DESIGN CRITERIA FOR ROOF WASHDOWN SYSTEMnPhase 1. Fallout Removal Studies on Typical Roofing Surfaces for Two Size Ranges of Particles (177-350 n and 350-590 μ)

摘要

Fallout simu2ant particles ranging in size from 177 to 350 and 350 to 590 microns were deposited on selected typical roof sections 48 ft long by 8 ft wide to determine the effect of water flow rate, slope, and sur face type on wash down effectiveness. More than 90% of the stimulant can be removed on composition shingles, aluminum shingles and roll roofing at slopes of 1:12 or steeper with 2 to 3 gallons of water per min per ft of roof width (gpm/ft). It was found that wash down is ineffective on tar and gravel roofing without prior removal of the loose gravel. Wash down on a fiberglass epoxy laminated roof will remove better than 99% of the stimulant particles with a water flow rate as low as 1 gal/min/ft.