This vaporizer was between services so it was virtually empty. Also, you may notice the flowmeter was turned off at the time I momentarily demonstrated how to turn the dial on the vaporizer, so there was no oxygen flow. It is very unlikely any gas left the vaporizer. We ‘use’ equipment all the time for instruction, so it is never a “waste”. Nevertheless, thank you for your concern.
Source:
http://dogtrainertips.net/ahs-rvtg-program-veterinary-anesthetic-machine/