each gas: namely, health, flammability, and reactivity. The hazards can be printed in symbol form as shown in the example of acetylene, or in tabular form as shown in Table No. 2.

(To see graphic chart, please see Policies and Procedures Manual)

It is the recommendation of the Office of Environmental Health and Safety that all personnel using, handling or storing compressed gases become familiar with this system.

The following tables qualitatively describe the numerical ratings of hazards and give examples of some gases.

Identification of Health Hazard Color Code: BLUE

Signal Type of Possible Injury
4 Materials which on very short exposure could cause death or major residual injury even though prompt medical treatment were given.
3 Materials which on short exposure could cause serious temporary or residual injury even though prompt medical treatment were given.
2 Materials which on intense or continued exposure could cause temporary incapacitation or possible residual injury unless prompt medical treatment is given.
1 Materials which on exposure would cause irritation but only minor residual injury even if no treatment is given.
0 Materials which on exposure under fire conditions would offer no hazard beyond that ordinary combustible materials.

Identification of Flammability Color Code: RED

Signal Susceptibility of Materials to Burning
4 Materials which will rapidly or completely vaporize at atmospheric pressure and normal ambient temperature, or which are readily dispersed in air and which will burn readily.
3 Liquids and solids that can be ignited under almost all ambient temperature conditions.
2 Materials that must be moderately heated or exposed to relatively high ambient temperatures before ignition can occur.
1 Materials that must be preheated before ignition can occur.
0 Materials that will not burn.

Identification of Reactivity (Stability) Color Code: YELLOW

Signal Susceptibility to Release of Energy
4 Materials which in themselves are readily capable of detonation or of explosive decomposition or reaction at normal temperatures and pressures.
3 Materials which in themselves are capable of detonation or explosive reaction but require a strong initiating source or which must be heated under confinement before initiation or which react explosively with water.
2 Materials which in themselves are normally unstable and readily undergo violent chemical change but do not detonate. Also, materials which may react violently with water or which may form potentially explosive mixtures with water.
1 Materials which in themselves are normally stable, but which can become unstable at elevated temperatures and pressures or which may react with water with some release of energy but not violently.
0 Materials which in themselves are normally stable, even under fire exposure conditions, and which are reactive with water.

Some Common Gases and Their Corresponding Hazard Ratings

Gases Health Flammability Reactivity Other+
Acetylene 1 4 3
Boron Trifluoride 3 0 1
Carbon Monoxide 2 4 0
Chlorine 3 0 0 OXY
Ethylene Oxide 2 4 3
Fluorine 4 0 3 -W-
Hydrogen 0 4 0
Hydrogen Sulfide 3 4 0
Methane 1 4 0
Nitrogen 0 - -
Phosgene 4 0 0
Propane 1 4 0

* This table is not intended to be a complete listing but only to serve as examples.

+ Other is supplementary information such as: Radioactive, acts like oxygen in supporting combustion, reacts violently with water.

If there is a question concerning the installation, storage, or classification of a gas, the user is referred to the references in the bibliography.

If these references are not available or if a question still remains, please call the Department of Environmental Health and Safety at extension 8475. Additional information regarding compressed gas safety can be found at Environmental Health and Safety web site.

Submitted by: Environmental Health and Safety