GB908974A - Improvements in valves - Google Patents

Abstract

908,974. Respiratory appliances. BLEASE ANAESTHETIC EQUIPMENT Ltd. July 19, 1961 [July 19, 1960], No. 25166/60. Class 81 (2). In anaesthetic or forced breathing apparatus the inhalation and exhalation valves are biased to the closed and open positions respectively and the bias is overcome by the cyclic application of gas supply pressure. The system is actuated by two bellows 2, 4, the first of which is smaller than the latter so as to operate at a higher pressure. This bellows 2 is inflated from a gas supply, against a loading spring 14 until it actuates an electrical contact 20 which opens a valve 10 to allow the gas to pass into and inflate bellows 4 which continues until a contact member 24 engages a switch 26 and again closes the valve 10. During this time the inhalation valve 32 is held closed, by an adjustable compression spring 44, and the exhalation valve 34 is held open by a tension spring 66, which holds the diaphragm 58 clear of the seating 56, so that the patient, at 52, exhales freely through a valve 62 or into a breathing bag 64. The closure of valve 10 during this period allows the pressure to be gradually built up in bellows 2 and this is communicated by pipe 68 to the valve 34 where by bearing on diaphragm 58, it ultimately overcomes the bias of spring 66 and closes the valve. Subsequently, also, as the pressure continues to rise, it bears on the diaphragm 42 until it overcomes the spring 44 and opens the inhalation valve, whereupon the bellows 4, under the influence of a weight 18, forces its contents into the patient's lungs. Finally, the completion of the inflation of the bellows 2 again opens the valve 10, whereupon the pressure in the pipes 6, 46, 68 falls to a low value and the system reverts to the exhalation phase. Specification 900,866 is referred to.