Which component is NOT part of a gas chlorine cylinder?

The correct response indicates that the injector is not a component of a gas chlorine cylinder. A gas chlorine cylinder primarily consists of several key components essential for its safe and effective operation. These components include a packing nut, which secures the valve and prevents leaks; a fusible plug, which serves as a safety feature designed to melt and relieve pressure at high temperatures; and a valve packing gland, which helps to ensure a tight seal around the valve stem.

The injector, however, is not part of the cylinder itself. Instead, it is a separate device used in conjunction with the chlorine cylinder for the purpose of introducing chlorine gas into a water system. This means that while the injector plays a crucial role in the application of chlorine, it does not physically reside within the gas chlorine cylinder, making it the correct choice as the component not part of the cylinder itself.