DEKRA Process Safety

Safety with Flammable Liquids

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What are the hazards?

Flammable liquids can quickly convert to a high concentration of flammable vapors at ordinary temperatures. If this concentration is above the Lower Flammable Limit, ignition of the vapors can cause a flash fire – or an explosion if the combustion is confined. The temperature at which a LFL concentration can occur is the Flash Point of the liquid. Thus, if the Flash Point is below room temperature, a LFL concentration is likely to occur above a spill or pool [or around a spray or jet] of flammable liquid.

How can the hazards be avoided?

The most-important protection against flammable-liquid hazards is confinement of such liquids within equipment. Thus, maintenance of equipment to prevent leakage or rupture is essential. This includes periodic inspection and/or testing of equipment to detect impending failure. A philosophy that should be incorporated in a preventive-maintenance program is that inspections and tests need to be sufficiently frequent to ensure that the equipment will not fail during the entire interval between the inspections and tests.

What are the proper responses to a release of a flammable liquid?

It also is important that everyone who handles flammable liquids knows the hazards of fire and explosion. This is an OSHA “Hazard Communication” requirement, which states [in 29 CFR 1910.1200(b)(4)(iii)]: “Employers shall ensure that employees are provided with information and training to the extent necessary to protect them in the event of a spill or leak of a hazardous chemical.” The training should spell-out the proper response of operators, mechanics, and contractors to a spill of a flammable liquid. The response might be to leave the scene and call the Emergency Response Team, and to give the Team a description of the incident so that they can arrive well-prepared. For small spills, a response might be to cover the spill with dry chemical [as from an ABC fire extinguisher] or with sand or an oil absorbent. There may be other responses depending on Flash Points, the quantities of the liquids being handled, and the presence [or absence] of sprinkler protection. Thus, determining the proper response to flammable-liquid spills or releases should be a pro-active effort, and thus avoid a “reactive” response that might actually create hazards to employees. 

It is also important that members of an Emergency Response Team be protected against flash fire if responding to a release of flammable liquid. Thus, they should be wearing flame-resistant outer clothing in addition to protection for eyes, face, head, hands, and feet. Additional protection should be considered, such as the wearing of an aluminized and reflective flash suit and self-contained breathing apparatus, again depending on the severity of the hazard.

Richard W. Prugh 
Principal Process Safety Engineer 
DEKRA Process Safety