Industrial Maintenance and Construction/Support Services Safety Manual - Compressed Gas


Industrial Maintenance and Construction/Support Services Safety Manual - Compressed Gas


The use, storage and handling of all compressed gases in cylinders shall be done so in accordance with the provisions of the Compressed Gas Associations as set forth in Pamphlet P-1 “Safe Handling of Compressed Gases.”

General Guides For Use, Storage, and Handling of Cylinders

  1. All compressed gas cylinders must bear labels which clearly identify the contents.
  2. Installed piping systems for flammable gases, toxic gases, and oxygen must be in accordance with OSHA, NFPA, and ANSI standards and approved by UNC-CH Environment, Health and Safety.
  3. Compressed gas cylinders must be supported at all times. They may be supporting by the following methods:
    1. Wall mounted or bench-mounted gas cylinder brackets.
    2. Chains or belts that are anchored to a wall or bench.
    3. Free standing dollies or carts designed for gas cylinders and equipped with safety chains or belts.
  4. Individual cylinders or small groups of cylinders must be chained to a fixed object whether in use or in storage unless they are chained in a cylinder cart.
  5. Store cylinders in designated areas where they will not be knocked over or damaged by passing or falling objects. Where cylinders are stored in the open, they should be protected from accumulations of ice and snow and from the direct rays of the sun. Full cylinders should be used in rotation as received from the supplier.
  6. When an employee conducts a visual inspection and the cylinder is obviously damaged, it should be immediately returned to the supplier without the user attempting to use the compressed gas cylinder.
  7. Cylinders should not be subjected to a temperature above 125°F, nor should a flame ever be permitted to come in contact with any part of a compressed gas cylinder.
  8. Gas cylinders must have the valve protection cap in place except when in use. A cylinder connected to a piece of equipment and properly supported is “in use”. Remove the pressure regulators and replace the valve protection caps before moving cylinders, even if you have secured the cylinders to a dolly or a hand truck. (ex.: Do not transport acetylene and oxygen cylindrs, used for cutting and braxing with the regulators attached to the cylinders, except in the cylinder cart.)
  9. Do not drop cylinders or permit them to strike each other violently. Only cylinders approved for use in interstate commerce shall be used for the transportation of compressed gases.
  10. Cylinders must not be filled except by, or with the consent of the owner and then only in accordance with the regulations of the Interstate Commerce Commission.
  11. It is illegal to remove or change the numbers or marks stamped on cylinders.
  12. Do not use a lifting magnet or a sling (rope or chain) when handling cylinders. A crane may be used when a safe cradle or platform carrier is provided to hold the cylinder(s) securely in place.
  13. Do not use cylinders for rollers, supports, or for any purpose other than to carry gas.
  14. Make sure that the threads on regulators or other unions are the same as those on cylinder valve outlets (CGA Valve Connections System). Never force connections that do not fit.
  15. Regulators and pressure gauges provided for use with a particular gas must not be used on cylinders containing different gases.
  16. Open cylinder valves slowly. Never use wrenches or tools except for those that are provided or approved by the gas manufacturer.
  17. Oxygen must be stored at least 20 feet from fuel gases such as acetylene, HPG, propane, etc., or a fire-resistant partition must separate the classes of gases.
  18. Post all hydrogen and/or acetylene storage and usage locations with permanent placards that read: “Hydrogen/Acytelene – Flammable Gas – No Smoking – No Open Flames”.
  19. The wrench used for opening the cylinder valve should always be kept on the valve stem when the cylinder is in use.
  20. Caps are provided for valve protection. Such caps are to be kept on cylinders except when cylinder is in use.
  21. Do not tamper with the safety devices in valves or cylinders. Never attempt to repair or alter cylinder valves.
  22. Do not attempt to mix gases in cylinders. Close all cylinder valves when the cylinders are considered as being empty. This rule should be strictly enforced, including replacement of cylinder valve caps and marking or otherwise indicating that the cylinders are empty. Empty cylinders should be segregated from full cylinders and promptly returned to the supplier.
  23. Pressure regulators and gauges must be compatible with the cylinder valves (example: CGA Valve Connection System). The use of adapters, also known as “cheaters”, is prohibited.

Note: All oxygen valves, gauges, regulators, pipes, and fittings must be thoroughly free of oil, grease, graphite, or any other oxidixable substance. Such pipes, gauges, fittings, etc., must at no time be allowed to come to an elevated temperature due to proximity to welding operations, burners, or other heat sources.

Although oxygen is quite safe under normal temperature and pressures, elevated temperature and/or pressure or contamination may result in the rapid and violent oxidation of normally non-reactive materials. For example, a regulator used on oil-pumped nitrogen could produce a serious explosion if subsequently used for oxygen due to the oil residue.

Flammable Gases – Acetylene

  1. Cylinders containing flammable gases are not to be stored near highly flammable solvents, combustible waste material, and similar substances, or near unprotected electrical connections, gas flames, or other sources of ignition.
  2. Reserve stocks of cylinders containing flammable gases are not to be stored with cylinders containing oxygen. Within buildings, assorted oxygen and fuel cylinders shall be separated by a minimum of 20 feet or there must be a fire-resistant partition (wall) between the oxygen and fuel gas cylinders.

Toxic and Poison Gases

  1. Personnel handling and using poison gases shall have the following available for immediate use: Gas masks or self-contained breathing apparatus of a design approved by the U.S. Bureau of Mines for the particular service desired. Such equipment should be located convenient to the place of work, but shall be kept out of the area most likely to be contaminated.
  2. The Interstate Commerce Commission requires the poison gas label on cylinders containing the following materials:
    • Bromo-acetone
    • Cyanogen
    • Cyanogen Chloride (containing less than 0.9% water)
    • Diphosgene
    • Ethldichloroarsine
    • Hydrocyanic Acid
    • Lewisite
    • Methyldichloroarsine
    • Mustard Gas
    • Nitric Oxide
    • Nitrogen Perioxide (Nitrogen Tetroxide)
    • Phenlcarbylamine Chloride
    • Phosgene
  3. Persons using these or other poison gases are advised to seek and secure pertinent information for proper handling from the manufacturer.
  4. Toxic poisonous gases must be used only in fume hoods or gas cabinets vented directly outdoors. Appropriate first aid and antidote information supplies must be provided and clearly marked at room entrances.
  5. Piping systems for flammable gases, toxic gases, and oxygen must be approved by the Department of Environment, Health and Safety.
  6. Keep cylinders of all gases having a health hazard rating of three or four in hoods or other enclosures that vent directly outside. (ex.: ammonia, carbonyl sulfide, hydrogen cyanide, hydrogen sulfide, methylamine, nitric oxide, etc.) Each hood or enclosure shall not have more than three cylinders of this type. Also, clearly marked first aid equipment, antidote information, and supplies at room entrances shall be provided. Material Safety Data Sheets must also be made available.

Liquid Gases

Large vacuum insulated containers of pressurized liquid oxygen, nitrogen, argon, or helium must be transported, sorted, and used in an upright position. The extreme low temperature of the contents requires an upright position of the cylinders to permit venting of vapors periodically to maintain safe internal pressures. The instructions of the supplier with regard to handling and use of these cylinders should be followed.

Transportation and Handling


The handling and transportation of compressed gases will be in accordance with Department of Transportation regulations and recommendations published by the Compressed Gas Association which have been incorporated by reference in the Occupational Safety and Health Act.


  1. Gas cylinders must have the valve protection cover cylinder cap in place while being transported (inter- and intra-building transport).
  2. Motor vehicles used to haul compressed gas cylinders shall be equipped with racks or other means of securing the cylinders.
  3. Cylinders (or dewars) containing liquified hydrogen or toxic gases shall be transported in vehicles that are not enclosed.


  1. Vehicles must have the hand brakes set and precautions taken to prevent movement of the vehicle during loading and unloading of compressed gas cylinders.
  2. Smoking is prohibited during loading, unloading, and hand transportation of flammable gases.
  3. Dollies or specially designed hand trucks (equipped with safety straps or chains) shall be used for the transfer of compressed gas cylinders from loading area to shop or laboratory or other within-building transfers.
  4. Compressed gas cylinders must be securely supported at all times. Cylinders must not be left “free-standing” at any time, e.g., cylinders unloaded from a truck to a loading dock must be secured until placed on a hand truck for delivery within the building.
  5. Empty cylinders may contain appreciable residual gas and in any event are likely to cause injury if knocked over; therefore, empty cylinders shall be handled and transported in the same manner as charged (full) cylinders.
  6. Questions not answered in this section should be directed to the Department of Environment, Health and Safety.

Use and Storage


The use of compressed gases on the UNC-CH campus shall be in accordance with recommendations published by the Compressed Gas Association. The following rules summarize a few of the basic guidelines for the use and storage of compressed gases.

Types of Cylinders

There are two general types of compressed gas cylinders: Returnable (owned by the gas supplier, damage charged to the University), and non-returnable. Most suppliers will accept the return of their cylinders even if they are not empty (pressure approaching atmospheric). However, suppliers will not accept non-returnable cylinders under any circumstances. Disposal of non-returnable cylinders containing highly toxic or reactive gas can be very expensive. Therefore, purchase compressed gases in returnable cylinders if the option is available. If non-returnable cylinders are the only option, be prepared to use all of the gas or pay for the cost of disposing any leftover gas.

Support Required

Compressed gas cylinders must be supported at all times, whether full or empty. Acceptable methods of support include:

  1. Wall-mounted or bench-mounted gas cylinder brackets;
  2. Chains or belts anchored to walls or benches;
  3. Free standing dollies or carts designed for gas cylinders and equipped with safety chains or belts.

Valve Protective Covers

Gas cylinders must have the valve protection cover in place except when in use.

  1. A cylinder connected to a piece of equipment and properly supported is considered to be in use.
  2. The pressure regulators must be removed and valve protection covers replaced before moving cylinders even though the cylinders are secured to a dolly or hand truck (example: Acetylene and oxygen cylinders used for cutting, brazing, etc., may not be transported with the regulators attached to the cylinders).


Smoking is not permitted in the area where flammable gases are used or stored.


Gas cylinders must be used in an upright position and clamped securely at all times. Due to the extreme hazards created by using certain cylinders in a horizontal position (e.g., acetylene), approval must be obtained from the Department of Environment, Health and Safety.

Movement of Cylinders

Appropriate dollies or hand trucks must be used to move cylinders weighing more than 50 pounds. Movement by spinning, sliding, rolling, etc. is prohibited. For movement within shops and laboratories, cylinders weighing less than 50 pounds may be carried if desired.

NOTE: OSHA 1910.101

  1. “Inspection of compressed gas cylinders.” Each employer shall determine that compressed gas cylinders under his control are in a safe condition to the extent that this can be determined by visual inspection. Visual and other inspections shall be conducted as prescribed in the Hazardous Materials Regulations of the Department of Transportation (49 CFR parts 171-179 and 14 CFR part 103). Where those regulations are not applicable, visual and other inspections shall be conducted in accordance with Compressed Gas Association Pamphlets C-6-1968 and C-8-1962, which is incorporated by reference as specified in Sec. 1910.6.
  2. “Compressed gases.” The in-plant handling, storage, and utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or motor vehicle cargo tanks shall be in accordance with Compressed Gas Association Pamphlet P-1-1965, which is incorporated by reference as specified in Sec. 1910.6.
  3. “Safety relief devices for compressed gas containers.” Compressed gas cylinders, portable tanks, and cargo tanks shall have pressure relief devices installed and maintained in accordance with Compressed Gas Association Pamphlets S-1.1-1963 and 1965 addenda and S-1.2-1963, which is incorporated by reference as specified in Sec. 1910.6.

Contact Information

Policy Contact

Environment, Health and Safety
1120 Estes Drive
Campus Box #1650
Chapel Hill, NC 27599-1650
Phone: 919-962-5507


Article ID: 131984
Thu 4/8/21 9:21 PM
Mon 7/4/22 12:33 PM
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01/30/2019 8:14 AM
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01/30/2019 8:14 AM
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01/30/2019 8:14 AM
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03/01/2027 12:00 AM
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05/01/2014 12:00 AM
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Environment, Health and Safety