Medical gas storage can be challenging, as there are many things to consider, such as type of gas, quantity, location, ventilation and exhaust. The relevant codes are the International Building Code (IBC), the 2021 International Fire Code (IFC) and the National Fire Protection Association’s NFPA 99, Health Care Facilities Code.
Oxidizing gases, such as oxygen and nitrous oxide, are limited by IBC/IFC to 1,500 cubic feet of gas at standard temperature and pressure. However, this can be doubled to 3,000 cubic feet in buildings with an approved automatic fire sprinkler system. In 3,000 cubic feet, a facility can hold about 12 H-Type oxygen cylinders. NFPA 99 allows up to 3,000 cubic feet to meet the less stringent requirements of Section 11.3, while quantities exceeding 3,000 cubic feet must meet the requirements of Section 220.127.116.11.2. Inert medical gases like nitrogen or carbon dioxide are not limited in quantity by IBC/IFC.
There are two allowable storage room configurations under IBC/IFC:
- The 1-hour exterior room must be separated from the rest of the building by approved fire barriers with a fire-resistance rating of not less than one hour. Any openings between the room and interior spaces need to be protected by self-closing smoke and draft control assemblies with at least a 1-hour rating. The room must have at least one exterior wall with two vent openings to the outside that are sized based on the quantity of gas stored, each with a minimum free area of 72 square inches. One opening must be located 6 inches from the ceiling and the other 6 inches from the floor.
- The 1-hour interior room has the same construction requirements as the exterior room, but this room must be exhausted to the exterior of the building by a 1-hour enclosed shaft duct system. Mechanical ventilation shall be supplied at a rate of 1 cubic foot per minute per square foot of room area.
Both rooms must have automatic sprinkler systems. Storage room construction requirements under NFPA 99 are a little less stringent but similar and no less important when ensuring medical gas storage compliance.
Sandy Renshaw PE, CCP, LEED AP, Principal mechanical engineer, Kaiser Permanente.