Portable Fire Extinguishers Are Required in Laboratories Using Chemicals

By Mark Conroy

The standard that applies to laboratory buildings, laboratory units, and laboratory work areas, where chemicals are handled or stored, is NFPA 45, Standard on Fire Protection for Laboratories Using Chemicals. The standard doesn’t apply to laboratory type facilities where small amounts of flammable liquids or gases are handled or stored and certain smaller facilities; although it could be used as guidance where portable fire extinguishers are being installed as a first line of defense for incipient fires.

The laboratories covered by the standard are classified based on the type and amount of flammable gases and flammable and combustible liquids. The classification of Class A, B, C, or D laboratory is determined based on a table in Chapter 10 of the standard, which provides limitations on quantities and doesn’t include the storage areas. In general terms, the largest amounts will be found in Class A laboratories and the least amounts in Class D laboratories. Typically, the laboratory class is determined by the authority having jurisdiction (AHJ) which could be the laboratory owner, their insurance company, or the local fire official.

Chapter 6 requires all laboratory units to be provided with fire protection appropriate to the fire hazard, and specifically includes portable fire extinguishers. This chapter also requires portable fire extinguishers to be selected and installed in accordance with NFPA 10.

Extinguishers for both Class A and Class B Hazards are needed in laboratories. For any area of a building there must be a complement of extinguishers for Class A Hazards complying with both area-of-coverage and travel distance criteria for Class A. Additionally, laboratories generally have Class B liquids stored in certain areas, including those in storage cabinets and safety cans, but the dispensing and handling of flammable and combustible liquids and gases is often conducted throughout the laboratory. Therefore, the actual walking distance (travel distance) from any point to the nearest fire extinguisher can’t exceed 30 or 50 ft, depending on the Class B rating of the extinguisher selected (see table below).

For the purpose of determining portable fire extinguisher size (rating), NFPA 45 requires that Class A laboratories be categorized as Extra Hazard and B, C, and D as Ordinary Hazard. The following table is used for selecting portable fire extinguishers where the Class B fire hazards comply with the Class A, B, C, and D laboratory classifications outlined in NFPA 45.

Many Class B, C, and D laboratories have safety cans and storage cabinets of flammable or combustible liquids. Portable fire extinguishers for extra hazard occupancy (40-B or 80-B) would typically be needed for those locations.

Keep in mind that all buildings (including laboratory buildings) need a complement of extinguishers for Class A, common combustible fires. Therefore, multi-purpose dry chemical or larger halogenated agent extinguishers are typically selected to satisfy both Class A and Class B hazard requirements for laboratories using chemicals.

The laboratory owner has a responsibility for life and property protection through prevention and control of fires and explosions involving the use of chemicals in the laboratory. The installation of portable fire extinguishers is not only required by NFPA 45 but is an important component of any laboratory owner’s fire and emergency management plan.