APPENDIX A5$_{ }$ applied to propylene glycol, which is somewhat less volatile than ethylene glycol.  These  emission factors are also embedded into FAA’s EDMS/AEDT.  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 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.  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.  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.  41$_{ }$ Equation A5-14. Hydrocarbon Emission for Solvent Degreasers  A5.3.5.1  Methodology  A5.3.5  Solvent Degreasing  E$_{VOC }$= D x (QC - QD)  Where:  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.  D = density of solvent, expressed as pounds per gallon. 