The effect of the size of openings on contaminant control between two adjacent spaces with differing air pressures.

Maintaining a pressure difference between zones or rooms is an important method of controlling the spread of air contaminants. Where it is well managed, this method will provide better control with less energy consumption, particularly in health care or electronic component manufacturing facilities. However, it is difficult to control a multizone system to maintain a pressure difference when there is an opening between two adjacent zones. To prevent the spread of contaminants into the "clean" zone, it is necessary to maintain some level of pressure difference. This study investigates the effect of changing the opening size between two small rooms and evaluates the contaminant dispersion at varying pressure difference values by using a tracer gas technique. The influence of several parameters, such as air pressure difference, surface area of opening, and supply air volume between two interior zones on contaminant transportation through an opening was investigated. The control pressure differences between two adjacent spaces were arranged from 2.49 to 14.69 Pa. Pressure difference was found to be an effective predictor of contaminant diffusion. An empirical relationship between pressure and opening size is presented between two rooms that will predict contaminant control required levels. The coefficient of determination (R(2)) of this correlation is 0.9226.