WRIGHT'S RESPIROMETER

A gas volume meter for use in the breathing circuit of an anaesthetic machine or ventilator which works by directing the breathing gases through oblique slots in a small cylinder enclosing a small vane which is made to rotate. The spindle on which the vane is mounted drives a gear train connected to a pointer which moves over a dial indicating the volume of gas passed. Gases which flow back through the device do not register since they enter along the axis of the vane spindle. A key feature of the Wright's respirometer is a mercurial seal between the measuring chamber and the gear train which prevents moisture penetrating the mechanism. It has controls to lock the mechanism and to reset the pointer to zero. The dial has an additional scale driven by a further gear so that accumulated gas flow is indicated. Some errors occur at high and low flows but these tend to cancel out under respiratory flow patterns. The Drager volumeter is somewhat similar.

Content and Design Copyright 2000 Dr. Malcolm C Brown.  See Title Page for more details