A 1.40 Relative Drying Time 1.20 1.00 A Relative Drying Time 1.80 1.60 1.40 0.80 1.20 0.60 65 70 75 Space Dry Bulb (°F) 80 1.00 B 1.40 Relative Drying Time 1.20 1.00 0.80 0.60 55 60 65 70 75 Space Dry Bulb (°F) 80 85 B Relative Drying Time 65 70 75 Space Dry Bulb (°F) 40°F Space Dew Point 45°F Space Dew Point 80 2.00 0.80 1.80 0.60 1.60 1.40 Figure 2a (top): Relative drying time of processes in the bathroom using the thermodynamic wet-bulb temperature as the surface temperature. Figure 2b (bottom): Relative drying time of processes in the bathroom using the thermodynamic wet-bulb temperature plus 50% of wet-bulb depression as the surface temperature. 1.20 1.00 0.80 The more interesting focus of the study was to determine what the maximum length of time is between the initial wetting of the washcloths and the time when their condition was still considered to be “fairly wet” in a space at SBSC. The authorities sent the two washcloths to us that were found at the crime scene resting on a bathtub rim. One of the washcloths had a plaid pattern, which enabled the determination of the width of the rim. An acrylic rim was made to mimic the original rim. After many preliminary tests, a test procedure was refined in which the washcloth was set on the rim and fully wetted (an unrealistic start condition because the usual procedure would be to wring it out before setting it on the rim). The weight of the rim and the washcloth were measured about every two hours for about 24 hours, until which time there was a negligible loss of water. Additionally, the space dry bulb and relative humidity were simultaneously recorded. The plaid washcloth was measured to be about 11 in. by 11.5 in. (279 mm by 292 mm) and weighed 29 grams 26 ASHRAE Journal 0.60 55 60 65 70 75 Space Dry Bulb (°F) 80 85 20°F Dew Point Depression 40°F Dew Point Depression 30°F Dew Point Depression 50°F Dew Point Depression Figure 3a (top): Relative drying time for correcting test data from conditions substantially different from SBSC using the thermodynamic wet-bulb temperature as the surface temperature. Figure 3b (bottom): Relative drying time for correcting test data from conditions substantially different from SBSC using the thermodynamic wet-bulb temperature plus 50% of the wet-bulb depression as the surface temperature. (dry). While the placement of a washcloth on a bathtub rim seems a fairly arbitrary task, the plaid cloth and the police video showed its placement on the bathtub rim provided a means to closely replicate the placement of the washcloth ashrae.org April 2010