2024 IFC exemptions for CAT 1B flammable gases (those “mildly flammable” refrigerants

5003.8.3.5.4 Flammable gas.

The aggregate quantity of Category 1 B flammable gas having a burning velocity of 3.9 in/s (10 cm/s) or less stored and displayed within a single control area of a Group M occupancy, in an outdoor control area or stored in a single control area of a Group S occupancy is allowed to exceed the maximum allowable quantities per control area specified in Table 5003.1.1(1) without classifying the building or use as a Group H occupancy, provided that the materials are stored and displayed in accordance with Section 5003 .11.2.

5003.11.2 Category 1 B flammable gas with low burning velocity.

The aggregate quantity of Category 1 B flammable gas having a burning velocity of 3.9 in/s (10 cm/s) or less stored and displayed within a single control area of a Group M occupancy, in an outdoor control area or stored in a single control area of a Group S occupancy shall not exceed the amounts set forth in Table 5003 .11.2.

TABLE 5003.11.2

MAXIMUM ALLOWABLE QUANTITY OF LOW BURNING VELOCITY CATEGORY 1B FLAMMABLE GAS

IN GROUP M AND S OCCUPANCIES PER CONTROL AREA^a

 CATEGORY 1B

(Low BV)^d

For SI: 1 pound = 0.454 kg, 1 cubic foot= 0.028 m3.
a. Control areas shall be separated from each other by not less than a 1-hour fire barrier.

b. The building shall be equipped throughout with an approved automatic sprinkler system with a minimum sprinkler design density of Ordinary Hazard Group 2 in the area where flammable gases are stored or displayed.

c. Where storage areas exceed 50,000 square feet in area, the maximum allowable quantities area is allowed to be increased by 2 percent for each 1,000 square feet of area in excess of 50,000 square feet, up to not more than 100 percent of the table amounts. Separation of control areas is not required. The aggregate amount shall not exceed 80,000 pounds.

d. “Low BV” Category 1 B flammable gas has a burning velocity of 3.9 in/s (10 cm/s) or less.

5003.11.2.1 Fire protection and storage arrangements.

Fire protection and container storage arrangements for quantities of Category 1 B flammable gases permitted by Table 5003.11.2 shall be in accordance with the ALL of the following:

1. Storage of Category 1 B flammable gases on shelves shall NOT exceed 6 feet (1829 mm) in height, and shelving SHALL BE METAL.

2. Rack storage, pallet storage, or piles of Category 1 B flammable gas GREATER THAN 6 feet 6 inches (1981 mm) in height shall be provided with an automatic sprinkler system with a minimum design density of Extra Hazard Group 1.

3. Combustible commodities shall NOT be stored above Category 1 B flammable gases.

4. Flammable liquids shall be separated from Category 1 B flammable gases by a distance of not less than 20 feet (6096 mm). The separation is permitted to be reduced to 10 feet (3048 mm) where secondary containment or diking is provided to retain a flammable liquid spill at a distance of 10 feet (3048 mm) from the Category 1 B flammable gas storage.