How is the contents of a medical gas tank determined?

Determining the contents of a medical gas tank is most accurately done by reading the pressure gauge. The pressure gauge measures the internal pressure of the gas remaining in the cylinder, which correlates to the volume of gas still available. Each type of medical gas has a specific pressure at which the cylinder becomes empty, so monitoring the gauge allows healthcare professionals to estimate how much gas is left and to determine when a refill or replacement is necessary.

While weighing the cylinder may provide some information, it is not commonly used in clinical settings for this purpose, as different gases can have different densities and weights, which complicates this method. The cylinder's size does not inherently indicate the amount of gas it contains, as the actual volume is dependent upon both the size and pressure. Lastly, checking the expiration date of the gas cylinder does not provide any information about the remaining contents; it merely indicates whether the gas is still safe to use based on manufacturer standards.