When testing a loading rack meter with a maximum marked discharge of 1500 gpm, at what discharge rate must a special test be conducted if the product is diesel fuel?

When conducting a special test on a loading rack meter, the discharge rate required for diesel fuel is crucial to ensure accurate measurement but also to adhere to industry standards regarding meter performance.

In the context of flow measurement, especially in high-capacity systems like loading racks, standard practices often dictate that special tests, such as a verifications check, be performed at a lower flow rate than the maximum capacity of the meter. The specified rate for diesel fuel being 300 gpm aligns with regulatory guidelines and industry standards for flow measurement, which typically suggest testing at a rate that is 20% of the meter’s maximum capacity for accurate verification. Since the maximum marked discharge for the meter in question is 1500 gpm, 300 gpm constitutes exactly 20% of that maximum, thus confirming the necessity for testing at this lower rate to accurately assess the meter's performance under conditions that reflect typical operational scenarios.

This lower discharge rate ensures that the entire range of the meter’s operation is reliable, allowing for effective verification of the meter's calibration and accuracy, particularly when dealing with viscosity and density variations inherent to diesel fuel. The standard practices focus on ensuring that meters maintain their accuracy and reliability across a range of operations, rather than just at full capacity.