When dealing with gas cylinders, what is the most reliable indication of what gas is contained within?

The label on the cylinder is the most reliable indication of what gas is contained within. Labels provide specific and critical information about the content, including the type of gas, manufacturer details, and safety information. This is standardized across various gas cylinder manufacturers and ensures consistent identification, which is crucial for safety and proper handling.

While other factors like the color of the cylinder can give some indication about the gas type—often following industry standards—color can sometimes be misleading or inconsistent between different manufacturers or regions. The weight of the cylinder may also vary depending on the gas and its volume, but it is not a definitive indicator of the specific gas contained. Additionally, relying on sound during gas release is not a safe or effective method for identifying gases, as different gases may produce similar sounds or the sound may not reliably indicate the gas type. Therefore, the label is the most accurate and trusted source of information in identifying the contents of a gas cylinder.