Importance

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Abstract

A device and method for calibrating pulmonary function testing equipment by discharging a precise volume of compressed gas at reproducible and substantially exponentially diminishing flow rates through an orifice of a selected size into such equipment. The device includes a container defining a chamber for containing a predetermined volume of gas at a preselected pressure, a gas discharge conduit, which may serve as a conversion or expansion chamber, communicating with the container and having a flow-restricting fixed orifice of predetermined size for the discharge of gas, and a mechanism normally preventing the discharge of gas from the device but being selectively operable to release the gas through the orifice at reproducible and substantially exponentially diminishing flow rates into a spirometer for calibrating that instrument. In one form of the invention, there is provided an isolation housing having a pair of chambers, one of which communicates with the gas-discharging device and the other with the remainder of the pulmonary function testing equipment, the chambers of the housing being separated by a flexible barrier which prevents intermixing of the gaseous contents of the respective chambers. One or more heating elements may also be provided so that the air discharged into the pulmonary function testing equipment will be warmed to body temperature.

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First Claim