Bourdon Pressure Gauge
Date of manufacture:
A cylinder pressure gauge from an anaesthetic machine. The back of the gauge has been removed to reveal the sensing mechanism. The curved oval tube tends to straighten when pressure is applied to its lumen. The resulting deflection, proportional to pressure, is amplified by the mechanism and turns the spindle of the indicator dial.The hair spring takes up any slack in the linkage.
The gauge was patented in France by Eugene Bourdon in 1849. It is tolerant of high (cylinder) pressures, is linear and generally reliable. Substantial over-pressure can cause it to develop an offset error. The majority of problems arise from loosening of the needle on the meter spindle. See the example which is sensing atmospheric pressure. The gauge has received a knock as the plastics lens is broken.The 'use no oil' label is included because both nitrous oxide and oxygen are associated with a combustion hazard.
Pressure regulators and gauges