The vapors of a flammable liquid often present the most serious hazard. The vapors can easily ignite or explode. Flammable liquid vapors are heavier than air and may settle in low spots, or move a significant distance from the liquid itself. If there is a long vapor trail, and one end gets lit through a spark or something, the fire can travel back along the trail to the source of the vapor, the liquid. This can be very dangerous.

The explosive concentration of vapors in air has a lower and upper limit. The lower explosive limit, or LEL, is the lowest concentration that will ignite. The upper explosive limit, or UEL, is the highest concentration that will ignite. If the vapor concentration is between the LEL and UEL, there is serious risk of fire or explosion. This is not, however, a fixed number. Sometimes the vapor will explode at a lower number, or at a higher number. It does not always follow the rules. For this reason, it is very important to remain cautious at all times when using a flammable liquid. Read these tips for storing your flammable liquids, so that you don't run into problems later on down the road.

Basic Principles for Storage, Dispensing and Use of Flammable Liquids.

Limit the quantities at any one location to those necessary, but not to exceed the limits specified below.

Prohibit smoking and eliminate other possible sources of ignition wherever flammable liquids are stored or used.

Prevent accumulation of vapors by careful handling and by providing adequate ventilation.

Use only approved containers, e.g. safety cans or metal drums, for all transportation and handling.

Avoid sparks from static charges generated by pouring; connect dispensing and receiving containers (if metal) by a suitable electrical conductor.

Provide fire barriers, fire alarms and fire extinguishers, as appropriate, at all locations of use and storage.

Label every container used for flammable liquids with the name of the material and the words: "Danger - Flammable - Keep away from heat, sparks, and open flames - Keep closed when not in use."

Fire Control:

Suitable fire control devices, such as 1-1/2" diameter hose or portable fire extinguisher, should be available at locations where flammable or combustible liquids are stored.

At least one portable fire extinguisher having an Underwriters' Laboratories Classification rating of not less than 20-B units should be located outside of the door opening into any room used for storage.

At least one portable fire extinguisher having an Underwriters' Laboratories Classification rating of not less than 20-B units should be located between 10 feet and 50 feet from any flammable liquid storage area located outside of a storage room but inside of a building.

Open flames and smoking should not be permitted in flammable or combustible liquid storage areas.

Materials which will react with water should not be stored in the same room with flammable or combustible liquids.