Which type of vehicle tank metering system does NOT require a zero set back interlock?

The selection of vehicle-mounted metering systems as the correct answer stems from their operational characteristics and design standards. Vehicle-mounted metering systems are typically designed to provide a streamlined approach for mobile fuel delivery, wherein the system can self-contain the metering process. This design often incorporates advanced calibration systems that negate the need for a zero set back interlock, making them efficient for quick and precise fuel dispensing without requiring manual zeroing each time fuel is delivered.

In contrast, mobile metering systems, retail distribution systems, and home heating oil delivery systems often necessitate additional checks and balances, such as a zero set back interlock, to ensure the accuracy and integrity of the measurements prior to dispensing fuel. These interlocks serve as safeguards against potential errors that can occur during operation, which is crucial in scenarios involving varying heights, manual handling, or less regulated environments. Vehicle-mounted systems, however, integrate features that handle these variables inherently, allowing them to operate effectively without the additional requirement for a zero set back interlock.