Anesthesia machine with modular flowmeters

Abstract

An anesthesia machine is disclosed wherein flowmeters used to denote flow of O.sub.2 and other gases are in the form of precalibrated modules. The modules each contain a flowtube, float and scale and are precalibrated and the modules sealed to prevent tampering or affecting the calibration. The flowmeter modules are thus readily inserted into or removed from the anesthesia machine by a single plug-in maneuver to a common manifold without further calibration or leak testing. A key index system prevents the mislocation of any particular flowmeter module in a machine. The flowmeter module has a lower manifold at its bottom where all plug-in connections are located. A flowtube containing the float extends upwardly from the manifold and has an easily visible scale for accurate readings. Internal tubing within the flowmeter module returns gas from the flowtube back to the outlet connection in the lower manifold. The flowmeter modules may be, therefore, completely tested for leaks, calibrated at the source and tamperproof measures included to prevent disassembly or in any way upsetting the calibration short of factory rebuilding the flowmeter module. Because the units are factory sealed, replacement of flowmeter modules may be made by personnel in the field unskilled with such machines.