What should a vapor service valve (POL) be equipped with when it is disconnected?

A vapor service valve (POL) must be equipped with a cap or plug when it is disconnected to ensure safety and prevent the escape of gas. This practice is crucial as it helps to contain any volatile substances that may be present in the system. Securing the valve with a cap or plug mitigates the risk of hazardous vapor release into the environment, which could lead to potential fire hazards or exposure to toxic gases.

Using a cap or plug also protects the valve from contamination and damage when it is not in use, which is vital for maintaining the integrity and functionality of the equipment. This precaution is standard in safety protocols for handling pressurized containers and gases.

While other options like a safety lock, pressure gauge, or replacement valve may serve important functions in different contexts, they do not specifically address the requirements for disconnecting a vapor service valve in terms of safety and containment.