What is the function of a fusible plug in a refrigerant cylinder?

The function of a fusible plug in a refrigerant cylinder is to provide a safety relief mechanism that prevents the cylinder from rupturing due to excessive pressure caused by overheating. The fusible plug is a small, threaded plug made of a metal alloy that melts at a specific temperature. If the refrigerant cylinder is exposed to high temperatures, such as in a fire, the pressure inside the cylinder will increase. When the pressure reaches a critical level, the fusible plug will melt, allowing the refrigerant to vent out of the cylinder in a controlled manner. This prevents the cylinder from exploding, which could cause serious injury or property damage. The fusible plug is a one-time-use device and must be replaced after it has melted. For example, if a refrigerant cylinder is left in direct sunlight on a hot day, the pressure inside the cylinder could increase significantly. If the pressure reaches the fusible plug's melting point, the plug will melt, releasing the refrigerant and preventing the cylinder from rupturing. The fusible plug is a critical safety feature that protects against over-pressurization of refrigerant cylinders.