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applied to propylene glycol, which is somewhat less volatile than ethylene glycol. These emission factors are also embedded into FAA’s EDMS/AEDT. 

## A5.3.5 Solvent Degreasing 

Solvent degreasing units are regularly used for aircraft and ground vehicle maintenance, paint stripping and other miscellaneous activities utilizing organic solvents. Solvent degreasers use organic solvents to remove fats, oils, grease, wax or soil from various metal, glass or plastic items. There are two types of solvent degreasers commonly used: cold cleaning and open -top vapor degreasers. Cold cleaning operations use alcohol, ketones and petroleum distillates as solvents for parts cleaning through immersion, brushing, spraying or flushing. Ope n-top vapor systems are boiling degreasers that clean by the condensation of solvent on the surface of parts being cleaned. Each of these operations causes VOC emissions due to evaporation of the solvent. 

## A5.3.5.1 Methodology 

The use of organic solvents such as chlorinated hydrocarbons, petroleum distillates, ketones and alcohol results in the evaporation of VOC, which are subsequently either disposed of as waste liquids or released to the atmosphere. If water -based alkaline wash systems are used degreasing, no evaporation of VOC occurs. 

The methodology for estimating evaporative VOC emissions from the operation of solvent degreasers is based on the assumption that all solvent consumed by a solvent degreasing unit is either disposed of as waste liquid or released to the atmosphere as VOC emissions. emissions to the atmosphere, therefore are estimated by calculating the difference between the volume of solvent consumed and the volume of solvent disposed as liquid, and multiplying this difference by the density of the solvent. This methodology is expressed by Equation A5-14 ( Hydrocarbon Emission for Solvent Degreasers ) which computes the VOC emission for one solvent degreaser. 

Where: 

<img src='content_image/517529.jpg'>

E$_{VOC }$= hydrocarbon emissions from solvent degreasing unit, expressed in pounds. 

QC = quantity of solvent consumed in solvent degreaser in a given time period, expressed as gallons. 

QD = quantity of solvent disposed of as liquid in given time period, expressed as gallons. 

## Equation A5-14. Hydrocarbon Emission for Solvent Degreasers 

D = density of solvent, expressed as pounds per gallon. 

The quantity of solvent consumed and disposed of ( expressed in gallons) should be available from the operator of the solvent degreaser. If no records on solvent disposal are available, then it should be assumed that 100 percent of the solvent consumed by the solvent degreaser is released to the atmosphere as VOC emissions. The density of solvent, expressed as pounds per gallon , should also be available from the operator of the solvent degreaser or the solvent manufacturer. If this information is unavailable the values listed in Table A5-9 ( Specific Gravity of Common Degreasing Solvents ) may be used. 

