Compressed Gas Safety for Laboratories

Discussion topics: Potential hazards Safety considerations regarding:

- Selecting/ Receiving gases

- Handling cylinders

- Storage

- Use Research apparatus/ systems Proper emergency procedures

Stanford UniversityEnvironmental Health & Safety

Occupational Health & Safety Program, x5-3209, lsteng@stanford.edu

Stanford Fire Marshal’s OfficeX3-0609, jleung@stanford.edu

Conmpressedgas.Rev.9-2000.pptIH Report#: 98-080 / SUFMO #02-00

Health & Safety Regulations- Compressed Gas Cylinders (CGCs)

Safety regulations (Cal/OSHA 8 CCR 4649-4650, California Fire Code Article 74 & 80) cover: Labeling & Construction of CGCs Safe handling of CGCs Safe use of CGCs Safe storage of CGSs

Cal/OSHA regulations online: http://www.dir.ca.gov/DIR/Title8/sb7g9.html

Characteristics of Gases

Gases are much lighter than liquids & solids.

The molecules of a gas are always in motion.

Escaped gases will eventually distribute themselves throughout the air in a room or other confined space.

Some gases have odors, some do not.

Most gases are invisible, some can be seen.

Non-liquefied Compressed Gases – Nitrogen, Argon, Helium, Oxygen, Hydrogen

Liquefied Compressed Gases-Chlorine, Hydrogen chloride, Carbon Dioxide, Nitrous Oxide

Compressed Gases in a Solution-Acetylene

Cryogenic Liquefied Gases-Nitrogen, Argon, Helium, Oxygen, Hydrogen

Types of Gases

Potential Hazards

High PressureAsphyxiationFlammabilityExplosion ToxicityCorrosionOxidationPyrophoricCryogenic

Purchasing/ Receiving Gases

REDUCE YOUR RISKS! Select least hazardous gases that will work Purchase only necessary quantities Select gases w/ returnable containers When receiving gas cylinders:

Check for leaks Visually inspect for damage Ensure valve cover and shipping cap is on Check for proper labeling

Cylinder Story

Cylinders come in different sizes, shapes and colors

Remember the gas supplier must label the cylinder with the contentsCheck the label before you accept, move or use the cylinder.

Name DOT Hazard Class

Safe Handling of CGCs

Before handling, ensure valve cap is

secured Transport CGCs using a suitable cart Never rely on valve cap as a handhold Always take the safest route for

transport

Do not leave un-restrained cylinders un-attended

Safe Storage of Compressed Gas Cylinders

CGC storage area requirements: Protected from:

• external heat sources • passing/ falling objects

Well-ventilated Isolation from highly flammable materials (>20 ft) Separation of incompatibles (check SU storage group information)

Restricted access to CGCs Away from main access/ egress points Avoid forming part of an electrical circuit with the CGC

(Safe storage- cont’d.)

Safe Storage of Compressed Gases

Attach valve cap when CGC is not in service CGCs shall be held in a suitable rack or

secured to other rigid structures Cylinders must be stored upright Metal restraints at 1/3 AND 2/3 height of cylinder Max of 2 CGCs per set of chains

Cylinder bench clamps are NOT allowed

Safe Use of Compressed Gases

DO NOT tamper with the stem and cylinder valves NEVER use damaged regulators, connectors, piping, etc. For cylinders in use, cylinder valves must have hand wheel

attached Close cylinder valve whenever:

work is finished cylinder is empty

Label empty cylinders Ensure safe & proper exhaust for purging & pressure relief for

toxic, flammable, or corrosive gases Never use cylinders as rollers or supports

Safe Use CGCs-- Special Precautions

Some gases require special permits and controls for operation. Toxic,corrosive, flammable and pyrophoric gases are examples. Check with your P.I., safety representative or SU EH&S before orderingany of these materials.

Research Apparatus/ Systems

CGCs shall be equipped with connections complying with ANSI B57.1-1965 / CGA (Cylinder Valve Outlet & Inlet Connections)

Label all gas lines Remember safety devices (check valves, flow restrictors) Pressure gauges Select proper construction materials Leak test system before start-up Ensure exhaust ventilation for the lab and apparatus is

on and working normally prior to opening CGC’s

Emergency Procedures

BE PREPARED! Know your emergency shutdown procedures Know your emergency contacts Know what to do “if” the unexpected happens

Guidance on standard and emergency procedures: SOP’s are not only good ideas they are required Laboratory supervisor or local safety coordinator SU Health & Safety Manual

For More Information Guide to Safe Handling of Compressed

Gases, Matheson Handbook of Compressed Gases,

Compressed Gas Association Gas Data Book, Matheson

Occupational Health & Safety Program- EH&S Ling Sue Teng, 725-3209, lsteng@stanford.eud

Stanford Fire Marshal’s Office- EH&S Joseph Leung, 723-0609, jleung@Stanford.EDU