{"data":{"id":"us/40-cfr-60.661a","jurisdiction":"us","citation":"40 CFR 60.661a","heading":"a What definitions must I know?","body":"As used in this subpart, all terms not defined herein have the meaning given them in the Clean Air Act and subpart A of this part.\nBatch distillation operation means a noncontinuous distillation operation in which a discrete quantity or batch of liquid feed is charged into a distillation unit and distilled at one time. After the initial charging of the liquid feed, no additional liquid is added during the distillation operation.\nBreakthrough means the time when the level of TOC, measured at the outlet of the first bed, has been detected is at the highest concentration allowed to be discharged from the adsorber system and indicates that the adsorber bed should be replaced.\nBoiler means any enclosed combustion device that extracts useful energy in the form of steam.\nBy compound means by individual stream components, not carbon equivalents.\nClosed vent system means a system that is not open to the atmosphere and is composed of piping, ductwork, connections, and, if necessary, flow inducing devices that transport gas or vapor from an emission point to a control device.\nContinuous recorder means a data recording device recording an instantaneous data value at least once every 15 minutes.\nDistillation operation means an operation separating one or more feed stream(s) into two or more exit stream(s), each exit stream having component concentrations different from those in the feed stream(s). The separation is achieved by the redistribution of the components between the liquid and vapor-phase as they approach equilibrium within the distillation unit.\nDistillation unit means a device or vessel in which distillation operations occur, including all associated internals (such as trays or packing) and accessories (such as reboiler, condenser, vacuum pump, steam jet, etc.), plus any associated recovery system.\nFlame zone means the portion of the combustion chamber in a boiler or process heater occupied by the flame envelope.\nFlow indicator means a device which indicates whether gas flow is present in a vent stream.\nFuel gas means gases that are combusted to derive useful work or heat.\nFuel gas system means the offsite and onsite piping and flow and pressure control system that gathers gaseous stream(s) generated by onsite operations, may blend them with other sources of gas, and transports the gaseous stream for use as fuel gas in combustion devices or in in-process combustion equipment such as furnaces and gas turbines either singly or in combination.\nHalogenated vent stream means any vent stream determined to have a total concentration (by volume) of compounds containing halogens of 20 ppmv (by compound) or greater.\nIncinerator means any enclosed combustion device that is used for destroying organic compounds and does not extract energy in the form of steam or process heat.\nPressure-assisted multi-point flare means a flare system consisting of multiple flare burners in staged arrays whereby the vent stream pressure is used to promote mixing and smokeless operation at the flare burner tips. Pressure-assisted multi-point flares are designed for smokeless operation at velocities up to Mach = 1 conditions (i.e., sonic conditions), can be elevated or at ground level, and typically use cross-lighting for flame propagation to combust any flare vent gases sent to a particular stage of flare burners.\nPrimary fuel means the fuel fired through a burner or a number of similar burners. The primary fuel provides the principal heat input to the device, and the amount of fuel is sufficient to sustain operation without the addition of other fuels.\nProcess heater means a device that transfers heat liberated by burning fuel to fluids contained in tubes, including all fluids except water that is heated to produce steam.\nProcess unit means equipment assembled and connected by pipes or ducts to produce, as intermediates or final products, one or more of the chemicals in § 60.667a. A process unit can operate independently if supplied with sufficient fuel or raw materials and sufficient product storage facilities.\nProduct means any compound or chemical listed in § 60.667a that is produced for sale as a final product as that chemical, or for use in the production of other chemicals or compounds. By-products, co-products, and intermediates are considered to be products.\nRecovery device means an individual unit of equipment, such as an absorber, carbon adsorber, or condenser, capable of and used for the purpose of recovering chemicals for use, reuse, or sale.\nRecovery system means an individual recovery device or series of such devices applied to the same vent stream.\nRelief valve means a valve used only to release an unplanned, nonroutine discharge. A relief valve discharge results from an operator error, a malfunction such as a power failure or equipment failure, or other unexpected cause that requires immediate venting of gas from process equipment in order to avoid safety hazards or equipment damage.\nTotal organic compounds (TOC) means those compounds measured according to the procedures in Method 18 of appendix A-6 of this part or the concentration of organic compounds measured according to the procedures in Method 21 or Method 25A of appendix A-7 of this part.\nVent stream means any gas stream discharged directly from a distillation facility to the atmosphere or indirectly to the atmosphere after diversion through other process equipment. The vent stream excludes equipment leaks including, but not limited to, pumps, compressors, and valves.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER C—AIR PROGRAMS","PART 60—STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES","Subpart NNNa—Standards of Performance for Volatile Organic Compound (VOC) Emissions From Synthetic Organic Chemical Manufacturing Industry (SOCMI) Distillation Operations for Which Construction, Reconstruction, or Modification Commenced After April 25, 2023"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"d084a73541d0ce7a5da74ae14a79a23c14240f655c6b70ff0d0d7fabcd556976","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-60.660a","next":"us/40-cfr-60.662a"},"notice":"GroundRules: Original legal text. Not legal advice."}