Importance

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Abstract

A compact, simplified, totally pneumatic demand valve designed for coupling between a source of pressurized gas and a recipient user is provided which achieves a high degree of sensitivity and flow control without expensive, bulky valving arrangements characteristic of prior demand valves. Preferably, the demand valve includes a valve body presenting a gas flow passageway, together with pneumatically coupled sensing and slave diaphragms; the slave diaphragm is interposed in the flow passageway and prevents gas flow during the exhalation phases of the patient's breathing cycle. During inhalation sensed by the sensing diaphragm, the slave diaphragm is shifted to open the gas flow passageway in the valve, thus permitting passage of gas to the patient. The valve is designed for coupling to a fixed orifice flow controller, which may be positioned either downstream or upstream of the valve as desired.

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First Claim