What is the purpose of a fusible plug in a gas cylinder?

The purpose of a fusible plug in a gas cylinder is to release gas in case of overheating. This safety feature is designed to prevent the risk of a catastrophic failure if the cylinder becomes excessively hot, such as in a fire or extreme high-temperature situation. The fusible plug is made from a material that melts at a specific temperature, allowing gas to escape safely rather than increasing pressure to dangerous levels within the cylinder. This mechanism helps mitigate potential hazards, making it a vital aspect of gas storage safety.

Other options do not align with the primary function of a fusible plug. Rapid filling is more related to valve design and fittings rather than the function of the fusible plug. Preventing rust and corrosion typically involves coatings or treatments of the cylinder material itself. Measuring the gas level is usually accomplished using gauges or indicators and is not related to the fusible plug's purpose. Each of these functions serves a different role in the safe handling and operation of gas cylinders.