EQUIPMENT DIVISION 1340 SEABOARD INDUSTRIAL BLVD ATLANTA, GA 30301 PHONE: (404) 352-1680 FAX: (404) 350-6224 Regarding the Ozone Transport Commission Freeboard Requirement. Briefly, the Ozone Transport Commission is a group of 12 states and the District of Columbia forming the upper Middle Atlantic region through the Northeast. Congress passed legislation in 1990 creating the Commission for developing a unified approach to the growing ozone pollution problem in the Northeast. Since, the organization has been assembling a plan and issuing guidelines to control ozone and other emissions within the Commission states. One aspect of this control was the issuance of a guideline to the states that “cold solvent cleaners or degreasers” should have a freeboard ratio of 0.75. This requirement was “borrowed” from the Halogenated Solvent NESHAPS (National Emission Standards for Hazardous Air Pollutants). Due to the volatility of those solvents, the U.S. EPA designated the 0.75 freeboard standard to reduce air currents through the vapor zone of parts cleaners. The farther down the solvent is in the machine (greater freeboard ratio) the better that it can retain the vapors above the solvent layer. Freeboard is that portion of a tank’s or a tank-like enclosure’s capacity that is not used for holding a liquid. In the absence of an appropriate standard for less volatile hydrocarbon solvents, this ratio was adopted by the Commission and other states, most notably Texas. The freeboard ratio of a “cold solvent cleaner” or “cold solvent degreaser”, as parts washers are called by regulatory agencies, is determined by dividing the distance from the top of the solvent layer (solvent/air interface) to the top of the machine by the lesser of the two dimensions of the machine top-opening. The guideline for instituting a freeboard ratio for "cold solvent cleaners" is just that, a guideline. The states are free to adopt alternate regulations. Some have, such as Maryland and Pennsylvania, and use a volatility standard for the parts washer solvent to override the freeboard ratio requirement.