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OSHA Hazard Communication Letters of Interpretation
Storage and use of compressed gas cylinders; whether cylinder is considered an oxidizing compressed gas or oxygen cylinder.
- Issued
- Record type
- Interpretation
- Historical standard
- HCS 1994, pre-GHS archive
- Current standard
- HCS 2024, as amended
ILPI assessment: Cylinder principles remain; laboratory hazard definition has changed
This letter addresses the obsolete 1994 version of the Hazard Communication Standard (HCS). The HCS expressly covers simple asphyxiants and physical hazards. The letter’s old argument that the Laboratory Standard excludes methane because it lacks a listed health effect must not be used as current guidance: the modern laboratory definition expressly includes simple asphyxiants.
Use the current laboratory definitions, HCS laboratory provisions, compressed-gas requirements and oxidizing-gas classification. Compressed air still has pressure hazards even when not classified as oxidizing. The old GHS comparison and 2008 consensus-edition list are historical; do not assume a newer consensus edition automatically replaces an incorporated OSHA requirement. See de minimis for context.
Last reviewed: .
About this ILPI assessment
This comparison with current requirements is not a finding that OSHA has formally withdrawn this letter. This assessment reflects editorial judgment informed by human review and AI assistance. It is an opinion, may contain errors or omissions, and is not an official OSHA determination. For guidance on how OSHA requirements apply to your circumstances, contact your local OSHA office.
OSHA's notice about interpretation letters
The following notice is published on OSHA's interpretation pages; it is general guidance, not a letter-specific withdrawal notice.
OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.
Source: OSHA's original letter page.
May 23, 2008
Mr. Charles Tricomi
Consolidated Edison of New York
31-01 20th Ave. Bldg. 136 2nd Fl.
Astoria, NY 11105
Dear Mr. Tricomi:
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Thank you for your letter of September 18, 2007, to the Occupational Safety and Health Administration's (OSHA's) Directorate of Enforcement Programs (DEP). You had questions concerning standards applicable to the storage and use of compressed gas cylinders. Your paraphrased questions and our response follow.
Scenario: I have two compressed cylinders used for laboratory calibration of gas detectors. One cylinder contains 20.9% oxygen (balance nitrogen); the other contains 100% methane. The volume of each cylinder is approximately 2 cubic feet, and they are pressured at 2000 psi.
Question #1: What standards apply to the use, storage, and handling of these cylinders?
Response #1: The handling, use, and storage of compressed gas cylinders in applications other than welding and cutting in general industry workplaces is governed by OSHA's Compressed gases standard, 29 CFR 1910.101. The standard, at 29 CFR 1910.101(a), requires that gas cylinders be visually inspected to determine that they are in safe condition.1
The standard further states, in §1910.101(b), that "the in-plant handling, storage, and utilization of all compressed gases in cylinders...shall be in accordance with Compressed Gas Association (CGA) Pamphlet P-1-1965." We note that there are more recent versions of the industry consensus standards that are referenced in §1910.101.2 If the more recent consensus standards address hazards associated with compressed gases that are not addressed in the CGA pamphlets referenced in the standard, §1910.101, §1910.1200 [ILPI: Original HCS 1994 context · Current HCS], or any other applicable OSHA standard, the more recent consensus standards may provide support for a citation alleging a violation of the OSH Act's general duty clause, 29 USC 651(a)(1). If an employer is not in compliance with the requirements of an OSHA standard but is complying with the requirements of a current consensus standard that clearly provides equal or greater employee protection, the violation of OSHA's requirement will be treated as a de minimis violation. De minimis violations are those having no direct or immediate relationship to safety and health and result in no citation, penalty, or requirement to abate.
You stated in your letter that you are using these cylinders in a laboratory environment. OSHA's laboratory standard, §1910.1450, Occupational exposure to hazardous chemicals in laboratories, defines "hazardous chemical" as one that has been established to produce acute or chronic health effects in exposed employees. While methane is an asphyxiant, it does not produce the acute or chronic health effects described in 1910.1200 Appendix A [ILPI: Original HCS 1994 context · Current HCS; appendix content reorganized; see assessment] to which the lab standard refers. However, methane does present an explosion or flammability hazard. Therefore, OSHA's Hazard communication standard, §1910.1200 [ILPI: Original HCS 1994 context · Current HCS], would apply. The Hazard communication standard requires, among other things, that employees receive training with regard to the hazards [ILPI: Original HCS 1994 context · Current HCS] associated with the chemicals with which they work, how to detect the presence of those chemicals in the workplace, and the measures required to protect themselves from those hazards.
[ILPI note: At issuance: HCS 1994, pre-GHS archive. The laboratory definition has changed: current 1910.1450(b) expressly includes simple asphyxiants. Determine applicability from the current rule, not this historical exclusion rationale.]
Question #2: Is a cylinder that contains 20.9% oxygen (balance nitrogen) considered an oxygen cylinder or an oxidizing compressed gas?
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Response #2 The cylinder contains 20.9% oxygen and 79.1% nitrogen, which is essentially compressed air.3 While air is technically an oxidizer, compressed air presents no greater oxidation hazard than that of the atmospheric air already present in the workplace. This position was reflected in OSHA's comparison of its Hazard communication standard, 29 CFR 1910.1200 [ILPI: Original HCS 1994 context · Current HCS], with the Global Harmonization System (GHS) for the Classification and Labeling of Chemicals (available on OSHA's website at https://www.osha.gov/dsg/hazcom/GHSOSHAComparison.html). This document notes, in Section 2.4.2, that "[a]rtificial air containing up to 23.5% vol. oxygen % may be regarded as not oxidizing for some regulatory purposes (e.g. [sic] transport)." Therefore, the cylinder containing 20.9% oxygen would not be considered an oxygen cylinder or an oxidizing compressed gas for the purposes of 29 CFR 1910.101.
Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA requirements are set by statute, standards, and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.
Sincerely,
Richard E. Fairfax, Director
Directorate of Enforcement Programs
1 The standard, at §1910.101(a), requires the visual inspections to be conducted in accordance with the Hazardous Materials Regulations of the Department of Transportation (DOT) (49 CFR parts 171-179 and 14 CFR part 103), where appropriate. If these standards are not applicable, the standard requires that "visual and other inspections shall be conducted in accordance with Compressed Gas Association pamphlets C-6-1968 and C-8-1962..." [ back to text ]
2 CGA Pamphlets C-6-2007, Standards for Visual Inspection of Steel Compressed Gas Cylinders; C-8-2005, Standard for Requalification of DOT-3HT, CTC-3HT, and TC-3HTM Seamless Steel Cylinders; and P-1-2006, Safe Handling of Compressed Gases in Containers.[ back to text ]
3 CGA Specification G-7.1-2004, Commodity Specification for Air, indicates that compressed air is a blend of oxygen (ranging from 19% to 23%) and nitrogen (balance of the volume), and, in some cases, other trace gases.[ back to text ]
The original official public domain version of this document is available from OSHA at https://www.osha.gov/laws-regs/standardinterpretations/2008-05-23.