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A <br /> Gemnus Boeing Project Contract No.EVE-16-2929 <br /> Technologyi Development CEI Project No. 160731 <br /> 2.4 Expected Impact of Modeling Assumptions On % of LEL Predictions <br /> Species At <br /> Volatile Spray Gun %Of Volatiles <br /> TypicalTypical Paint Types: Paint Flow Volatile Composition: Exit: Transferred <br /> Spray Gun Pigmented Paints Rate: Concentration: Heptan-2-one, Paint Inert, To Overspray <br /> &Paint Primer 500 cc/min 35-54% n-butyl Liquid Cloud: <br /> Operation Clear Coat Maximum Acetate,others Volatiles, 20-30% <br /> Atomizing Air <br /> Volatile Species At %Of Volatiles <br /> Selected Composition: Spray Gun <br /> Spray Gun Selected Paint <br /> Volatile Entire Volatile Exit: Transferred <br /> Selected Paint Type: <br /> &Paint Clear Coat Flow Rate: Concentration: Mass Modeled Vaporized To Overspray <br /> CFD Model 500 cc/min 54% As Heptan-2- Volatiles, Cloud: <br /> 40% <br /> one Atomizing Air <br /> Figure 13: Overview of the development calculation process to conservatively calculate <br /> the amount of volatile gaseous components emitted during the clear coat <br /> painting process. <br /> The CFD volatile and spray gun model simulates worst case scenario for volatile <br /> concentration. Volatile modeling is based on conservative selection of parameters: <br /> • Paint type with maximum overspray cloud <br /> • Maximum paint flow rate. <br /> • Maximum volatile concentration. <br /> • Maximum volatile transfer to overspray cloud. <br /> • Volatiles instantly vaporize to gaseous state. <br /> The simplifying assumptions made do not reduce conservative nature of model: <br /> • Heptan-2-one has typical LEL & molar weight of other volatile components. <br /> • Heptan-2-one flow rate is increased to accommodate other volatiles not modeled. <br /> • Inert paint droplets (not included in model) are small and low density and are not <br /> expected to influence bulk motion of overspray cloud. <br /> • Volatile outgassing from painted surface takes place over a long (10-20 min.) <br /> time scale and experience shows that this does not contribute to volatile <br /> concentration. <br /> See Figure 13 for a comparison between typical paint operation and the parameters chosen to <br /> simulate it in CFD. See Table 2 for the limits of volatile concentration in the clear coat and <br /> Table 3 for the primer. The red box represents the maximum volatile concentration, which was <br /> used for the CFD simulation. <br /> 23 <br />