Clean Air Solvent(CAS) Certification Program

Rule 1171 (Solvent Cleaning Operation) and Rule 1122 (Solvent Degreasers) are two key components of the AQMD's ozone reduction strategy, as these rules control VOC emissions from numerous uses of solvents in industrial, commercial, and general purpose cleaning and degreasing activities. The rules were last amended in September 1996 (Rule 1171) and July 1997 (Rule 1122) to lower the VOC content limits of solvents in several usage categories. Effective January 1999, Rule 1171 and Rule 1122 require cleaning materials used in repair and maintenance operations and cold cleaners, respectively, to contain no more than 50 grams of VOC per liter of cleaning solvent as applied. The most common and effective grams of VOC per liter of cleaning solvent as applied. The most common and effective cleaners that meet this criteria are water-=based or aqueous cleaners that contain little or no VOCs, although other options such as VOC exempt compounds and vapor degreasers are also available to the user.

The low VOC requirement of the rules and the availability of the new solvents generate a new class of solvent called Clean Air Solvent (CAS). In order to be qualified, the clean air solvent has to meet all of the following criteria:

  1. VOC concentration is no more than 50 grams of VOC per liter of material, as applied and not as supplied;
  2. Composite vapor pressure is no more than 5 mm Hg of VOC mat 20°C (68°F);
  3. Reactivity is not higher than toluene; and,
  4. Contains no compounds classified as Hazardous Air Pollutants (HAPs) by the federal Clean
  5. Air Act, ODCs, or Global Warming Compounds (GWCs).