What is the primary role of fusible plugs in chlorine cylinders?

The primary role of fusible plugs in chlorine cylinders is to provide safety against overpressure. These plugs are designed to melt at a specific temperature, which is typically reached in the event of a fire or significant heat exposure. When the fusible plug melts, it creates a venting mechanism that allows chlorine gas to escape from the cylinder in a controlled manner rather than allowing the pressure to build up uncontrollably. This prevention of overpressure is crucial, as excessive pressure could lead to catastrophic cylinder failure, potentially causing injury or environmental harm due to the release of toxic chlorine gas. Thus, fusible plugs act as a safety feature, ensuring that the cylinder can relieve pressure safely under extreme conditions.