HSNO Class 2
  Flammable Gases and Aerosols
     Flammable Gases - Class 2

• 2.1.1 Gases
   – category A & B
• 2.1.2 Aerosols
   – category A
• No tracking
                Class 2.1.1
• 2.1.1A - Flammable Gas high hazard
  – a gas or gas mixture which at 200C and at a
    pressure of 101.3kPa has a flammable range
    when mixed with air
  – Butane, Propane
• 2.1.1B - Flammable Gas medium hazard
  – Ammonia
             Class 2 Controls
•   Category A & B - high hazard flammability
•   Labelled with A or B
•   Flammable gases - no ignition sources
•   2.1A flammable gas shall only be opened or
    used in fume cupboards - gas bottles can be
    connected to equipment for use
        Class 2 - Other gases
• Gases which are not flammable or toxic are
  still compressed, and may have the potential
  to exclude air
  – e.g.: Argon
• Gases which are toxic, and in some cases
  also flammable
  – e.g.: carbon dioxide 6.4A (toxic)
  – Small cylinders of toxic gases should be kept in
    the fume cupboard
           Compressed Gas
• General principles - potential hazards
  – compressed state - rapid expansion and
    considerable force on release of gas
  – low temperature - many gases are at
    exceptionally low temperatures when released
    from containment
  – reactivity - gases which are normally highly
    reactive with certain substances tend to be
    much more so when released from compressed
    state (concentration).
          Compressed Gases
• Flammability - high concentration and
  pressure increases the potential hazard
• Toxicity - increase with increasing
  concentration in air
• Oxygen depletion - gas released may
  displace air, and cause asphyxiation, even
  though gas may not be toxic (helium, CO2
  and nitrogen) - consider use of detectors
 Compressed Gas - safe handling
• Cylinder valves inspected and kept clean -
  remove suspect cylinders
• All regulators checked before use. Leak
  test with detergent solution - not a match!
• ONLY use the tools provided for the
• Grease and oil to be kept away from
  connections and valves
 Compressed Gas - safe handling
• Do not drop or allow cylinders to fall on to
  the ground.
• All cylinders to be restrained - large G size
  should have two restraints - at the top and
  bottom third of the cylinder
• Fuel gases must be on a trolley for removal
  in case of an incident
• Flash back arrestors are required on
  flammable gas cylinders
 Compressed Gas - safe handling
• Open cylinder valves slowly to avoid
  shock-loading the diaphragm of the
• Acetylene should not come in contact with
  copper or any alloy containing 65% or
  greater of copper
• Empty cylinders should be stored outside

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