(1) The employer must make sure, if the tank has a condenser or a vapor-level thermostat, that it keeps the vapor level at least:

(a) Thirty-six inches (91 cm) below the top of the tank if the width of the tank is seventy-two inches or more;

(b) One-half the tank width below the top of the tank if the tank is less than seventy-two inches wide.

(2) The employer must make sure, if gas is used as a fuel to heat the tank liquid, that the combustion chamber is airtight (except for the flue opening) to prevent solvent vapors from entering the air-fuel mixture.

(3) The employer must make sure the exhaust flue:

(a) Is made of corrosion-resistant material;

(b) Extends to the outside;

(c) Has a draft diverter if mechanical exhaust is used.

(4) The employer must take special precautions to keep solvent vapors from mixing with the combustion air of the heater if chlorinated or fluorinated hydrocarbon solvents (for example, trichloroethylene or freon) are used in the dip tank.

(5) The employer must keep the temperature of the heating element low enough to keep a solvent or mixture from:

(a) Decomposing;

(b) Generating excessive vapor.