29 CFR § 1910.123 - Dipping and coating operations: Coverage and definitions.
(a) Does this rule apply to me? (1) This rule (§§ 1910.123 through 1910.126) applies when you use a dip tank containing a liquid other than water. It applies when you use the liquid in the tank or its vapor to:
(i) Clean an object;
(ii) Coat an object;
(iii) Alter the surface of an object; or
(iv) Change the character of an object.
(2) This rule also applies to the draining or drying of an object you have dipped or coated.
(b) What operations are covered? Examples of covered operations are paint dipping, electroplating, pickling, quenching, tanning, degreasing, stripping, cleaning, roll coating, flow coating, and curtain coating.
Autoignition temperature means the minimum temperature required to cause self-sustained combustion, independent of any other source of heat.
Dip tank means a container holding a liquid other than water and that is used for dipping or coating. An object may be immersed (or partially immersed) in a dip tank or it may be suspended in a vapor coming from the tank.
Flammable liquid means any liquid having a flashpoint at or below 199.4 °F (93 °C).
Flashpoint means the minimum temperature at which a liquid gives off a vapor in sufficient concentration to ignite if tested in accordance with the test methods in Appendix B to § 1910.1200 - Physical Hazard Criteria.
Lower flammable limit (LFL) means the lowest concentration of a material that will propagate a flame. The LFL is usually expressed as a percent by volume of the material in air (or other oxidant).
Vapor area means any space containing a dip tank, including its drain boards, associated drying or conveying equipment, and any surrounding area where the vapor concentration exceeds 25% of the LFL of the liquid in the tank.