Exposure modeling is a valuable tool for assessing chemical vapor exposures that occur during transient events such as small spills of volatile liquids. Models are available to estimate liquid evaporation rates and resulting air concentrations. However, liquid evaporation rate models require the surface area of the puddle in order to provide vapor generation rates in terms of mass per time. This study developed an approach to model the surface area of small spills of pure liquids. A theoretical equation exists relating puddle depth to a liquid’s surface tension, density, and contact angle. A contact angle is a characteristic of liquid-solid interactions at the edge of a puddle. If the depth of a puddle can be calculated and the volume of the liquid spilled is known, the surface area of the puddle can be determined. Values for density and surface tension are published. Contact angles, however, are not readily available. Five hundred and eighty experimental spills were conducted using acetone, ethanol and water. The effective contact angle for each spill was determined. Spill volumes varied from 1.0–30.0 mL. The height of the liquid release varied from 0–15 cm onto a variety of surfaces. The effective contact angle of a puddle was most strongly associated with the liquid’s polarity. The height of the liquid release and type of surface had significant, but smaller effects on the puddle size. The effective contact angle of a puddle from a spill can be estimated as ln(ϴ_eff) = 3.73 – 1.17 · ¹χ^υ/f – 0.06 · h + S. In this equation, ¹χ^υ/f is the polarity index of the liquid, h is the height of liquid release (cm), and S is a surface constant. ϴ_eff can be used with the liquid density, surface tension and volume to calculate the surface area of the puddle. The surface area of the puddle can then be used in evaporation rate models to determine a vapor generation rate for input to vapor concentration models.

暴露建模是评估瞬态事件（例如少量挥发性液体溢出）期间发生的化学蒸汽暴露的宝贵工具。可使用模型来估计液体的蒸发速率和所产生的空气浓度。但是，液体蒸发速率模型需要水坑的表面积，以提供单位时间质量的蒸汽生成速率。这项研究开发出一种方法来模拟少量纯液体溢出的表面积。存在一个理论方程，将水坑深度与液体的表面张力，密度和接触角相关联。接触角是水坑边缘处的液-固相互作用的特征。如果可以计算出水坑的深度并且已知溢出的液体量，则可以确定水坑的表面积。公布了密度和表面张力的值。但是，接触角并不容易获得。使用丙酮，乙醇和水进行了580次实验性泄漏。确定每次溢出的有效接触角。溢出量在1.0–30.0 mL之间。液体释放在各种表面上的高度从0-15厘米不等。水坑的有效接触角与液体的极性密切相关。液体释放的高度和表面类型有明显影响，但对水坑尺寸的影响较小。溢油坑的有效接触角可以估计为ln（ϴ 确定每次溢出的有效接触角。溢出量在1.0–30.0 mL之间。液体释放在各种表面上的高度从0-15厘米不等。水坑的有效接触角与液体的极性密切相关。液体释放的高度和表面类型有明显影响，但对水坑尺寸的影响较小。溢油坑的有效接触角可以估计为ln（ϴ 确定每次溢出的有效接触角。溢出量在1.0–30.0 mL之间。液体释放在各种表面上的高度从0-15厘米不等。水坑的有效接触角与液体的极性密切相关。液体释放的高度和表面类型有明显影响，但对水坑尺寸的影响较小。溢油坑的有效接触角可以估计为ln（ϴ_EFF）= 3.73 - 1.17· ¹ χ ^υ / ˚F - 0.06·H + S。在这个等式中，¹ χ ^υ / ˚F是液体，H的极性指数为液体释放（厘米）的高度，S是表面常数。Θ _EFF可以与液体的密度，表面张力和体积用于计算熔池的表面积。然后可以在蒸发速率模型中使用水坑的表面积来确定蒸汽生成速率，以输入到蒸汽浓度模型中。