Many potential sources of spark, flame, or heat in laboratories can ignite flammable substances, such as open flames, static electricity, lighted matches and hot surfaces. When flammable materials are in use, pay close attention to all potential ignition sources in the vicinity. The vapors of flammable liquids are heavier than air, and can travel considerable distances. Recognize this possibility and take special note of ignition sources at a lower level than the level of flammable liquid use.

Flammable vapors from substantial sources such as spills can descend into stairwells and elevator shafts and ignite on a lower story. If the path of vapor is continuous, the flame can propagate itself from the point of ignition back to its source.

Properly bond and ground all metal lines and vessels dispensing flammable substances to discharge static electricity. When nonmetallic containers (especially plastic) are used, the bonding can be made to the liquid rather than to the container.