Explosives
*Note 1: Identifies the new hazard class Desensitized Explosives (B.17).
*Note 2: Indicates that a chemical may still have explosive properties even though it is exempt from classification as an explosive. In these cases, these properties must be indicated on the SDS.
One commenter noted that the GHS made significant revisions to the classification investor database criteria for Explosive Hazard Classes in GHS Revision 9. While OSHA declined to adopt the classification criteria from the revision due to lack of notice, OSHA explained that there is already flexibility built into the labeling for explosives and in many cases following the GHS Revision 9 update, full compliance with the HCS will be achieved.
Flammable Gases
OSHA made significant changes to the Flammable Gas Hazard Class:
Two subcategories were added to this hazard class, pyrophoric gases, and unstable gases. The criteria indicated that if the gas is pyrophoric or unstable it is also considered a category 1A flammable gas.
A new subcategory 1B has been added Flammable gas. Category 1B flammable gases fall into category 1 but have a lower flammability limit or burning velocity.
Since OSHA added pyrophoric gases to the Flammable Gas Hazard Class, OSHA has removed pyrophoric gases as an independent hazard class.
Aerosols and Pressurized Chemicals
OSHA also made significant changes to the Aerosol Hazard Class (formerly known as Flammable Aerosols).
Non-flammable aerosols were added to this hazard class. OSHA found that many aerosols also fell under Gases Under Pressure. This resulted in an over-warning on aerosol cans, and could have weakened the warning on gas cylinders.
OSHA noted that pressurized chemicals were often the same chemicals in aerosols that posed similar hazards but were in refillable containers, which created a potential inconsistency in hazard warnings. In the revised Hazard Communication Standard final rule, OSHA adopted the designation Chemicals Under Pressure.
