Abstract: A valve arrangement having a disc which is tapered in cross section from the center to the periphery so that upon impact closure with the seat, deformation of the disc will absorb impact energy. The valve arrangement can consist of two check valves in back-to-back relation, the valve discs being swingable relative to the seats therefor, one of the valves being held in an open position and released upon abnormal conditions so that it can close.

Abstract: A general anesthesia rebreathing system comprised of a disposable portion adapted to be easily coupled to and decoupled from a permanent portion. The system is designed so as to minimize the structural complexity and cost of the disposable portion while assuring that the disposable portion includes all elements which are likely to contaminate gases inhaled by a patient. The disposable portion includes conventional breathing tubing for coupling a source of fresh gas, as from an anesthesia machine, to a patient and in addition an overflow tube for coupling the patient end of the system to an overflow (pop-off) valve, preferably mounted on the machine and constituting part of the permanent portion. The overflow tube entrance is located close to the patient end of the system and in communication with the tubing which conveys expired gas to a reservoir, such as a conventional breathing bag, mounted at the machine end.