Many flammable cabinets are designed to meet the government structural specifications. Manufactured cabinets that are listed by Underwriter Laboratories or Factory Mutual are designated by a fixed label, which must remain attached to the cabinet at all times. However, unlisted cabinets are also acceptable if they meet certain standards. The bottom, top, sides and door of metal cabinets must be made of two layers of No. 18 gauge iron, or a stronger material, that is separated by at least 1.5 inches of air, according to the OSHA website. Wood cabinets must be constructed with fire-resistant plywood that is at least 1 inch thick. The cabinet's floor must be able to hold at least 2 inches of liquid without leaking.
An individual storage cabinet may contain up to 60 gallons of Class I and Class II liquids and up to 120 gallons of Class III liquids. Flammable liquids are divided into these three classes based on their flash point, which is the temperature at which they become a potential fire hazard. Class I liquids have a flash point below 100 degrees. Class II liquids are hazardous between 100 and 140 degrees, while Class III chemicals have a flash point of over 140 degrees.
There are several precise rules governing the security of flammable cabinets, particularly those made from wooden material. All joints of a wooden cabinet must be rabbeted and held together by flathead wood screws, according to OSHA. If there is more than one door, there must be a rabbeted overlap of at least 1 inch. Metal cabinets must be secured with a three-point locking mechanism, and the door must be at least 2 inches from the cabinet's bottom.
All containers within flammable cabinets should be individually sealed. There can be no spills or chemical residue within the cabinet. OSHA allows a maximum of three individual flammable cabinets in one storage zone. Cabinets must be completely sealed if they do not vent to the outdoors. Cabinets should be positioned away from exits or other high-traffic areas.