What type of delivery service requires a cargo tank operator to remain within 25 feet and have an unobstructed view of the cargo tank?

In the context of NFPA 58, an unmetered delivery service requires the cargo tank operator to stay within 25 feet and maintain an unobstructed view of the cargo tank during the delivery process. This requirement is in place to ensure safety and proper monitoring of the transfer of liquefied petroleum gas (LPG) at all times.

The reason for this requirement is primarily due to the inherent risks associated with the transfer of flammable gases. By keeping the operator close and maintaining a clear view, it allows for immediate response to any potential hazards or emergencies that may arise during the delivery. This safety measure is crucial to prevent leaks, spills, and other incidents that could pose a danger to the operator and the surrounding environment.

In this scenario, options like metered delivery service, emergency delivery service, and scheduled delivery service do not necessitate the same level of proximity and visibility as unmetered delivery service. While they also have safety considerations, the specific stipulation of an unobstructed view within 25 feet uniquely applies to unmetered delivery service as per the NFPA regulations.