The application of a pressure sensing system provides precise closed-loop control and a continuous monitoring of the laboratory differential pressure. The closed-loop feature compensates for a laboratory door being left open, and the monitoring capability notifies operators of the open door. However, the pressure sensing system may have a slower overall response time than other methods of laboratory pressure control. In addition, the quantity of actual supply and exhaust air is not known with this system; knowing this information could provide increased laboratory safety. [Coogan, 1996] [DeLuga, 1995; Laboratory Control and Safety Solutions Application Guide, 1994; Hitchings, 1994]
