|(a) Applicability. Any site with a cooling tower heat exchange system in the Houston/ Galveston/Brazoria area, as defined in §115.10 of this title (relating to Definitions), that emits or has the potential to emit a highly-reactive volatile organic compound, as defined in §115.10 of this title, is subject to the requirements of this division (relating to Cooling Tower Heat Exchange Systems) in addition to the applicable requirements of any other division in this subchapter or any other subchapter in this chapter. (b) Definitions. The following terms, when used in this division, have the following meanings, unless the context clearly indicates otherwise. Additional definitions for terms used in this division are found in §§3.2, 101.1, and 115.10 of this title (relating to Definitions). (1) Cooling tower heat exchange system--Cooling towers, associated heat exchangers, pumps, and ancillary equipment where water is used as a cooling medium and the heat from process fluids is transferred to cooling water. This does not include fin-fan coolers. This also does not include comfort cooling tower heat exchange systems (i.e., those used exclusively in cooling, heating, ventilation, and air conditioning systems). (2) Jacketed reactor--A heat exchange system where water is used as a cooling medium around a heavy walled reactor rather than a conventional heat exchanger tube design. For the purposes of this definition, a reactor is a device or vessel in which one or more chemicals or reactants, other than air, are combined or decomposed in such a way that the molecular structure of one or more chemicals are altered and one or more new organic compounds are formed. (3) Finite volume system--A system in which a fixed amount of highly-reactive volatile organic compounds is contained or circulated, and changes in the amount of highly-reactive volatile organic compound in the system can only occur through transfers into the system to maintain the system level, transfers out of the system for maintenance purposes, or leakage out of the system (e.g., a propylene refrigeration system).