When transporting or storing containers, what is necessary to use?

Using a POL plug or dust cap is essential when transporting or storing containers, particularly those that hold gases like propane or other pressurized liquids. This measure helps ensure that the contents of the container remain secure and that there is no leakage or contamination during transport or while in storage. The POL (Pipeline and Offshore International) plug provides a tight seal on the valve, preventing any unintended release of the gas, which could pose safety risks.

The inclusion of a dust cap further protects the valve from dirt and debris, which could interfere with the proper functioning of the container or compromise safety. Employing these caps is a standard practice in maintaining the integrity and safety of storage and transport operations for gas cylinders and similar containers.

Other options may have their applications in specific situations, but they do not address the primary concerns of leakage and contamination as effectively as a POL plug or dust cap does.