Flammable Liquid Storage in a Repair Garage
An automotive repair garage (about 600 m2, single storey, combustible construction) stores flammable liquids in a back room: about 400 L of gasoline in 20 L containers, 200 L of parts-washer solvent, and 100 L of paint thinners. The room has a wooden door, no sill, and a floor drain connected to the municipal storm sewer. Workers dispense fuel from containers into vehicle tanks inside the room. The garage is sprinklered. The owner wants to increase storage to 800 L of gasoline and asks whether the sprinkler system is enough. The building official is concerned about the room construction, the drain, and the dispensing operation.
1. Assess the storage room construction and the floor drain against the requirements for flammable and combustible liquid storage.
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Room construction. A room storing flammable liquids in these quantities must be separated from the rest of the building by a fire separation with a fire-resistance rating appropriate to the quantity and class of liquid, and the openings must be protected by self-closing, fire-rated doors. A wooden door with no rating is not acceptable. The room should have noncombustible construction, a liquid-tight floor, and a sill or curb to contain spills.
Floor drain. A drain connected to the municipal storm sewer is a serious deficiency: a spill would discharge flammable liquid into the storm system, creating a fire and environmental hazard. The drain must be eliminated, trapped, or connected to a contained collection system (e.g., an oil-water separator or a closed sump), and the room must be able to contain a spill without releasing it to the sewer.
Dispensing. Dispensing fuel from containers into vehicle tanks inside the room introduces ignition and spill risk. Dispensing should be done in a designated area with proper ventilation, bonding and grounding, and no ignition sources, or moved outdoors.
Sprinklers. Sprinklers do not cure deficiencies in room construction, drainage, or dispensing practice; they are a supplementary measure.
2. Can the owner increase gasoline storage to 800 L if the sprinkler system is upgraded? What governs the maximum quantity?
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The maximum quantity of flammable liquid permitted in a storage room is governed by the code's limits for the class of liquid, the construction and fire separation of the room, and whether the room is a dedicated storage area or part of the occupancy. Increasing the quantity to 800 L requires checking whether the room, as constructed, is permitted to hold that quantity for the class of liquid involved. Gasoline is a Class I flammable liquid, and quantities are tightly limited in unsprinklered or lightly protected spaces.
Upgrading the sprinkler system may allow a larger quantity only where the code explicitly permits it and where the room construction, containment, ventilation, and separation are also upgraded. The correct answer is not simply "more sprinklers"; the owner must upgrade the room to a compliant storage room: rated separation, rated self-closing door, liquid-tight floor with containment, proper drainage, ventilation, and grounding/bonding for dispensing. If the room cannot be upgraded, the quantity must be limited to what the existing construction permits. The building official should require a design that addresses all of these, not just the sprinkler.