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Adsorptive Cartridge Filters - Filters that contain clay or clay and activated carbon. These filters are designed to remove insoluble soil and non-volatile residue along with dyes from solvent. See Cartridge Filters.

Aeration - See Deodorizing Cycle.

Air Bumping - See Bumping.

Amyl Acetate – A dry-side spotting agent used to remove oil base stains and plastics.

Anionic Detergent System - A drycleaning detergent that is negatively charged. These detergents carry water by solubilization. Anionic detergents are used in charged systems.

Atmospheric Still - A distillation device that operates without the need for internal pressure or vacuum. All drycleaning stills designed for use with chlorinated solvents are atmospheric.

Azeotropic Distillation - The distillation of a mixture with components having constant maximum and minimum boiling points, with the components being distilled without decomposition, and in a fixed ratio.


Backwashing - A method used to remove spent powder filtration material (diatomite) from tubular filters. In this operation, the solvent flow is reversed to wash the spent filter powder off the tubular filters. See Bumping.

Base Tank - A solvent storage tank located at the base of a drycleaning machine. Normally there are two or three of these per machine. One base tank contains clean solvent and one contains dirty solvent to be distilled.

Bath Operation or Bath System - In this drycleaning solvent system, a fixed quantity of solvent is issued for one operation. Solvent is not circulated during the wash cycle. Solvent introduced in the washer is used for the entire load.

Batch Operation - A drycleaning solvent system in which there is continuous circulation of drycleaning solvent. Detergent and sometimes water are added into a wash solvent tank. The entire wash solvent is “charged” with detergent (or detergent is injected). The concentration of detergent in this charged system is one to two percent. This is also known as Batched Detergent Injection.

Benzine - See Naphtha.

Bleach - A chemical or chemical mixture used in pre-spotting, spotting and laundry operations to decolorize stains and soiled areas. There are two types of bleaches: oxidizing and reducing.

Body Feed - The fresh filter powder (diatomite) added at the beginning of each filtration cycle in a non-regenerative powder filtration system.

Boil Down - The last phase of the solvent distillation process in which the still kettle temperature is increased to recover additional solvent.

Boiler - An enclosed vessel in which water is heated and circulated either as hot water or steam. Drycleaning operations utilize boilers as a heat and steam source for distillation operations; heating air for drying operations; pre-cleaning and spotting operations; steam pressing operations; steam cleaning of equipment, and steam stripping of carbon adsorption units and cartridge filters.

Boiler Blowdown Water - Water generated from the process where the steam and water is discharged from the boiler. This discharge blowdown is part of boiler maintenance to prevent scale buildup.

Boilover - The Discharge of still bottoms/muck from a distillation unit or muck cooker. The cause of boilover is usually caused by overfilling the distillation unit/muck cooker but can be caused by operating the unit at too high a temperature.

Bound Moisture - Water held and dispersed by a detergent in a drycleaning solvent.

Buck – The bottom plate of a steam press. The garment to be finished (pressed) is placed on the buck.

Bump Action Filters - See Regenerative Filters.

Bumping - The removal or dislodging of spent powder filtration material (diatomite and activated carbon) from flexible tubular filters by flexing or agitating or by using compressed air (air bumping).

Button Trap - A drycleaning machine device located in front of the solvent pump that prevents objects (lint, fasteners, buttons, coins etc.) from entering the solvent pump.

Butyl Hydroxyl Toluene (BHT) - An antioxidant commonly added to petroleum drycleaning solvents to prevent odor problems (odor inhibitor). Some re-claimed PCE contains BHT as an additive (color inhibitor). Also known as Butylated Hydroxyl Toluene.


Carbon Adsorber - A bed of activated carbon into which an air-solvent vapor stream is routed and which adsorbs the solvent on the carbon. Carbon adsorption systems can handle high air flow rates with low solvent concentrations and reduce solvent vapors in exhaust by 95%. Also known as a Vapor Adsorber or Sniffer.

Cartridge Filter - A replaceable filter used in the wash cycle consisting of an outer metallic perforated shell enclosing a pleated paper filter element around a perforated activated carbon or clay-filled canister having a central perforated center post with a fine-mesh wrap. Cartridge filters are the most widely used filters in drycleaning today.

Cationic Detergent - A drycleaning detergent that is positively charged. Cationic detergents carry water by means of an emulsion. They provide excellent water-soluble soil removal. These detergents are used in injection systems. See injection system.

Centrifugal Disc Filter - See Spin Disc Filter.

CFC-113 - See Valclene.

Charged System - A drycleaning solvent/detergent system in which detergent is added to the solvent or “charged” as a certain percentage of the solvent (normally 1 to 2%) to maintain a continuous concentration of detergent. Charged systems use anionic detergents.

Chiller - See Refrigerated Condenser.

Classification - In the drycleaning operation, this is the separation of clothes into similar groups that may be drycleaned together. This separation involves classifying garments on the basis of their weight, color, and finish before cleaning. This breakdown assures that clothes cleaned together are compatible and receive treatment appropriate for their type.

Clean Air Act Amendments (CAAA) - The 1990 amendments to the Clean Air Act (1970) added comprehensive provisions to regulate emissions of toxic air pollutants, acid rain, and substances that threaten the ozone layer. Additionally, the 1990 amendments added a permit program and greatly strengthened enforcement provisions and requirements for non-attainment areas, mobile source emissions, and automotive fuels.

Closed-loop Machine - A dry-to-dry machine which recirculates solvent-laden vapor through a primary control system (e.g. refrigerated condenser) with no exhaust to the atmosphere during the drying cycle. A closed-loop machine may allow for venting to the ambient air through a local exhaust ventilation system, such as a door fan, after the drying cycle is complete and only while the machine door is open.

Coalescer - A filter designed to separate water from solvent.

Cold Machine - See Transfer Machine.

Cold Spotting Board - A spotting board that is not supplied with steam. See Spotting Board.

Condensate Water - Any drycleaning wastewater derived from the condensation of distilled solvent vapors, dryer vapors, or steam.

Condenser - A device used to chill hot solvent vapors and recover liquid solvent. Condensers are generally used during the drying cycle and when operating the still, muck cooker, or vapor recovery unit.

Constant Pressure Filter - A powder filtration system in which constant solvent pressure is exerted on the filter in order to keep the filter coated with filter powder.

Contact Water - Any wastewater stream that has been in contact with drycleaning solvents or drycleaning solvent vapors. Contact water, therefore, contains solvent.

Converted Machine - An existing vented drycleaning machine that has been modified to be a closed-loop machine by eliminating the aeration step, installing a primary control system, and providing for re-circulation of solvent-laden vapor with no exhaust to the atmosphere or workroom during the drying cycle. A converted machine may allow for venting to the ambient air through a local exhaust ventilation system, such as a door fan, after the drying cycle is complete and only while the machine door is open.

Cooked Powder Residue - The waste material generated by cooking down or distilling muck. Cooked powder residue is a hazardous waste and will contain solvent, powdered filter material (diatomite), carbon, non-volatile residues, lint, dyes, grease, soils and water.

Cooker - See Muck Cooker.

Cool-down - The portion of the drying cycle that begins when the heating mechanism deactivates and the refrigerated condenser continues to reduce the temperature of the air recirculating through the drum to reduce the concentration of solvent in the drum.

Cylinder - The rotating drum of a drycleaning machine or dryer where the clothes are placed.


Decamethylcyclopentasiloxane - (a.k.a. D5) See GreenEarth.

Deodorizing Cycle - The last stage of the operation of the reclaiming dryer. At this point, the air inlet and exhaust valves are opened and a stream of cool outside air strips away the last solvent vapors. If properly done, the clothing should be left dry and virtually odor-free. Also known as Aeration.

Desorption - Regeneration or stripping of an activated carbon bed, or any other type of vapor absorber by removal of the adsorbed solvent using hot air, steam or other means.

Detergent - An additive routinely added to solvent to assist in removing water-soluble soils and stains that are not ordinarily soluble in solvent alone.

DF-2000TM - A petroleum drycleaning solvent manufactured by Exxon Chemical. DF-2000 is a so-called synthetic petroleum drycleaning solvent that has a high flash point (137° F). DF-2000 is composed of isoparafins – reportedly primarily C11 – C12.

Diatomaceous Earth or Diatomite - A siliceous powder composed of the remains of microscopic single cell aquatic plants. It is used as the filter media in powder filtration systems. This powder builds up on a supporting frame and forms a porous surface. Also known as Filter Powder.

Digestive Agent - A pre-cleaning or spotting agent which is a mixture of enzymes used to digest food and albuminous-type stains.

Disposable Lint Bags - Filter bags designed by Lint-All that replace cloth lint bags or sponge lint filters in the lint trap in drycleaning machines, to improve filtration, airflow, maintenance, and the environment.

Distillation - A process by which solvent is separated from non-volatile and other impurities by boiling The used or contaminated solvent is heated and vaporized, then condensed into a solvent/water mixture, which after separation yields a pure solvent. The contaminants are left behind as a residue or sludge.

Diverter Valve - A flow control device that prevents room air from passing through a refrigerated condenser when the door of the drycleaning machine is open.

Door Fan - A local exhaust ventilation system designed to provide for a minimum 100 fpm inward air velocity or equivalent into the effective door open area of a drycleaning machine whenever the door is opened, and where the solvent emissions are controlled by a carbon absorber or equivalent control prior to venting to the outer air.

Dosimeter Badge - A device for measuring the amount of organic vapors a person is exposed to during a set time period, or the vapor concentration in a given area.

Dow-per– Trade name for drycleaning perchloroethylene manufactured by Dow Chemical.

Drum - See Cylinder.

Drycleaning - The process used to remove soil, greases, paints and other unwanted substances from articles with organic solvents.

Drycleaning Control System - Equipment (e.g. carbon absorber, refrigerated condenser, azeotropic unit, etc.) or an air cleaning device used to reduce the amount of air pollutants in an air stream prior to discharge to the atmosphere.

Dryel – A home drycleaning product developed by Proctor & Gamble. Clothing is placed in a bag containing the product and the bag is placed in a dryer. Vapors, activated from the heat of the dryer penetrate the clothing and “lift” the odors and soils from the clothing.

Drycleaning Machine - A dry-to-dry machine and its ancillary equipment or a transfer machine system and its ancillary equipment.

Drycleaning Solvent - Nonaqueous solvents used in the cleaning of clothing and other fabrics.

Dryer - See Reclaimer and Tumbler.

Drying Cabinet - A housing in which materials that have been previously drycleaned in solvent are dried instead of being dried by tumbling in a drycleaning machine. Solvent can be recovered from cartridge filters by a drying cabinet. Air or steam is pulled over cartridges and then routed to a carbon absorber where it can be recovered by stripping and separation. Also known as a Steam Cabinet.

Drying Cycle - The operation used to actively remove the solvent remaining in the garments after washing and extraction. For closed-loop machines, the heated portion of the cycle is followed by cool-down and may be extended beyond cool-down by the activation of a control system. The drying cycle begins when heating coils are activated and ends when the machine ceases rotation of the drum.

Drying Efficiency - See Reclamation Efficiency.

Dry-side Spotting Agent - A non-aqueous solvent used to pre-clean or “spot” non-water soluble stains or soils.  

Dry-to-Dry Machine - A drycleaning machine, in which both cleaning and drying cycles are performed in the same wash wheel. Because the dry-to-dry machine is completely enclosed during the entire cycle, releases of solvent fumes to the plant atmosphere are minimized. Also known as a “Hot” Machine.

Dyna CleanTM System - A drycleaning solvent purification system that utilizes azeotropic distillation.

Dyna PurTM Process - A solvent purification process that employs a permanent stainless steel filter with a fabric lining. Dirt and other contaminants are routinely backwashed off the filter with clean solvent. The contaminated solvent is distilled azeotropically to separate the perc from other components. As with other systems, the solvent/water vapor mixture produced during distillation is condensed and the solvent and water are separated. The steam condensate contains soils, other contaminants, and any perc residual is then discharged.


EPA Identification Number - A unique number assigned by EPA to each generator or transporter of hazardous waste and each hazardous waste treatment, storage or disposal facility.

Evaporator - A wastewater pre-treatment device that volatilizes solvent from the waste stream in a single pass prior to discharge. Normally, the water is filtered through an activated carbon or polymer filter to reduce solvent concentrations.

Exhaust Damper - A flow control device that prevents the air-solvent vapor stream from exiting the drycleaning machine into a carbon absorber before room air is drawn into the drycleaning machine.

Extraction - The step that usually follows immediately after the completion of the wash cycle and drain period. During extraction, the wash wheel is accelerated to speeds of 350 to 450 rpm, causing much of the solvent to spin free of the fabric.

Extractor - A vertical axis centrifuge which removes most of the drycleaning solvent from the clothing after the “wash” phase is finished.


Filter Cake - See Muck.

Filter Muck - See Muck.

Filter Powder - See Diatomaceous Earth.

Filter Soap - An early drycleaning detergent composed of petroleum sulfonates and other sulfanates. These soaps are soluble in drycleaning solvent and can therefore pass through filters, hence the name filter soaps.

Finishing - Pressing of garments to remove wrinkles and restore each garment to its original size, shape and appearance. Pressing equipment is heated with superheated steam.

First Generation Drycleaning Machine - See Transfer Machine.

140° Flash Solvent - A petroleum distillate drycleaning solvent with a higher flash point (flash point of 140° F) than common petroleum solvents, thus reducing its fire hazard. The distillation range for this solvent is 350 - 410°F. Also known as 140° F Solvent.

Flexible Tube Filters - See Regenerative Filters.  

Fourth Generation Drycleaning Machine - A non-vented, closed loop process machine (dry-to-dry) with an additional internal vapor recovery device. The control technologies used in these machines are refrigerated condensers and carbon absorbers.

Freon 113 - See Valclene.

Fugitive Vapors - Vapors that escape from process equipment (such as a drycleaning machine).

Full-size Carbon Unit - A carbon unit that is used to adsorb solvent from a drycleaning machine when the vapors are re-circulating or venting from the drum during the drying cycle (normally used on first and second generation equipment).


General Exhaust Ventilation System - A mechanical exhaust ventilation system consisting of fresh air makeup inlets and one or more exhaust fans in a drycleaning facility, that primarily exhausts a drycleaning workroom; also used with a room enclosure.

Graying - Discoloration of garments caused by soil particles flocculating or being adsorbed back onto the garment surface. The chief cause of graying is dirty solvent.

GreenEarth - A recently-developed silicone-based drycleaning solvent (chemical name is decamethylcyclopentasiloxane) developed by General Electric and offered as an alternative to chlorinated and petroleum-based drycleaning solvents. Reportedly has a flash point of 170 ° F and a boiling point of 420° F.


Halogenated-hydrocarbon Detector - A portable device capable of detecting vapor concentrations of perchloroethylene and indicating an increasing concentration by emitting an audible signal or visual indicator that varies as the concentration changes.

Heating Coil - A device used to heat the air stream circulated from the drycleaning machine drum after perchloroethylene has been condensed from the air stream and before the stream reenters the drycleaning machine drum.

Hot-Head Press - A type of steam press with a smooth, non-porous stainless steel head. The head is heated by steam to surface temperatures as high as 300° F. The hot-head press is used to finish silks and silk-like fabrics.

Hot Plate Evaporator - A device that utilizes a heating coil to vaporize (or boil-off) wastewater at a drycleaning facility – primarily separator water and vacuum press water.

Hydrogen Peroxide - A common oxidizing bleach used in pre-cleaning and spotting operations. Normally a 3% hydrogen peroxide solution is used. Hydrogen peroxide is used to remove organic stains.


Inductive Fan - A fan in a drycleaning machine that draws air into the machine when the machine door is opened. This reduces exposure to the drycleaning workers to emissions of solvent vapors.

Injection System - A drycleaning solvent/detergent system in which solvent is added to the wheel saturating the garments and then detergent is injected into the flow line or into the drum by a pump or dump method. Cationic detergents are used in injection systems.

Insoluble Soil - The most commonly found materials in fabrics and the bulk of the soils removed in the drycleaning process. Examples include earth, concrete dust, sand, carbon, ashes, lint, hair and cosmetics, etc. These soils will not dissolve either in drycleaning solvent or water. Insoluble soils are removed in the drycleaning machine by lubrication and emulsification.

International Fabricare Institute (IFI) - A private international organization headquatered in Silver Spring, Maryland, that represents professional drycleaners. IFI provides research, testing services, and education for drycleaners.


Jumbo Split Cartridge Filter - A cartridge filter (carbon, carbon-clay mix or carbonless) whose dimensions are 3 1/4 inches by 9 inches.

Jumbo Full Size Cartridge Filter - A cartridge filter (carbon, carbon/clay mix or carbonless) whose dimensions are 13 1/4 inches by 18 1/8 inches.


Kauri-Butanol Value (KBV) - The solvent-soluble soil removing capability of a liquid. A solvent with a high KBV values is usually more efficient in removing oil and grease stains, but a lower KBV value may be safer on some dyes, adhesives, and trim fabrics.


Laundering - In contrast to drycleaning which uses a solvent as the principal cleaning medium, wetcleaning uses water. This process may be used occasionally by a drycleaner when a drycleanable garment is heavily stained with water soluble soils. Also known as Wet Wash.

Lint - Dust, hair, fibers and other fine particles that accumulate together.

Lint Trap - A compartment in a drycleaning machine that utilizes filter media to trap lint in the air stream.

Liquid Carbon Dioxide - A recently developed alternative to chlorinated and petroleum-based drycleaning solvents.

Loading Factor - The optimum weight of clothes that can be properly cleaned in a particular machine. This takes into account the size of the wheel (or tumbler), the type of process used, and the solvent used.


Marking - Process of identifying garments by attaching tags to each garment or stamping an identification code onto an inner surface of the garment. It is the first operation performed in a drycleaning plant.

Mister - A wastewater treatment device that sprays drycleaning wastewater that has been filtered through activated carbon or polymer filter into the air for disposal.

Muck - The residue from a powder filtration system which consists of diatomite (diatomaceous earth), spent solvent, non-volatile residues, greases, lint, soils, water, and sometimes carbon. Also known as Filter Cake or Filter Muck.

Muck Cooker - A distillation device in which live steam is used to heat solvent-laden waste (muck) from powder filtration systems to volatilize and recover solvent. Also known as a Cooker.


Naphtha - A petroleum or coal tar distillate composed largely of aliphatic hydrocarbons. Naphtha has been used as a drycleaning solvent. Also known as Benzine.

National Emission Standards for Hazardous Air Pollutants (NESHAP) - Air standards for pollutants proposed in December 1991 under the Clean Air Act Amendments. Promulgated in 1993, NESHAP requirements for the perchloroethylene drycleaning industry prohibit the sale of new transfer machines, require retrofitting of existing drycleaning equipment with control devices and require new machines to be sold with such equipment.

Non-ionic Detergent - A drycleaning detergent that has no charge. These detergents carry water by means of solubilization. Non-ionic detergents are used in charged systems.  

Non-volatile Residue (NVR) - The bulk of the residue left in the still after the solvent has been distilled out. NVR is made up primarily of oily, fatty, gummy and insoluble soils removed from clothing.


Oxidizing Bleach - A bleach that utilizes an oxidation process to decolorize stains or soiled areas. Examples are: sodium perborate, hydrogen peroxide and sodium hypochlorite.


PCE - See Perchloroethylene.

Perc - See Perchloroethylene.

Percent Detergent - The ratio of detergent to solvent used in the drycleaning cycle. Most charged solvents contain a “percent detergent” between one half and one and one-half percent, depending on the drycleaning system being used.

Perchloroethylene - A completely halogenated (chlorinated) ethene. This chlorinated hydrocarbon has excellent cleaning and degreasing properties, and is the predominant solvent used in the drycleaning industry. Also known as Tetrachloroethylene, Tetrachloroethene, Perc or PCE.

Perklone® - Trade name for perchloroethylene drycleaning solvent manufactured by ICI.

Per Sec® - Trade name for perchloroethylene drycleaning solvent manufactured by Vulcan Chemicals.

Petroleum Drycleaning Solvents - Drycleaning solvents that are petroleum based. These are solvents are blends of distillate fractions produced at petroleum refineries. Most are mixtures of as many as 200 different compounds and have a variable composition (generally C5 - C16). Their flash points range from 105° F to 147° F. (New higher flash point so-called synthetic petroleum solvents are being developed). There are many names for these solvents including: Stoddard solvent, mineral spirits, 140° flash solvent, quick-dry solvent, etc. The earliest petroleum drycleaning solvents were kerosene, gasoline, benzene and naphtha.

Petroleum Sulfonate - An early drycleaning detergent (a filter soap). It is a sulfonate of mixed hydrocarbons of petroleum origin. Petroleum sulfonates was the original charged-system detergent. Also known as Mahogany Sulfonate.

Petro-miser - Petroleum solvent dryer (reclaimer) that reclaims petroleum solvent.

Picrin - Trade name for one of the more commonly used dry-side spotting agents. The predominant constituent of Picrin is trichloroethylene.

Polish Filter - A filter housing that utilizes filter cartridges to filter fine particles from solvent after the main filter. Mainly used to control redeposition (graying).

Polishing Filter - A filter used to remove small particles of carbon or soil that have not been captured by the main filter and can effectively minimize redeposition of soil on the garments - known as “graying”. Polishing filters have pore sizes that are extremely fine (3 to 5 microns). They are installed downstream of the main filter system. There are two types of polishing filter mediums - resin-bonded fibers and a spiral cotton element.

Powder Filtration System - Drycleaning filtration systems that utilize filter powder (diatomite) and sometimes filter powder plus activated carbon as a filtering medium. These systems can be either Constant Pressure Filters, or Regenerative Filters.

Pre-charged Solvent - Drycleaning solvent that contains detergent added by the manufacturer. It has been used largely in coin-operated drycleaning machines.

Pre-cleaning - See Spotting.

Precoat - Filter powder applied to the tube filters or filter mesh.

Precoating - Placing a thin layer of filter powder on the filtering medium (screen, tube disc) before any impure solvent has passed through the screen holes. Precoating prevents the clogging of the holes by providing an immediate layer of filter powder as the first impurities come through.

Pre-Lint Filter - A simple filter housing designed to extend cartridge life by pre-filtering lint and dirt from solvent by utilizing reusable or disposable lint bags.

Pre-spotting - See Spotting.

Pump Strainer - A device located in front of the solvent pump in a drycleaning machine that prevents lint and other objects from entering the pump.


Reclamation Efficiency - A measure of the efficiency of the reclaiming dryer or drying cycle in extracting solvent from the clothing. Also known as Drying Efficiency.

Reclaimer - A machine used to remove solvent from clothing by tumbling them in a heated air stream. The solvent vapors are then condensed and routed to a water separator, where the solvent is separated from the water. Also known as a Reclaiming Dryer or Recovery Dryer.

Reclaiming Cycle - The first stage in the drying or reclaiming process, in which solvent remaining in the garments is vaporized by a stream of hot air. The vapors are then condensed and the liquid solvent drawn off and stored for reuse.

Reclaiming or Recovery Dryer - See Reclaimer.

Recovery Unit - See Reclaimer.

Recycle - A process of preparing a solvent for re-use. In drycleaning, this is done by filtering and distilling the drycleaning solvent after it has removed the soil from the clothes. Solvent can be recycled repeatedly by a drycleaner.

Redeposition - The return of insoluble soil to the fabrics from which it was freed during the cleaning cycle. dispersal and redeposition of insoluble soils is the principal cause of “graying”.

Reducing Bleach - A bleach that decolorizes stained or soiled areas through a reducing reaction. Examples of reducing bleaches are: sodium bisulfite, sodium hydrosulfite and titanium stripper.

Refrigerated Condenser - A vapor recovery system into which an air-solvent gas-vapor stream is routed and the solvent is condensed by cooling the gas-vapor stream. Refrigerated condensers recover solvent emissions by chilling the air stream below the solvent’s dew point, causing the solvent and water vapor to condense. Refrigerated condensers can be placed either in the air stream near the end of the drying cycle or at the final exhaust point of the process. In transfer machines equipped with refrigerated condensers, the air stream received from the washer when the door is opened is typically vented to the atmosphere after one pass through the condenser. Thirty percent of the solvent is typically recovered. Vapors from the drying unit are continually routed back to the dryer after passing through the condenser until the drying cycle ends. Eighty-five percent of the remaining solvent is typically recovered. Un-recovered vapors are vented to the atmosphere when the dryer is opened. In vented, dry-to-dry machines equipped with refrigerated condenser, emissions occur when the door is opened. No-vent or closed-loop machines do not vent to the atmosphere and have the highest efficiency in recovering emissions. Also known as a Chiller.

Refrigerated Condenser Coil - The coil containing the chilled gas (usually CFC 11 or CFC 12) used to cool and condense the solvent.

Regenerative Filters - The most widely used type of powder filtration system. It consists of flexible tubes that are constructed of braided metal wire, metal helical springs or braided knit fibers. The filter powder, which is the filter media, is held by the flexible tubes. Spent powder is removed or “bumped” and then the regenerated or pre-coated each day or after each load has been run. Also known as Flexible Tube Filters or Bump Action Filters.

Rigid Tube Filter - A type of non-regenerative filter in which the precoat is supported on an internal wire frame surrounded by a filter screen. Backwashing is used to remove the filter cake from these filters.

Room Enclosure - Stationary structure that encloses a transfer machine system. These enclosures are designed to contain solvent vapors which are vented to a carbon adsorber or an equivalent control device during operation on the transfer machine system.

Rynex - Glycol ether based drycleaning solvent offered as an alternative to chlorinated solvents and petroleum-based drycleaning solvents. Rynex reportedly has a flash point of 203° F.


Screen Filters - Fine mesh screen held in a vertical plane with nipples that feed into a manifold. Screen Filters are used in powder filtration systems. The solvent surrounds the screens where the powder collects and strains insolubles out as the solvent flows through and into the manifold and out. A variation of this type of filter employs a series of horizontal circular screens between each of which is a brush which automatically rotates for cleaning . This filter operates with a blend of sweetener powder and carbon and is automatic in its dispensing of powders and self cleaning. Very few screen filters are in use today.

Second Generation Drycleaning Machine - See Vented Dry-to-Dry Machine.

Separator Water - Wastewater generated from the physical separation of drycleaning solvent and water in a water separator. Separator water is a contact water and therefore contains solvent.

Sizing - A glaze or filler agent used to treat fabrics. Starch is an example of sizing.

Sludge - See Still Bottoms.

Sniffer - See Carbon Absorber.

Sodium Bisulfite - A reducing bleach used in pre-cleaning and spotting operations. Its main use is in removing the last traces of chlorine bleach.

Sodium Hydrosulfite - A reducing bleach used in pre-cleaning and spotting operations.

Sodium Hypochlorite - The most commonly used oxidizing bleach. It is normally packaged as a 5% solution but is used in pre-cleaning and spotting operations in a 1% solution. Sodium Hypochlorite is also widely used in conventional laundry operations.

Sodium Perborate - A common oxidizing bleach used in pre-cleaning and spotting operations . It is a highly alkaline substance and is normally neutralized with acetic acid after application.

SOLVATION Process - A solvent vapor recovery process in which an air stream is continuously circulated through the drycleaning machines condenser, a water bath and the hot clothes in the machine’s tumbler. When passing through the water bath, the air stream becomes saturated with water. The perc and water in the air stream leaving the stream becomes saturated with water. The perc and water in the air stream leaving the bath form an azeotrope, which has a lower boiling point than perc alone, thereby increasing the ability of the machines standard condenser to recover the solvent vapor.

Solvent Mileage - The amount of fabric cleaned per a quantity of solvent; a measure of the efficiency of a drycleaning system. Also known as Solvent Consumption.

Solvent Pump - A pump located in the drycleaning machine that circulates solvent in the machine.

Solvent Relative Humidity - The moisture content of drycleaning solvent with added detergent is expressed as a percentage of the amount of water carried by the detergent in the solvent compared with the maximum amount of water which the detergent in the solvent will carry.

Solvent Relative Humidity Instrument - A moisture control device that collects solvent, air, and moisture vapors from the wash wheel, passes them over a sensing element that measures solvent relative humidity, and automatically injects water in the washer when the relative humidity drops below a pre-determined setting.

Solvent Turnover - Total gallons of distilled solvent that must be replaced to the system for each 100 pounds of fabric cleaned.

Spin Disk Filter - A device containing 36 fifteen-inch diameter disks of polyester fine mesh material mounted on a hollow central shaft with a motor drive to spin the shaft. Solvent enters the center housing through the hollow central shaft. The filter can utilize either filter powder or to be powderless. Also known as a Centrifugal Disc Filter.

Spot Bleaching - The use of a bleach in pre-cleaning or spotting operations.

Spotting or Pre-spotting - The selective application of chemicals, steam, detergent and/or water to loosen or remove specific stains from soiled garments. Spotting is sometimes done prior to drycleaning (pre-spotting or pre-cleaning) but may also be necessary following drycleaning to remove stubborn stains. Also known as Pre-cleaning.

Spotting Board - A work surface for pre-cleaning and spotting work. The spotting board is normally supplied with steam, compressed air and water.

Spotting Agent - A chemical used to clean or bleach stained or heavily soiled areas on clothing. Spotting agents are generally divided into three classifications: dry-side agents (used to clean non-water soluble stains or soiled areas), wet-side agents for water soluble stains or soils, and bleaches which oxidize or reduce stains or soiled areas.

Standard Cartridge Filter - A cartridge filter (carbon core, all carbon or carbonless) that has dimensions of 7 5/8 inches by 14 1/4 inches.

Steam Cabinet - See Drying Cabinet.

Steam Press - A machine used in the finishing process that utilizes steam to press clothing after it has been drycleaned. A steam line from the boiler supplies steam to the press. The garment is held in place on the press by means of a partial vacuum generated by a vacuum unit. The garment is pressed by lowering the press on the garment and pressing a foot pedal that releases the steam. The condensed steam is evacuated by the vacuum unit. See Grid-Head Press and Hot-Head Press.

Steam Stripping - A method to extract additional solvent from distillation residues during the distillation process. In this method, steam is injected directly into the distillation residues in the still. This causes the boiling point to drop and the distillation rate to increase.

Steam Sweeping - A technique used during the final stage of still boil down to recover as much solvent as possible. In this technique, live steam is swept across the still just above the liquid residue. This results in a temperature increase and a resulting additional recovery of solvent.

Still - A device used to volatilize and recover solvent from contaminated solvent.

Still Bottoms - The waste sludge or solid residue from the still. Still bottoms contain solvent, water, soils, carbon and other non-volatile residues. Still bottoms from chlorinated solvent drycleaning operations are hazardous wastes. Also known as Distillation Bottoms, Distillation Residues, Still Residues or Sludge.

Still Kettle - The vessel in which the distillation process occurs.

Still Residues - See Still Bottoms.

Stoddard Solvent - A petroleum drycleaning solvent which is a blend of petroleum distillate fractions (C7 - C12). It is composed of 30 - 50% straight and branched chain alkanes, 30 - 40% cycloalkanes, and 10 - 20% alkyl aromatic hydrocarbons.

Swale - Uneven deposit of non-volatile material on a garment. Also known as Streaks.

Sweetener Powder - A type of filter powder that is composed of activated clay. These clays are adsorptive and will remove soluble impurities from solvent such as detergents, fatty acids and dyes. This powder has been used with filter powder to avoid filter clogging.


TCA - See 1,1,1-Trichloroethane.

TCE - See Trichloroethylene.

Temporary Vapor Storage (TVS) - An emission reduction technology which provides for efficient, economic recovery and temporary storage of perchloroethylene vapors using a high capacity polymeric adsorbent.

Tetrachloroethylene or Tetrachloroethene - See Perchloroethylene.

Tetrachloromethane - See Carbon Tetrachloride.

Third Generation Drycleaning Machine - A closed-loop (dry-to-dry) drycleaning machine equipped with a refrigerated condenser.

Titanium Stripper - A common reducing bleach used on dye stains and to make whites whiter. The active ingredients are titanous sulfate (10 - 15%) and 1 - 4% sulfuric acid.

Transfer Machine - Drycleaning system in which the washing and drying operations take place in two separate units. Some transfer operations have employed three machines: a machine where the clothing is washed; an extractor, where the solvent is extracted from the clothing by centrifugal force; and a dryer (tumbler or reclaimer). Also known as a Cold Machine or a First Generation Drycleaning Machine.

1,1,1-Trichloroethane (TCA) - A chlorinated solvent that was used to a limited extent as a drycleaning solvent (particularly in leather cleaning operations) and was a common dry-side spotting agent. There were problems with equipment corrosion in TCA drycleaning operations.

Trichloroethylene or Trichloroethene (TCE) - A chlorinated solvent that has been used as a both a drycleaning solvent and a dry-side spotting agent. One problem with TCE is that is causes bleeding of many acetate dyes.

Tubular Filter - A cylindrically shaped, fine-mesh screen supported internally by a coiled wire. These elements are hung vertically from a manifold inside the filter. Solvent flows inward through the walls of the elements, then upward. These elements often are coated with a precoat of powder filter to prevent clogging and maintain proper cake porosity.

Tumbler - A dryer in a transfer operation that vents dryer vapors to the atmosphere. Also known as Non-recovery Unit or Tumbling Unit.

Two Bath System - A system in which garments are first run through a solvent/detergent wash cycle and then, to remove residual detergent and soils, through a relatively pure solvent “rinse” cycle.


Vacuum Still - A device that enables drycleaners to distill petroleum-based solvent safely. In this system, air must be pumped out of the still to create a 26-28 inch vacuum, permitting petroleum solvents to be distilled at reduced temperatures (approximately 100° F) and within safe limits.

Vacuum Unit - A device that generates a partial vacuum (through the use of a vacuum pump) for use in steam pressing and spotting and pre-cleaning operations. The condensed steam from steam pressing operations (known as vacuum water) is collected in a tank located at the base of the vacuum unit.

Vacuum Water - Wastewater collected through a vacuum line. This wastewater is generated in pre-cleaning, spotting and steam pressing operations. It is contact water and is contaminated with solvent and spotting agents. Vacuum water collected from steam pressing operations is also known as Press Return Water.

Valclene - A Chlorofluorocarbon drycleaning solvent developed by DuPont in the 1960s. Also known as 1,1,2-Trichlorotrifluoroethane, 1,1,2-Trichloro-1,2,2-trifluoroethane, Freon 113, Fluorocarbon 113, CFC 113.

Vapor Absorber - See Carbon Absorber.

Vapor Recovery Unit - A device used to trap solvent vapors. The vapor recovery unit can recover perc for reuse from vents of a vented dry-to-dry machine, from a dryer of a transfer machine, or from ventilation vents in the workplace. See Refrigerated Condenser, Carbon Absorber, SOLVATION, and Temporary Vapor Storage.

Vapor Absorber - See Carbon Absorber.

Vented Dry-to-Dry Machine - A refrigerated condensation unit from which all the exhaust vapors are vented to the atmosphere when the drycleaning machine door is opened at the end of the drying cycle. With a vented system, about 85 percent control of solvent vapors is achieved compared to an uncontrolled machine. Also known as a Second Generation Drycleaning Machine.

Vented Refrigerated Condenser - A refrigerated condensation unit that vents exhaust vapors to the atmosphere from the cylinder when the machine door is opened at the end of the drying cycle.

Ventless Refrigerated Condenser - A refrigerated condensation unit which does not vent vapors to the atmosphere.


Washer (drycleaning) - A machine used to clean clothing by immersing and agitating them in solvent.

Washer-Extractor - The heart of the drycleaning machine. It contains a horizontal, perforated drum or cylinder that rotates within an outer shell. The shell holds the solvent while rotating drum holds the garment load. The machine first washes the garments then extracts the solvent by rotating at high speed. In a “hot” or dry-to-dry machine, the washer-extractor also serves as the reclaiming dryer.

Water Separator - A device that utilizes gravity to physically separate water that has become mixed with the drycleaning solvent. Water separators are found on stills, dryers, muck cookers and vapor recovery units. They prevent the water from returning with the solvent to the solvent storage tank.

Water Soluble Soil - Soil which dissolves in water. Such substances include: sugar, starch, gums, salt, flavoring agents and syrups, as well as a variety of substances found in foods and beverages.

Wet-cleaning - A professional cleaning technique that uses detergents and water. Specialized machines are used that can be programmed to control such variables as mechanical action, water drying temperature, moisture levels in the dryer and water and detergent volume.

Wet-side Spotting Agent - A pre-cleaning or spotting chemical used on water soluble stains or soils. 

Wheel - The cylinder rotating drum or tumbler within the washer-extractor of a drycleaning machine. 

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