On average, we conduct around a dozen flammable liquid safety audits each year and I can not think of an audit where we were not asked about the ventilation requirements in 1910.106(e)(3)(v)(a) and/or NFPA 30, 17.11.1-10. Both of these standards require an area where a Class I Flammable Liquid is being transferred or dispensed be ventilated at a rate of not less than 1 cubic foot per minute per square foot of solid floor area or a fancy way of saying it… 1 ft3/min/ft2 or in metrics 0.3 m3/min/m2
So where did these number come from? They are based on an old “rule of thumb” that states areas where flammable liquids are handled and dispensed should be ventilated at a rate of at least six (6) air changes per hour. Most flammable vapors generated tend to go to the floor and stay at the ground level and because of this, flammable liquid areas are all about ventilating the floor area. With each square foot of floor area translating to 10 ft3 (3m3), six (6) air changes per hour equals 60 ft3 (19m3) per hour, or 1 cfm for that one square foot of floor area. At no time should we exceed 25% of the Lower Explosive Limit of the flammable materials! All ventilated air (e.g. dirty air) must be ventilated to a safe location outside the building. I suggest this location be cordoned off so that workers/visitors do not park/drive/walk through the area. I also suggest that signs be put up to notify personnel of what the cordoned off area if for. I have seen businesses actually designate smoking areas in these types of areas – NOT A GOOD IDEA!