GLOSSARY OF TERMS AND DEFINITIONS FOR SOLVENT CLEANING IN INDUSTRY (with a focus oil the Unit Operation System). (DRAFT) First Edition; May 1992 (First Revision; September 1993) (Second Revision; June 1993) Mohamed A. Serageldin, Ph.D. tJ.S Environmental Protection Agency Office of Air Quality Planning and Standards (MD -13) Research triangle Park, North Carolina 27711 ------- DISCLAIMER This report has - not yet been reviewed by the Office of Air Quality Planning and Standards, EPA, and approved for publication. Any error is therefore, attributable to the author. Mention of trade names or commercial products is not intended to constitute endorsement or recommendation for use. Copies of this draft glossary are available upon request. i ------- PREFACE An important element in developing effective and defensible regulations is using' consistent terminology and adopting terms that are well illustrated. It is common during development of a guidance or other technical document to fall into the trap of using jargon or misusing general terms. It is also common to see in documents that deal with a single subject the same word used inconsistently to refer to different things. For that reason early on in the cleaning project words and terms that could be misunderstood were defined. For example, the term "cleaning operation" is intentionally not used because it is sometimes being used to mean "cleaning activities" such as wiping and flushing and sometimes to mean an "item of equipment" such as a parts cleaner. The term "equipment" was also avoided when reference was made to a process or production unit to be cleaned. The preferred term is "unit operation." The importance of this distinction becomes clear in reference to the unit operation system (UOS), since several items of equipment are involved in addition to the unit operation being cleaned. Also, a multi- stage distillation column is a widely used industrial "unit operation." This process unit consists of three "items of equipment"; a multi-stage separation column, a reboiler, and a condenser). In our definition of a unit operation, we included a number of non standard chemical engineering unit operations, such as tanks and spray booth. The UOS is a new material accounting and management concept. It provides a specific approach to data recording which provides insight into the destination of all pollution from a process, whether it is allowed to enter the air, water or exit the facility as a solid waste. For this reason a number of figures and an example calculation were provided. Relevant regulatory tents were also included in an attempt to provide in one document most of necessary terminology for regulatory development. Adoption of a common terminology is the first step in furthering communication between the interested parties. Mohamed Serageldin, Ph.D. June 1993 ii ------- TABLE CONTENTS Page 1. Glossary of Terms and Definitions 1 2. Appendix A (list of figures) 11 iii ------- GLOSSARY OF TERMS AND DEFINITIONS [ref. 1] ACT; see "alternative control techniques" Alternative control techniques (ACT) [ref. 2]: - represent a series of documents which are prepared to provide technical information such as available controls for use by State and local agency to develop their regulations. Sec. 183(c) of the Clean Air Amendments tCAAA) of 1990, stipulates that ACTs "shall be issued for all categories of stationary sources of volatile organic compounds and oxides of nitrogen which emit, or have the potential to emit 25 tons or more of such air pollutants." (NOTE: The States and local agencies are not required to adopt recommendations made in an ACT as they would be in the case of a control techniques guideline, CTG.) Cleaning Activity: includes actions such as wiping, brushing, flushing, or spraying. (The term cleaning operation was intentionally not used in this list, because it is sometimes used loosely to denote a unit operation, such as a part cleaner.) Cleaning Classifications: cleaning is grouped under three main classifications: (1) Cleaning of external surfaces; (2) Cleaning of interior surfaces/containers, and (3) Cleaning of removable parts. The focus is on the "unit operation" being cleaned. Cleaning of external surfaces: under this classification, the solvent must be applied to the "external surface" being cleaned (as contrasted to the interior of tanks or pipes). The "cleaning activities" (performed manually or mechanically) may include mopping/brushing and spraying, using "cleaning tools" such as rags, brushes, mops, and spraying equipment. Surfaces that fall within this classification include rollers in printing machines, wings of aeroplane, floors, tables, and walls. Cleaning of internal surfaces/containers: under this classification the solvent must be applied to the interior .of the '"unit operation" being cleaned, whether the task is performed manually or mechanically. The "cleaning activities" may include flushing, agitation, spraying, and mopping/brushing. A combination of activities may be required, depending on the shape and size of the "unit ------- operation" and on the type residue that is being removed. Surfaces may include the inside of tanks/vessels, batch reactors, columns, heat exchanger, paint spray booths, and fuel tanks. Cleaning of parts: under this classification, the item (part) is dipped in a container of solvent during cleaning or the part is cleaned above the container by spraying or wiping. Equipment (i.e., unit operations) used for this cleaning task include part washers, batch-loaded cold cleaners, ultrasonic cleaners, and spray gun washers. The major "cleaning activity" may involve dipping or spraying. Cleaning may, also, involve brushing and wiping. Cleaning practices: means a repeated or customary action that is specific to an industry. Some cleaning practices will lead to pollution prevention and some will not. Cleaning tool: mean any item that is used for the purpose of cleaning. This includes wiping rags, brushes, scrapers, water jets Closed-loop recycling (in-process recycling) fref. 31: reuse or recirculation of a chemical material within the boundaries of a "unit operation system." However, a recovery or reclamation unit operation may be included within the boundaries of the unit operation system if the "unit" is (1) solely dedicated: the chemical is returned to be reused for cleaning that same unit operation. (2)physically integrated: connected to the unit operation being cleaned by means of piping, so that it is not possible to exclude that "unit" when performing the material balance around the unit operation system. The recovery or reclamation unit may serve for purification, extraction, distillation, filtration, adsorption or absorption. NOTE:The condition for what may be termed "closed loop recycling" is satisfied when a storage container is , involved if the entire process through completion of . reclamation, is closed, with pipes or other comparable enclosed means of conveyance. Condition No. 1 above should also be true. CTG: "control techniques guideline" - a document which ------- provides guidance to States and local agencies for reducing emissions of volatile organic compounds which contribute to (stratospheric) ozone levels in non-attainment areas. These are areas which violate the national ambient air quality standard (NAAQS) for ozone. The Clean Air Act requires that a source subject to a CTG meet reasonably available control technology (RACT). (NOTE: When EPA has issued a CTG for a source category, State and local agencies cannot set in their regulations (i.e., SIPs) RACT options for VOC sources that are less stringent than those defined in the CTG. They can, however, adopt more stringent control options. See also ACT) HAP: " hazardous air pollutants" - A list of 189 compounds established by congress. EPA may revise the list when appropriate. Life cvcle analysis (LCA): The scope of a life cycle analysis depends on the elements encompassed within the defined boundaries for the analysis. If the purpose of the analysis is to perform a hazardous materials life cycle cost analysis, then cost analysis will encompass all cost elements for all phases of the system life cycle. This includes acquisition, operation and support, and system disposal. This type of analysis provides a decison-maker with a tool for evaluating options to reduce pollution. The example discussed above has a more local or national focus. This type of analysis could be done by a plant or by an industry. The boundaries of a life cycle analysis may go beyond the national boundaries. The analysis will involve looking at the materials and processes being used to manufacture the materials purchased by an industry for use in their processes. The focus is likely to be different from one that has a local orientation. This type of outlook is more likely to be done by goverments and specialized organization (e.g., a think tank). A unit operation system provides a convenient building block for performing life cycle analyses (see unit operation system). In-process recycling: see "closed loop recycling" Line flushing [ref. 4]: The flushing unit operation is the infrequent process of completely cleaning out a paint circulating system, which includes the paint mix tanks and piping lines. This operation is only necessary when a ------- system is inadvertantly contaminated or a new color is being introduced to replace another system. Except for these special situations line flushing is done annually. Even in the case of closed-loop systems (Figure 3), some losses can occur during flushing (i.e., through various vents, from transfer operations and from paint mix tanks). The information provided by the automotive industry indicate that the loss from such system is around 10 percent for the solvents used in this unit operation system. MACT: " maximum achievable control technology" - It is the maximum degree in of reduction in emissions of the 189 hazardous air pollutants (HAPs) listed in Sec. 112 (b), including a prohibition of such emissions where achievable, taking into account the cost of reduction, and any non-air quality health and environmental impacts and energy requirements. Source which emits per year, 10 tons of one or 25 tons of one or more of the HAPs should meet MACT set by EPA for that source category. Maior source; means any stationary source or group of stationary sources located within a contiguous area and under common control that emits or has the potential to emit considering controls, in the aggregate, 10 tons per year or more of any hazardous air pollutant or 25 tons per year or more of a combination of hazardous air pollutants, Sec. 112 (a)(1). Masking Agents: means a translucent or opaque material used to cover/shield all or parts of a surface. Masking agents are used in spray-booths to reduce the amount of solvent needed for cleaning. Nonattainment: "Any area that does not meet (or that contributes to ambient air quality in a nearby area that does not meet) the national primary or secondary ambient air quality standard for pollutant," Sec. 107(d)(i). Normalizing Parameters [ref. 5]; means a parameter for making the emissions and other pollution data more useful. Emission data in mass/time are not very useful for comparing emissions from, e.g, two tank unit operation systems (UOSs), if the size, number of tanks, solvent used, and time spent cleaning are different in each case. An appropriate normalizing parameters would be the total surface area cleaned as this parameter may determine how much solvent is ------- needed for cleaning and may also influence the rate of evaporative emissions and solvent waste generated. The new units would be mass per time per surface area cleaned. The adoption of such units will generate usage factors representative of certain cleaning scenarios. On-site recycling (inside the boundaries of a facility) Fref. 31 : means the reclamation of a solvent waste stream that is returned to a different process other than from which it was generated. This stage should be presented as an independent "unit operation system," with the recovery or reclamation unit operation (distillation, filtration, etc.,) clearly defined. All storage containers directly connected to the recovery or reclamation unit operation should be included within the boundaries of the unit.operation system. The emissions will also include solvent loss during cleanup of the unit operation used for solvent reclamation in addition to that accounted for on the basis of the efficiency of the separation process. Activities performed on-site which change the chemical nature of the solvent, such as combustion or acid neutralization are not included under this definition. They are considered to be treatment operations. Off-site recycling (outside the boundaries of a facility) fref. 31: reuse or further use of a chemical material accomplished after a recovery" or reclamation step. If the reuse or further use of the chemical material is accomplished without such a step the chemical material is considered a feed stock for an off-site use. Activities performed off-site which will change the chemical nature of the contaminated material, such as combustion or acid neutralization are not included under this definition. They are considered to be "treatment operations." Activities performed off-site which change the chemical nature of the solvent, such as combustion or acid neutralization are not included under this definition.' They are considered to be treatment operations. Ozone: a compound made up of three atoms of oxygen. This compound is formed by reaction between volatile organic compounds and nitrogen oxides. The reaction is energized by sunlight. ¦ . ------- o Pollution Prevention: involves practices aimed at eliminating the creation of emissions or wastes at the source. The practices include the use of new materials, modification of equipment, and work practice changes. Closed loop recycling is an acceptable pollution prevention practice. o Purging [ref 4]: The purging unit operation is the process wherein individual paint applicators and/or small portions of the paint line are emptied of one coating color, cleaned and then filled with another coating color. This process may one or more times in one day depending on the cleaning practices adopted by a plant. o Product substitution: means the replacement of any product intended for an intermediate or final use with another product intended and suitable for the same intermediate or final use. This is considered a source reduction activity if either the VOC emissions or the quantity of waste generated is reduced. o Protective covers: see "masking agents" o RACT: see "reasonably available control technology" o Reasonably available control technology [refs, 6 and 7]: a control option to limit emissions from existing sources in nonattainmnet areas. It is the lowest emission limit that a particular source is capable of meeting by the application of control technology that is both reasonably available, as well as technologically and economically feasible RACT is defined in control technique guidelines (CTGs). o Recycling: A material is "recycled" if it is used, reused, or reclaimed (40 CFR 261.1 (b)(7)). A material is "used or reused" if it is either employed as an ingredient (including' its use as an intermediate ) to make a product ; however a material will not satisfy this condition if distinct components of the material are recovered from metal-' containing secondary materials) or employed on a particular function as an effective substitute for a commercial product (40 CFR 26.1(c)(5)). A material is "reclaimed" if it is processed to recover a useful product or if it is regenerated . Examples include the recovery of lead values from spent batteries and the regeneration of spent solvents 6 ------- (40 CFR 261.1(c)(4). [See also closed-loop recycling (in- process recycling); on-site recycling; and off-site recycling.] o Reclaimed fref. 2: A material is "reclaimed" if it is processed to recover a usable product or if it is regenerated, (see recycling). o Source reduction fref. 21: means any activity or treatment that reduces or eliminates the generation of VOC emissions or waste. This includes (1) product substitution or elimination, (2) technology changes, and (3) work practice related changes. o Stationary source: means any building, structure, facility, or installation which emits or may emit any air pollutant, Sec. Ill (a)(3). o Source category: this term is used in reference to a list (being developed by EPA) of all categories and subcategories of major sources and area sources of the 183 HAP pollutants listed in Sec. 112(b). For example, the source categories Aerospace industries, Auto and Light Duty Truck (surface coating), and Flat Wood Paneling (surface coating) are listed under the industry group " Surface Coating Processes." A more complete list is given in Table 3.1 [ref. 83. o Summary table of UOSs: plant wide solvent usage, emissions, and waste can be summarized in convenient tables such as that shown in Figure 5 to olan pollution prevention objectives. o ' Treatment fref. 21: It involves destruction or degradation of the waste to produce material that is less toxic and has a lower environmental risk impact, (see recycling). o Unit operation (UP): means an industrial operation , classified or grouped according to its function in an operating environment. There may be considerable variation in unit operations from one industry to another. For example a distillation column, a paint mixing vessel (tank), a spray booth, a parts cleaner and a printing machine. A unit operation may involve one or more items of equipment, 7 ------- e.g., a unit operation may include both a reactor and a mixing vessel or several mixing vessels. Unit Operation System (UPS): means the ensemble on which the material balance is performed. It includes all possible points/sources leading to evaporative emission losses associated with the cleaning of a primary "unit operation," including losses during dispensing of solvent, handling residual in cleaning tools (such as rags), solvent storage and so on. (Examples of "primary" unit operation systems are given in Figures 1 and 2 (for different control situations). A "primary" unit operation system is the UOS that An item of equipment that is used or designed for cleaning parts is also a unit operation by definition, therefore losses during removal of parts should also be considered. Emissions from solvent waste management unit operations (e.g., recycling and treatment) result in "secondary emissions." Emissions from each of the secondary unit operations may be represented independently. They should be computed from the corresponding UOSs - with all input and output streams clearly identified. When such units, however, are considered to be an "integral part" of the "primary" "unit operation," the waste management unit should be shown inside the boundaries of the UOS of which it is an inseparable part (Figure 3). All input and output streams for a UOS must, however be clearly identified. Emissions from storage tanks containing virgin solvent should be properly apportioned among the UOSs. This "cradle to grave" material accounting concept is illustrated in Figure 4. Used or reused Tref. 21: A material is "used or reused" if it is either (1) employed as an ingredient (including use as an intermediate) in an industrial process to make a product (for example , distillation bottoms from one process used as feedstock in another process). This term is used under recycling. VOC: see "volatile organic compound" Volatile organic compound (VOC); means any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic, carbides or carbonates, and ammonium carbonate which"participate in atmospheric photochemical reactions. That is any organic compound other than those the (EPA) administrator designates as having negligible photochemical 8 ------- reactivity. The excluded compounds are mentioned in 40 CFR Part 51, Vol. 57, No. 22, p. 3945, February 3, 1992. VOCs may measured by EPA reference methods 24 and 24A (40 CFR Part 60, Appendix A) or any approved equivalent method. o Waste Minimization fref. 21; means the reduction, to the extent feasible, of hazardous waste that is generated or subsequently treated, stored or subsequently treated, stored or disposed of. It includes any source reduction or recycling activity undertaken by a generator that results in either (1) the reduction of total volume or quantity of hazardous waste, or both, so long as such reduction is consistent with the goal of minimizing present and future threats to human health and the environment. In order of preference these are: source reduction, recycling, and treatment. o Water blasting: a cleaning practice which involves spraying high pressure water on a surface to remove contaminants. o Work practice: The main focus here is on the human aspects of the industrial activities. This term is reserved for specific industrial activities that lead to a reduction in VOC emissions or waste. The activities include increased operator training, management directives, segregation of the waste solvent, practices that lead to a reduction in cleaning frequency. It does not include the use of equipment, such as solvent dispensers or modification of an item of equipment. References: 1. M. A. Serageldin , "List of Definitions Applicable to the Unit Operation System," Revised September 1992. US EPA;OAQPS (MD-13) RTP 27711. 2. The Clean Air Act Amendments of 1990, in Environmental Law. Document prepared for the use of the Committee on Energy and Commerce, House of Representatives, April 1991. U.S. Government Printing Office (pp 159, 192, 607). 3. "Pollution Prevention 1991: Progress on Reducing Industrial Pollutants," Office of Pollution Prevention, Washington, D.C. 20460; EPA21P-3003, October 1991. 4. Letter from Prachan, E. A., American Automobile Manufacturing Association (AAMA), to Serageldin, M. A., EPA/OAQPS; January 13, 1933. 9 ------- 5. M.A. Serageldin, "Different Approaches for Standards Development (with an introduction to the unit operation system concept), (revised draft, September 30, 1992); US EPA,* OAQPS (MD - 13), RTP, NC 27711. 6. "Glossary of Environmental Terns And Acronym List," US EPA; Office of Communications And Public Affairs (A-107); Washington DC, 20460; December 1989 19K-1002. 7. EPA Guideline Series: Control of Volatile Organic Emissions from Existing Stationary Sources - Volume II (Surface Coating of Cans, Coils, Paper, Fabrics, Automobile, and Light-Duty Trucks) EPA - 450/2-77-008 (OAQPS No. 1.2-073) May 1977. 8. Documentation for Developing the Initial Source Category List (Final Report). US EPA; OAQPS; RTP, NC 27711; EPA-450/3 - 91- 03 0, July 1992. EPA\DEF0693.MAS Please address comments to Mohamed Serageldin, (919) 541-2379: OAQPS; MD-13; RTP NC 27711. 10 ------- V1 Solvent Recovered (contaminant free) Paint Line Flushing (closed loop) UOS (controlled emissions) (R = dedicated recycling unit operation) FIGURE 3 NOTE: Illustration copied from drawing provided by GM corporation ^Dearborn, Ml)for the cleanup solvent project) _ October 1991 13 ------- Virgin Solvent Storage Primary Unit Operation System Emissions = + V2 + V3 Waste Solvent Storage System Boundary Emission Unit Operation System - uos ( Primary and Secondary UOSs) FIGURE 4 14 ------- Summary of VOC Emissions (Ib/yr) SOLVENT UNIT OPERATING SYSTEM SOLVENT TOTAL 1 2 3 4 5 ...15 A B C UOS TOTAL PLANT TOTAL FIGURE 5 15 ------- EXAMPLE (Primary Unit Operation System) EVAPORATIVE LOSS. V, (654) EVAPORATIVE LOSS, V2 (1.570) EVAPORATIVE LOSS, Vj (392) SYSTEM BOUNDARY SOLVENT INPUT, S, ¦ (9.810) SOLVi CONT, ENT UNER USED SOLVENT OUTPUT, Sq(I-Xci) (7,194) S| (base ami.) - 330 gal/tank/changeout x 2 tanks x 1 change out/yr x 10.9 lb/gal - 7,194 Ib/yr S| (replenish) - 0.05 gal/station/operation x 2 stations xtO operations/day x 240 days/yr x 10.9 to/gal-2,616 Ib/yr St > St (base amt.) + St (replenish) - 7,194 to/yr + 2,616 to/yr - 9,810 to/yr Vtot* V1+V2+V3 - SrSo (1-Xd) Vtot- 0.05 gal/station/operation x 2 stations x 10 operations/day x 240 days/yr x 10.9 lb/gal« 2,616 to/yr vr- (0.25) 2,616 to/yr - 654 Ib/yr V2* - (0.60) 2,616 Ib/yr -1,570 Ib/yr V3# - (0.15) 2,616 to/yr - 392 lb/yr Xci - 0.23 (i.e., 23 percent contamination by weight)" Vtot-St-So (1-Xct) So-(SrVTOT)/(i-Xci) So - (9,810 Ib/yr - 2,616 to/yr) / (1 -0.23) So - 9,343 to/yr So (1-Xci) - 9,343 Ib/yr (1-0.23) - 7,194 to/yr * Breakdown of Vtot estimated by facility manager ** Average provided by (reclamation facility) for PRC's Note: Ibs/yr represent total Ibs/yr from 2 stations described by this operation Figure le. Clean-up No5-Mixer Parts Cleaning ------- |