If you put a bladder that is filled with air and tied up, into the pipe of a heated stove, the air inside will expand so much as to burst the bladder with a loud report.

A transparent almost pure gelatin prepared from the air bladder of the sturgeon and certain other fishes and used as an adhesive and a clarifying agent.

When filling the system with water, open valves to tank to ensure any water or air remaining in the bladder from factory testing is displaced prior to placing the tank in operation.