Group A3 and B3 refrigerants shall not be used except where approved by the Authority Having Jurisdiction.
- Laboratories with more than 100 square feet (9.29 m2) of space per person.
- Industrial occupancies.
- Listed portable-unit systems containing not more than 0.331 pounds (0.150 kg) of Group A3 refrigerant, provided that the equipment is installed in accordance with the listing and the manufacturer's installation instructions. [ASHRAE 15:7.5.3]