Fixation on Histology

Flashpoints and Types of Fires


Flashpoints and Types of FiresFire is very much in the news these days, as large portions of America’s West Coast are engulfed in devastating forest fires. Your lab may not be hosting any gender reveal parties, but there are plenty of threats within the laboratory that can cause a fire, and a fire safety plan should be included in your overall hazard safety plan for your laboratory.

The first thing to be aware of is the various types of fires, as the type of fire will determine the best way to extinguish it. For example, terrible cooks know that you should not attempt to put out a grease fire with water. If you have ever used a fire extinguisher you may have noticed a letter of the alphabet on it. Fire extinguishers use an alphabet code to signify the types of fires they are effective at extinguishing. You will often see combination extinguishers that are good for ABC fires; this is what will commonly be in your home or lab. See OSHA Standard 29 CFR1910.157 for more information on fire extinguisher requirements.

A. Ash, this include ordinary combustibles like wood, paper, and cloth.

B. Boil: Flammable liquids like grease, oil, paint or solvents

C. Current: Live electrical equipment

D. Combustible metal (sorry, no handy mnemonic device for this one)

K. Kitchen: Commercial cooking equipment

The most common type of fire for the laboratory is type B. This is where the lab substances commonly referred to as flammables come in. OSHA defines a flammable liquid as having a flashpoint below 37.8 degrees Celsius. Flashpoint refers to the lowest temperature at which a liquid gives off enough vapors to form an ignitable mixture with the air. The lower the flash point the more dangerous it is, making something with a flashpoint of -45 degrees C like ethyl ether more dangerous, fire wise, than something like xylene with a 25 degree C flashpoint. Another factor in fire risk is the upper and lower explosion levels; the minimum and maximum concentration of the substance needed to support combustion. The larger the margin between the upper and lower explosion levels, the more dangerous it can be.

Taking simple steps like making sure flammables in the lab are stored in a safety can, inside a flammables cabinet, separate from oxidizers and corrosives, can help reduce the likelihood of a fire starting. A flammables cabinet is something to keep in mind while designing a laboratory, as it may also influence where the sprinkler system is positioned. You also need an 18 inch clearance between the ceiling and any storage or items like boxes, so that the sprinkler can reach the hazard.

How many flammables you can store depends on the square footage of the room and they should not be stored near an exit or on the floor. If you are storing any flammables in the refrigerator, the fridge has to be explosion proof (think Indiana Jones in the Crystal Skull movie…. Just kidding!). Regular fridges have a device that makes them go on and off to regulate temperature. An explosion proof fridge has this device on the outside so that it doesn’t spark and ignite anything flammable inside.

Looking for more info on laboratory safety? Check out NSH’s new Qualification in Laboratory Safety Prep Course, a continuing education course covering topics included on the ASCP QLS Exam.