Compressed Gas: Safety Requirements for Compressed Gas Use

Last updated September 2, 2009 9:16:20 AM PDT

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Follow these safety requirements for use of compressed gases according to hazard class.

Check Toxic and Hazardous Gas Classification to determine the hazard class of your material. Then follow the appropriate usage requirements indicated below. Some exemptions for small quantities and short-term usage apply.

Safety requirements for compressed gas use
Requirements	Class IV	Lab use exemption	Class III	Class II	Class I
Exhausted enclosures (gas cabinets or hoods)		X	C¹	X	X
Treatment to 1/2 IDLH at atmosphere		X	X	X	X
Leak check (of installed system)		X	X	X	X
Emergency response plan, team, and drills		X	X	X	X
Flow-limiting device or flow-restricting orifice		X	C¹	X	X
Use in sprinkled spaces		X	X	X	X
Documented annual maintenance			X	X	X
Compatible piping			X	X	X
Purge system			C¹	X	X
Detector system		X (class I)	C¹	C¹	X
Emergency alarms (and explanatory signs)		X (class I)	C¹	X	X
Welded, compatible piping				X	X
Local shut-off				X	X
Interlocks				X	X
Emergency power (alarm, detector, ventilation)		X (class I)		X	X
Monitored secondary containment					X
Auto shut-off (manual or detector triggered)				X	X
Emergency control station					X
Exhaust flow alarm		X (class I)			X

¹ C = These systems are conditional and will be determined by the EH&S Chemical Safety Officer, (858) 822-1579.

Exemptions

Requirements are relaxed for small quantities and short-term usage as follows:

Less than 340 standard cubic feet (SCF) of class II and class III materials used for less than 30 consecutive days require:
- Initial consultation with the EH&S Chemical Safety Officer, (858) 822-1579
- Basic gas safety, including an emergency response plan and drills
- No lecture bottles
- Flow-restricting orifice (FRO)
- Exhausted enclosure adequate to dilute full release to 1/2 IDLH
- Leak check procedures for receiving cylinders and for manifolds
- Use in a sprinkled space

Less than 20 SCF of class I materials used for less than 30 consecutive days require above items, plus:
- Gas and exhaust system flow-detector systems connected to alarm system
- Emergency power for detectors and alarms

Requirements above may be relaxed for quantities less than 2 pounds; no single cylinder more than 1 pound (1/4 pound for class I). Quantities over threshold levels raise the level of classification.

Contacts

Research employees, contact the EH&S Research Assistance Program specialist assigned to your building.
Non-research employees, contact an EH&S general safety specialist, (858) 534-7513.

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Compressed Gas Classification & Requirements

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