I recently was helping a client with some questions regarding their CAT 1B Flammable Refrigerant Process and was surprised to see that the “new” MAQ for these refrigerants is 10,000 pounds. Add the footnote exceptions, and we could have 30,000 pounds of this flammable refrigerant in a single fire area, either in “storage” or in a “closed system.”
NOTE: these flammable gases are a PSM flammable gas and have a TQ of 10,000 pounds. But as I have been saying for 10 years, don’t be surprised when OSHA says that only Cat 1A are PSM flammable gases. They have already updated the HAZCOM standard by redefining flammable gas categories.
The footnotes d and e state:
d. Maximum allowable quantities shall be increased 100 percent in buildings equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.1. Where Note e applies, the increase for both notes shall be applied accumulatively.
e. Maximum allowable quantities shall be increased 100 percent where stored in approved storage cabinets, day boxes, gas cabinets, gas rooms, exhausted enclosures or in listed safety cans in accordance with Section 5003.9.10. Where Note d applies, the increase for both notes shall be applied accumulatively.
OSHA's Definition of a CAT 1B Flammable gas
Gases which meet the flammability criteria for Category 1A, but which are not pyrophoric, nor chemically unstable, and which have at least either:
(a) a lower flammability limit of more than 6% by volume in air; or
(b) a fundamental burning velocity of less than 10 cm/s.
IFC's definition of a CAT 1B Flammable
A gas that meets the flammability criteria for Category 1A, is not pyrophoric or chemically unstable, and meets one of more of the following:
2.1. A lower flammability limit of more than 6 percent by volume of air.
2.2. A fundamental burning velocity of less than 3.9 inches/second (99 mm/s).