3003 W CASINO RD BLDG 45-03 2019-01-28

' November 29, 2018 at a worst case factor of 1.6). These two factors combined are a 4.8 factor that was rounded to 5. Range of building conditions The primary building conditions affecting hazardous area boundaries are ventilation rate and local velocities. Both of these conditions are determined during the test and balance of the ventilation system for the paint mode. The process ventilation system measures and controls airflow continuously on a zone by zone basis. The paint hangar control system terminates paint application capability when the process ventilation rate drops below 75% of design. 75% of design airflow was the condition used for establishing the hazardous area boundaries. The CFD analysis includes the proposed revisions to the building geometry associated with the current project. Any future revisions to the building geometry that would affect airflow in the paint hangar will need to be reviewed for impact on hazardous area boundaries. Range of process conditions The range of conditions that can exist during the process includes different locations of paint application, variations in paint chemistry, and variations in paint equipment. The CFD analysis scenarios are based on experience in the hangar to select the worst case combinations. Multiple scenarios were evaluated, but a critical scenario has 10 painters simultaneously applying paint at locations selected for maximum %LEL concentrations at the boundaries of interest. The CFD analysis does not include all potential scenarios, but does give insight throughout the paint hangar with high resolution for each scenario evaluated. The resolution that CFD provides enables identification of hazardous area boundaries that reflect the actual conditions in the paint hangar with greater precision. By contrast, testing allows the process to go through the normal variations in equipment, paint chemistry, and painter technique, but takes gas samples at a limited amount of locations that must be free of overspray. Comparing previous test data taken in paint hangars with the CFD analysis indicates the CFD analysis is conservative (estimates higher %LEL than expected based on previous test data). This improves confidence in the CFD analysis. Nonetheless, a conservative %LEL value was selected (10%) to account for the potential range of conditions with an additional distance of 2.5 feet to account for plume dispersion from spray guns. The net effect of the CFD accuracy and the range of conditions results in the 2% LEL threshold predicted by the CFD analysis plus 2.5 feet as the critical boundary for the Class I Division 1 boundary when the paint hangar ventilation is at 75% of design flow rate. Page 7 of 1