The day has arrived! The 2024 IFC recognizes the new GHS for Flammable Gases by breaking down CAT 1 Flammable Gases into 1A and 1B Flammable Gases. it also uses the phrase “Burning Velocity” (BV) which are defined and quantified as…
High BV Category 1B flammable gas has a burning velocity greater than 3.9 in/s (10 cm/s).
Low BV Category 1B flammable gas has a burning velocity of 3.9 in/s (10 cm/s) or less.
Category 1A
A gas that meets either of the following:
1. Ignitable at 14.7 psia (101 kPa) when in a mixture of 13 percent or less by volume with air.
2. A flammable range at 14.7 psia (101 kPa) with air of not less than 12 percent, regardless of the lower limit, unless data shows compliance with Category 1B.
Category 1B
A gas that meets the flammability criteria for Category 1A, is not pyrophoric or chemically unstable, and meets one (1) or more of the following:
1. A lower flammability limit of more than 6 percent by volume of air.
2. A fundamental burning velocity of less than 3.9 inches/second (99 mm/s).
The limits specified shall be determined at 14.7 psi (101 kPa) of pressure and a temperature of 68°F (20°C) in accordance with ASTM E681.
Where not otherwise specified, the term “flammable gas” includes both Categories 1A and 1B.