Isocyanate exposure, emission and control in small motor vehicle repair premises using spray rooms: Phase 1.

Title	Isocyanate exposure, emission and control in small motor vehicle repair premises using spray rooms: Phase 1.
Free Download	Free pdf download available (1 mb) Click Here to view document.
Author	White, J., Coldwell, M., Davies, T. and others. Health and Safety Laboratory for HSE.
Series Code	RR
Series Number	496
Publisher	HSE BOOKS
Date of Publication	2006
Length	122 pages
Stock Code	RR496
Notes	research report 496. (RR496) (RR 496) WEB VERSION ONLY
Abstract	A mock up spray room was constructed within the HSL spray booth with dimensions, ventilation conditions, extraction rates etc set to represent typical MVR spray room conditions. A robotic sprayer was used to simulate paint spraying of car parts under a range of conditions; including spray orientation relative to the extraction duct, spray gun type, ventilation (air in) set up and extraction rates. Factors affecting the amount of airborne NCO are; gun type (eg HVLP give ~ 2 to 5x lower levels than conventional types), gun condition and set-up, spray pattern and isocyanate formulation. Spraying in the direction of the extract fan did not decrease airborne NCO. Airborne NCO took a significant time (~20+ minutes) to clear the spray room. The majority of air in the spray room was close to perfect mixing (tracer gas experiments) but short-circuiting (ie inlet air that is extracted without mixing with the main body of air in the room) occurred. This agrees with HSL/HSE field observations. Tracer gas studies found that the clearance time was proportional to the air-flow rate. If this is the case for spray rooms in general, then the clearance rate may be estimated by calculation from the perfect mixing equation. The near time monitor (paper tape reader) underestimated significantly (~10x) the amount of airborne NCO but both the real time (photo-ionization detector) and near time monitors (paper tape reader) gave clearance times that were comparable with the HSL standard method. Spraying solvent through the guns to clean them produces high levels of airborne isocyanate (~ thousands of µg NCO/m3) and should not be undertaken unless full control procedures are in place. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the author alone and do not necessarily reflect HSE policy.
Keywords	Research; Isocyanates; MVR; Motor vehicle; Spray rooms; Spray guns; Paint spraying