Abstract: A dry type discharge liquid extraction apparatus is provided with a fluid collection chamber, a coupling for introducing a vacuum into the fluid collection chamber, and a pressure control valve for regulating the flow of air from the collection chamber to the coupling. Also provided is a one-way check valve between the fluid collection chamber and the pressure control valve and a vacuum pressure stabilizing valve which is vented to atmosphere and interposed between the pressure control valve and the coupling for selectively passing air at atmospheric pressure to stabilize the introduced vacuum.