Gases are classified in different ways according to definitions by different regulations including Department of Transportation (DOT) and Fire Code regulations as well as by classification systems such as the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). These classifications are different and overlap in some ways. Users should be aware of all the hazards associated with the gases they are using. The links below are to the Fire Code definitions for compressed gases Web page and GHS and DOT definitions with pictograms to help identify how chemicals are classified.
- Compressed Gas and Cryogen Definitions (PDF)
- GHS-DOT Classification Comparisons Relevant to Compressed Gases (PDF)
Cylinder manufacturers include engraved markings on cylinders to allow proper identification of substances in the container. Do not attempt to identify the compressed gas in the cylinder on your own. Be sure to contact the manufacturer if you are unsure of cylinder contents.
Cylinders stored and used on campus must be clearly labeled. According to United States Department of Transportation (DOT) and Occupational Safety and Health Administration (OSHA) regulations, the labeling must list contents, concentrations, hazard classifications, safety precautions and the manufacturer or supplier. Do not remove manufacturer applied labels. Be sure to contact the manufacturer if you are unsure of a cylinder's contents.
All cylinders should bear a cylinder status tag stating one of the three conditions: full, in-service or empty.
Pressure regulators lower the gas pressure to a useable level. There are two kinds of pressure regulator designs, which appear similar: single-stage and two-stage.
- Single-stage regulators are used when precise control of delivery pressure is not required.
- Two-stage regulators give precise control.
Keep regulators clean and free of surface oil and grease, especially oxidizing gases.
Always use the proper regulator for the gas in the cylinder. Connection fittings, stamped Compressed Gas Association (CGA) numbers, plaques and/or decals on the regulator indicate for which gas the regulator is designed.
Do not use Teflon® tape, putty or other such materials on the threads unless specifically required (or applied) by the manufacturer or vendor.
Praxair, Inc. was selected for a University contract to provide compressed and liquid (cryogenic) gases after an open competitive solicitation process, and in consultation with several University departments.
Special Fire Department permits and engineering controls such as a gas storage cabinet may be required to use toxic or corrosive gases. Prior to ordering these gases, you are encouraged to contact EH&S at 206.543.7262 for an assessment and to ensure proper safeguards are met. Extra precautions must also be documented in your standard operating procedures (SOPs) for these chemicals.
Toxic and Highly Toxic Gases
ALL toxic and highly toxic gases are purchased through Praxair, unless unavailable.
Ordering information is provided on the UW eProcurement Web page.
Cylinders and Dewars are particularly vulnerable to damage during transport. Refer to the Transporting Compressed Gases and Cryogens Focus Sheet for best practices for transporting these materials safely.