Compressed Gas: Classification and Requirements
The following is UT Dallas’ requirements for safe storage and handling of compressed gases.
Definition
3.3.51.1 * Compressed Gas.
A material, or mixture of materials, that (1) is a gas at 68°F (20°C) or less at an absolute pressure of 14.7 psi (101.3 kPa) and (2) has a boiling point of 68°F (20°C) or less at an absolute pressure of 14.7 psi (101.3 kPa) and that is liquefied, non-liquefied, or in solution, except those gases that have no other health or physical hazard properties are not considered to be compressed gases until the pressure in the packaging exceeds an absolute pressure of 40.6 psi (280 kPa) at 68°F (20°C).
Requirement for Researchers
UT Dallas researchers working with compressed gases must follow an approved Standard Operating Procedure (SOP) and complete a Chemical Registration form via BioRAFT.
This SOP and Chemical Form must be pre-approved by the principal investigator prior to beginning any work with this material and by the UTD Chemical Hygiene Officer.
Information on this page is supplementary and is not intended to replace the approved SOP.
Hazard Classification
Use and storage of compressed gases is strictly regulated according to hazard classification. See the Toxic and Hazardous Gas Classifications Chart to identify the hazard class of a particular gas.
Compressed gases are classified as class 1, 2, 3 and 4, with 4 being the highest hazard. Classes are based on the lethal concentration to 50% of test animals (rats) of each gas (LC50).
UTD Compressed Gas Hazard Classifications
| Hazard Classification | Concentration |
|---|---|
| Class 1 | LC50 (rat) ≥ 5000 ppm |
| Class 2 | 3000 ppm ≤ LC50 (rat) ≤ 5000 ppm |
| Class 3 | 1000 ppm ≤ LC50 (rat) ≤ 3000 ppm |
| Class 4 | LC50 (rat) ≤ 1000 ppm |
Storage and Use
Storage and use requirements apply to all compressed gases.
Read Compressed Gas: Storage & Handling for detailed information.
Additional Precautions
Implement additional safety precautions for strong, particularly hazardous substances (Classes 2, 3, and 4). Requirements are relaxed for small quantities and short-term usage. For requirements on using lecture bottles, contact the UTD Chemical Hygiene Officer.
See the Hazard Class Requirements Matrix for detailed information on requirements and exemptions.
Purchasing
Follow the Chemical Hygiene Plan and Compressed Gas SOP at all times.
Complete your Compressed Gas and/or gas specific Standard Operating Procedure (SOP) in the Chemical Registration Form prior to ordering your material.
There are fire code restrictions on the quantities of some gases regarding use and/or storage within research buildings. Examples include:
- flammable (hydrogen, methane, acetylene)
- oxidizer (oxygen, nitrous oxide)
- highly toxic (arsine, phosphine, nitric oxide, nitrogen dioxide)
- toxic (ammonia, hydrogen sulfide, carbon monoxide)
- corrosive (hydrogen chloride, chlorine, hydrogen fluoride)
- unstable reactive (acetylene)
Order only what is needed for a reasonable amount of time.
Keep quantities to a minimum for all gases.
Reduce concentrations when possible.
Important: To ensure safe use and storage of Class 2, 3 and 4 gases, contact the UTD Chemical Hygiene Officer before ordering material.
Compressed Gas Safety Training for UT Dallas
All users of compressed gas must complete the BioRAFT module on Compressed Gas Safety. If you have additional questions about using and/or storing this material in your space, contact Risk and Safety at Safety@utdallas.edu.
Compressed Gas Alternatives
Gas cylinders are not always ideal in a lab setting for transportation, storage, safety or other practical reasons. Consider the alternatives below.
Gas Generation
Gas is generated on demand. This may alleviate fire code limitations on the storage and use of these gases:
- Oxygen
- Hydrogen
- Arsine
- Fluorine
- Methylsilane
- Ozone
References
UT Dallas requirements for engineering controls, protective equipment, storage, emergency response, warning systems and employee training are based on:
- NFPA 45: Standard on Fire Protection for Laboratories Using Chemicals
- NFPA 55: Compressed Gases and Cryogenic Fluids Code
- OSHA 1450: Occupational exposure to hazardous chemicals in laboratories
- OSHA 1910 Subpart Z: Toxic and Hazardous Substances
- UTD Chemical Hygiene Plan