Compressed Gases are used through out the laboratory for industrial and research use. Compressed Gas Association (CGA) Pamphlet P-1 is cited 29CFRPart1910.101(b) (OSHA) as requirements for the safe operation and use of compressed gases. New York State Fire Code also provides requirements for the safe storage and use of compressed gases. Compressed gases inherently pose pressure safety hazards as well as potential hazards from chemical exposure, oxygen deficiency hazards (ODH) if oxygen concentration can fall below 19.5% by volume. Cryogenic fluid system may also be considered compressed gases.

Definitions, classifications and controls requirements at BNL are found in in the following SBMS Subject Areas: Compressed Gas Cylinders and Related Systems; Oxygen Deficiency Hazards (ODH), System Classification and Controls, and Cryogenics Safety.

The following information is provided to help in the use of compressed gases:

Tracking and Labeling

Compress Gases are chemicals and are tracked by BNL's Chemical Management System (CMS).

Inert gases (including compressed air) and commonly used gases such as oxygen and propane are typically track by a static/revolving inventory system that identifies the gas, the location stored and the maximum allowed quantity authorized to be stored in that location. Most other hazardous gases are individually tracked by a bar coding system that can allow inventories to be recorded and assessed against regulatory requirements (such as the NYS Building Code). The CMS team attaches the bar code to the cylinder and to a holder that can be attached to the cylinder as shown below. The holder is used to contain bar code information and forms to transfer the chemical (to another user or different location) or to delete the chemical (when emptied). Transfer and deletion can also be performed on-line through the CMS Web Transactions and Forms site.

Either way, a Cylinder Status tag needs to be attached to the cylinder that identifies if the cylinder is full (no contents have been withdrawn), in use (contents have been withdrawn and/or cylinder has been attached to either a distribution system or regulator), or empty (to be returned/disposed).

Example of Cylinder Tag for Static Inventory
 Example of Cylinder Tag for Non-Static Inventory

Compressed Gas Valve Connections

The Compressed Gas Association (CGA) has established standard valve outlet connections for gas cylinders. Standardized connections make a gas-tight seal and minimize the possibility of connecting a gas to a system not designed to handle that gas. The CGA connections listed in the table below are from CGA Pamphlet V-1 "Standard for Compressed Gas Cylinder Valve Outlet and Inlet Connections." They are for the more commonly used gases and do not include connections specified for gas mixtures. Vendors should be contacted for information on CGA connections for other gases and mixtures

There are several configurations of sizes, male/female orientations, left/right threads and mating surfaces. Regulators should be purchased for the gas to be used and will come with the proper CGA fitting to attach to the cylinder. These fittings should not be removed and changed from regulators. Do not use adapters. The mating surfaces of the majority of fittings are made to be leak tight without the use of aids such as Teflon tape. If leak tight connections cannot be made, then the outlet or attachment surfaces are damaged and should be removed from service.

Compressed Gas Cylinder Sizes

Compressed Gas cylinders are provided in standard sizes. The following is a listing of sizes with associated volumes and weight (in pounds of water):

Compressed Gas Safety Guidance

Compressed gases are classified into general safety categories such as: inert, flammable, oxidizer, corrosive, pyrophoric, toxic and highly toxic. Guidance and best practices relating to the storage and use of these gases can at BNL is provided in Working Safely with Compressed Gas Systems.

Air Products is an industry leader in the use of compressed gases and provide "Safetygrams" on various related topics.

Elevator Compressed Gas Cylinder Caution Posting is provided as an example when a compressed gas is moved in an Elevator.

Storage and Nesting

Compressed gases must stored, specifically from the hazard from having the cylinder valve protective cap sheared off. The amount of stored energy can cause the cylinder to become a projectile and as demonstrated on the Discovery Channel™ show "MythBuster's" can cause the cylinder to go through a concrete wall.  When not in used, the cylinder valve protective cap should be installed (some older cylinders do not have caps, it is recommended that these be returned to the supplier). Some gas suppliers provide cylinder valve protection caps that can be used while a pressure regulator is attached.

Cylinder Valve Protection Cap Regulator Installed Valve
Protection Cap

Insects can build nests inside caps, specially when stored outside. An approved method of control this problem is to install a pourous cover (such as a nylon "footee" (used in shoe stores) over the cap. The cap should only be installed hand tight. However, caps may become stuck on the cylinder. This issue is typical on cylinders stored outside. Only tools that do not enter the cap can be used to help remove the cap (such as a spanner wrench). The use of teflon tape is allowed on the cylinder threads to mitigate this problem.

NEVER use lubricants on the treads. They can contaminate the cylinder valve.

Foot Bootee Cap Cover Cap Wrench Teflon Tape Installation

Nesting depends on a three-point contact system such that all cylinders must be in contract at three points either with a secure wall or with another cylinder.   The following are examples of properly nesting compressed gas cylinders and storage in racks:

Note: A chain is required when in the storage rack to provide the third point of support and is recommended when nested.

Proper Securing of Cylinders

Compressed gas cylinders need to be properly secured when being stored or in use. Cylinder racks typically provide the required three (3) point of contact when being stored. When in use, cylinders need to be secured. Appropriate means of securing include manufactured clamps that are installed on vertical surfaces such as walls or benchtops. If no vertical surfaces are available, then floor stands should be used.

Bench Top Clamps Floor Stand Examples

Transport carts do not provide as safe as securing method as clamps and stands. However, if the use is temporary in nature, then cylinders can be used on cylinder carts* provided the following:

  • The carts are stable four (4) wheeled, non-collapsible carts;
    • rear wheels should have a wheel-base equal or greater than the front wheels;
    • the cylinder is secure at or above the center of gravity (c.g.) or mid-point of the cylinder on the cart;
  • Unless in use and attended, the regulator must be removed and the cylinder valve protective cap must be installed;
    • Cylinders without valve protected caps can not be stored on cylinder carts.
  • The cart should be secured (such as locking or choking the wheels) if possible and be provision provided to protect the cylinder from accidental contact;
  • Cylinder location do not disrupt egress path ways;
  • Cylinder are not stored in work space areas of electrical panels.

* See the OSHA Standard Interpretation on allowed provisions for the use and stowage of Oxygen/Acetylene (Oxyacetylene) systems on carts.

Unacceptable for Storage
  • Securing Strap Broken
  • Narrow Back Wheels
  • Frame Bent
 Improper Stowage
  • No Cylinder Valve Protective Cap
  • Securing strap below cylinder c.g.

Acceptable Storage

  • Cylinder Valve Protection Cap Installed
  • Chain fasten above cylinder c.g.
  • Rear Wheelbase as wide or wider than front wheels
  • Located out of traffic area (first photo)

Oxygen Deficiency Hazard Analysis

Hazard Evaluation Tools provides tools for determining oxygen concentrations and ODH classifications using either cryogens or compressed gas that can be recorded in a data base maintained by Safety Engineering. Also a tool for Carbon Dioxide is available that will give potential CO2 exposure levels.

OSHA Standard Interpretations

Storage of Flammable gases with flammable materials is not allowed. This includes storing small gas cylinders, such as propane bottles in flammable cabinets. OSHA provided a Standard Interpretation on April 19, 1999 reinforcing this requirement.

Oxygen/Acetylene (Oxyacetylene) systems used for welding and torch work. OSHA provided a Standard Interpretation on May 8, 2005 on their use and storage.

Compressed Gas Regulators

To safely use compressed gases, pressure reducing regulators are used. The two (2) primary types are single stage and dual (2) stage regulators. Both are safe as long as they are used per the manufacture's recommendation. Single stage regulators use one reducing assembly. They can be used where high flows are needed however the output pressure is subject to changes in cylinder (input) pressure. 2-Stage regulators provide stable output pressures for a large range of input pressure. For more detail information see Fisher-Rosemount Technical Monograph 27, the "Fundamentals of Gas Pressure Regulation." To avoid catastrophic failure of regulators, pressure relief devices are installed. The chart gives VICTOR regulator models (typically used at the laboratory) along with there respective output pressure ranges and relief valve part numbers and relief settings. Note: Regulators internal pressure relief devices are designed to protect the regulator body from the source pressure and therefore represents the maximum pressure that the regulator can put out in any failure condition.

VICTOR Regulators
Model Pressure Range
(psi)		 Relief Valve
Part Number		 Relief Setting
VTS 450A 2-15 0600-0016 300 psi
VTS 450B 2-40 0600-0016 300 psi
VTS 450D 5-125 0600-0018 400 psi
VTS 450E 10-200 0600-0023 500 psi
VTS 452A 2-15 0600-0070 300 psi
VTS 452B 2-40 0600-0070 300 psi
VTS 452D 5-125 0600-0071 400 psi
VTS 452E 10-200 0600-0067 500 psi
VTS 452MD 5-125 0600-0071 400 psi
VTS 452ME 10-200 0600-0067 500 psi
VTS 453B 2-40 0600-0016 300 psi
VTS 453D 5-125 0600-0018 400 psi
VTS 453E 10-200 0600-0023 500 psi
VTS 460A 2-15 N/A N/A
VTS 461B 2-40 N/A N/A
VTS 461D 5-125 N/A N/A

Rating of Tubing and Hoses for Compressed Gases

Typically compressed gas uses tubing or hoses to supply the system. Pressure rating and material compatibility is essential for their safe use. The following information is provided for reference in the choice of tubing/hoses:

If the tubing/hose is purchased with connectors, the user should ensure that it is stamped with it's pressure rating. The end fittings are installed by the user, than the fittings need to be secure using pressure rated clamps. Note that typical worm-type clamps (i.e. automobile radiator clamps) do not have a pressure rating (a typical automobile cooling system is only pressurized to 16 psig). Clamps should be used that do not damage the tube/hose and that permanently attaches to the fitting (will not come loose). If the tube/hose is does not have a manufacture's pressure rating (stamped), then a proof test (at 110% of operating pressure) need to be performed and documented.

Ear Clamp Type 1Ear Clamp Type 2 T-Bolt Clamp Type Band Clamp Type
Ear Clamp Type T-Bolt Clamp Type Band Clamp Type
Pipe Doping

It is important that if sealant are used on threaded connections (a.k.a. doping), that the material is compatible with the fluid (gas/liquid) used. Note, Sealant need to be used on all National Pipe Taper (NPT) threads and fitting. The most common forms of Pipe Dope are Pipe thread compounds and Polytetrafluoroethylene (PTFE) tape (commonly referred to as Teflon tape).

Pipe Tread Compounds

When selecting the pipe thread compounds, check the fine print very carefully to insure the product is listed as approved for the application you intend to use it for as some of these products have a very limited range of applications. White compounds are typically not compatible with flammable gases or oxygen. Specific applications include:

  • Potable water
  • Non-potable Water
  • Natural Gas
  • Propane
  • Fuel oils (#1 through heavy bunker oils)
  • Gasoline
  • High & Low pressure air
  • Low pressure steam
  • High pressure steam
  • Refrigerants
  • Electrical conduits

As the PTFE tape industry evolved into more products, they adopted a standardized color code (Always read the packaging to ensure compatibility).

  • WHITE -Single density: should only be used on NPT threads up to 3/8 inch.
  • YELLOW - Double Density: yellow double density is often labeled as "Gas type" (flammable gas)
  • RED - Triple Density: (Note-the container is red but the tape itself appears as a pale pink color). Presently required on all joints ½" diameter or greater.
  • GREEN - Oil Free PTFE tape: Required for use on all lines conveying oxygen (I.E. –medical oxygen or welding oxygen lines).
  • COPPER COLOR: contains granules of copper and is to be used as a thread lubricant but is not approved as a thread sealant. (Generally it is used as a thread lubricant on bolts or pipe threads for mechanical applications where no physical seal is required.)

PTFE tape is only approved as a thread seal when applied correctly. To apply you begin at the end of the pipe and wrap the tape under tension in the direction of the thread turns. Each successive layer should overlap the previous layer by ½ to 2/3 and continue wrapping until the entire threaded portion of the pipe is covered. (Minimum of 3 full turns).

Compressed Gas Lessons Learned

The following links are to lessons learned concerning compressed gas use, storage and transportation Lessons Learned:

Top of Page

Last Modified: June 4, 2012
Please forward all questions about this site to: SHSD Admin


DOE, Office of Science One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE's Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

Privacy and Security Notice  | Contact Web Services for help