Abstract: A volume sensing system includes electronic circuitry which is electrically connected to an ultrasonic transducer. The transducer is affixed by means of an adaptor to the base of a container having a known configuration. The container holds a liquid and a gas so that a liquid-gas boundary is formed within the container. The transducer generates ultrasonic pulses which propagate through the liquid, are reflected at the liquid-gas boundary, and are received again by the transducer. The received return pulse is converted into an electrical signal which is analyzed by the electronic circuitry to determine the level of the liquid within the container. The level of the liquid within the container is then employed to determine the volume of the liquid within the container in accordance with the configuration of the container. In a preferred embodiment, the adaptor includes an indicator which may be used to identify the configuration of the container.

Abstract: Disclosed is a vacuum regulator apparatus such as for automatically establishing and maintaining a predetermined vacuum for withdrawing fluid from a chest cavity. The apparatus comprises a water manometer or vacuum regulator portion and a water seal portion. Atmospheric air is vented into the vacuum line through the vacuum regulator portion by displacing a predetermined height column of a fluid such as water. A filter is disclosed for preventing the escape of water from the manometer portion of the apparatus into the downstream vacuum source. A second filter is disclosed for permitting two way gas flow at the upstream end of the manometer portion, but for substantially preventing fluid flow in an upstream direction out of the manometer. Fluid fill ports are disclosed on the manometer and water seal portions for permitting infusion of water to precise and repeatable column heights.