GB814427A - Improvements in volatile anaesthetic vaporising apparatus - Google Patents

Abstract

814,427. Respiratory appliances. CYPRANE Ltd. Oct. 18, 1957 [Dec. 24, 1956], No. 39189/56. Class 81 (2). Anaesthetic apparatus using liquid anaesthetic has a by-pass valve by means of which part of the incoming air is made to pass through a vaporizing chamber having a temperaturecontrolled outlet leading to the face-mask. Air enters through a duct, not shown, into a chamber 29 in the body 22 and may then pass around the valve head 26 to a second chamber 24 and so to the outlet 28 leading to the facemask. The valve 26 is, however, mounted on a slidable piston 23, the axial position of which is determined by a spiral groove 38 engaged by a fixed pin 39, and when the head 26 is moved so as to partially obstruct the outlet from the chamber 29 air is deflected through port 31 into the vaporizing chamber 1, containing a series of wicks 13 on perforated metal supports. The outlet 17 from this chamber is controlled by a plate 18 mounted on a temperature-sensitive strip 19 and leads to a port 32, which is now uncovered by an annular recess 34 in the piston 23, allowing communication with a port 35, in the body structure, leading to the exit to the mask. Rotation of the piston 23 opens or closes the exit from the chamber 29, so deflecting a lesser or greater proportion of the air through the chamber 1. When the piston 23 is pressed fully in so that port 32 is closed, a second recess 33 is aligned with the port 31 and vents the chamber 1 to atmosphere through a bore 42.