3003 W CASINO RD PAINT HANGAR BOUNDARIES 2023-07-20

Geminus Boeing Project Contract No.EVE-16-2929 �L.o Technology Development CEI Project No. 160731 • For the ingredients where a typical mass percentage range was provided, the composition was selected to err on the side of increasing volatile concentration in the paint. This is a conservative assumption because it prevents expected paint mixture variations from creating a mixture with higher volatile concentration. The above assumptions impose the following limitations on the model: • If a paint is used with concentrations of a volatile whose gaseous properties vary significantly(higher) than those used in this model, the % of LEL predictions may be invalid. This is mitigated somewhat by heptan-2-one having one of the lower LEL values of the significant components in the pain spray. If changes to the paint volatiles are anticipated a re-analysis of the results of this study are warranted. 2.2.3.2 Volatile Outgassing of Painting Surface The combustible vapors emitted from the paint after the paint has been applied to aircraft surfaces were not modeled in the CFD simulations. This is due to the long evaporation time for these vapors to evolve from the coating that has already been applied, which is typically on the order of 10 to 20 minutes[21]. The volatiles contained in the overspray droplets, due to their very high surface to volume ratio, were then assumed to immediately evaporate from the over spray cloud upon release from the paint gun. Since the paint gun is remote from the aircraft fuselage and the overspray from the paint gun vaporizes instantly, this case is considered to be the more hazardous case and creates a hazardous boundary that extends further beyond the aircraft fuselage than the vapors evaporating off of the fuselage would. 2.2.3.3 Spray Gun Emission Model And Position The spray gun model was based on Graco Pro Xp85 AS [20]. Position and orientation of the spray gun is shown in Figure 12. The following assumptions were made regarding the spray guns and their positions and were approved by Boeing: • The spray gun is held in a position to mimic an operator leaning over to paint the crown for fuselage and engine locations (-42" from platform surface). • The spray gun is in continuous operation in a fixed position. This is conservative as typically the spray gun is in continuous motion across the aircraft surface and is not always operated continuously. Thus the instantaneous local % of LEL concentrations in practice are likely to be lower than predicted. The above assumptions impose the following limitations on the model: • Spray guns with significantly lower transfer efficiency should not be used or the analysis must be revisited. • Spray guns should not be operated away from the aircraft surfaces for any significant period of time that may produce a local paint cloud that may not be immediately convected away 13