NL160490C - NARCOSE VAPORIZER. - Google Patents

Abstract

1,221,373. Anaesthetic apparatus. O. H. DRAGER [trading as DRAGERWERK, HEINR. & BERNH. DRAGER], 21 Oct., 1968 [21 Oct., 1967], No. 49924/68. Heading AST. An anaesthetic apparatus comprises a liquid anaesthetic evaporation chamber 9 connected in a first conduit 1, 2, 5, 8, 3, 7 and 13, a bypass conduit 2, 4, 6 and 7 bypassing the chamber and a throttle 4 in the bypass conduit for regulating the relative amounts of carrier gas passing through the bypass and chamber and comprising a valve port 4a and throttling member 4b having a connecting member 23 linked by a pin 25 to spindle extension 21, the extension 21 and member 23 having different coeffiients of expansion so that the throttle is controlled by the temperature of the liquid anaesthetic in the chamber. Spindle 15 and extension 21 pass through the throttling member but are not directly attached to it. Manual adjustment of throttle 4 is by thread 19 and knob 18. The coefficients of expansion of spindle extension 21 and connecting member 23 are chosen so that as the temperature of the liquid anaesthetic falls and the vapour pressure falls consequently, the bypass throttle tends to close so that more carrier gas passes through the chamber and maintains constant the concentration of anaesthetic vapour in the carrier gas emanating from 13. A second throttle 3 may be interposed between the chamber 9 and mixing chamber 7 and connected by meshing gear wheels 16 and 17 to the spindle of throttle 4 so that as 18 is turned to close throttle 4, 3 is opened by the same amount and vice versa. The throttle 4 can be adjusted so that it closes at a predetermined temperature in the chamber 9. The temperature of the liquid anaesthetic can be sensed by a stud 26 and read on a dial 24 or the dial 24 can be calibrated to read the percentage of anaesthetic vapour in the mixture once the temperature has fallen and the carrier gas carries the saturation concentration of vapour at the liquid temperature.