By Keith Reid

We started a review of best practices to preserve diesel fuel quality in the winter 2022 issue of Fuels Market News Magazine. The article, “Canceling Corrosion,” served as part one of an overview of why diesel fuel quality is so important today. It shared some of the recommendations from the Fuels Institute best practices’ report “Diesel Storage Tanks: Industry Practices to Minimize Degradation and Improve Fuel Quality” aimed at retailers and their fuel storage and dispensing infrastructure. In this second part, we provide an overview of the Fuels Institute report “Diesel Fuel Loading and Delivery: Industry Practices to Minimize Degradation and Improve Fuel Quality” aimed at marketers/wholesalers and reducing contamination concerns between the loading rack and the retail tank.

To summarize the concern, modern Tier 4 high-efficiency diesel engines using high-pressure rail systems are far more demanding and susceptible to damage when it comes to particulate and water contamination. It is important to reduce concerns such as the co-mingling of diesel fuel with other products (such as gasoline) or introducing water into the fuel delivery process. These best practices will help preserve the quality of diesel fuel as part of the routine procedures involved with loading and unloading by tanker and tank truck drivers.


Terminal Loading and Transport

As “Diesel Fuel Loading and Delivery” notes, unless a dedicated tanker or dedicated compartment is used to transport diesel fuel from a terminal to a storage tank, there is a chance the diesel fuel can become contaminated with other products. Therefore, an initial recommendation is to use dedicated tank compartments (with split loading) or dedicated tank trailers for each fuel product. That is often not feasible except in operations where there are sufficient volumes in the individual products to make it worthwhile.

Where more operational flexibility is required, and tanks and compartments must haul varied products like gasoline, they should be as empty as possible and then filled to the maximum capacity with diesel to prevent the retention of gasoline vapors.

A note on split loading: Efforts should be made to minimize the possibility of accidental cross-contamination when dedicated compartments are involved. Also, it’s useful to load the diesel compartment first then the gasoline compartment(s) to avoid gasoline vapor back flowing into the diesel tank.


Diesel Fuel Delivery

As “Diesel Fuel Loading and Delivery” notes: When unloading diesel fuel into a storage tank, ensure that water is not introduced into the storage tank and that the wrong product (such as gasoline), residual product in the tanker manifold or delivery hose is not accidentally introduced into the diesel tank.

It may seem like common sense but pay extra attention during the delivery fire process to verify that the storage tank to receive the diesel fuel is in fact the diesel storage tank. This starts with the appropriate API color code and product tag or label. If this is unclear, verify the appropriate tank with site personnel.

Next, position the tanker to ensure proper drainage. Make sure it is on a level surface to promote complete drainage from the compartment. If the delivery is a split load, unload the diesel fuel first. As the Fuels Institute report notes, diesel fuel storage tanks typically do not have a vapor recovery connection, so unloading diesel first will keep recovered gasoline or other products vapors from being pushed into a compartment containing diesel fuel.

Check for water and/or other debris around the fill pipe and take actions to ensure that these contaminants do not enter the tank. Verify the capacity of the storage tank and the product level inside the tank, and check the tank for water with an appropriate sensor system or stick with water-finding paste. If problems or discrepancies are identified, consult site personnel on how to proceed. And, of course, do not overfill the storage tank.

Verify that the compartment is empty after delivery and confirm the volume of diesel fuel delivered to the storage tank. If the volumes do not match, +/-1%, residual product may remain in the compartment.


Other Issues to Consider

It is important to be aware of the same considerations when delivering product to a marketer/wholesaler’s bulk plant. These can involve both underground storage tanks (UST) and aboveground storage tanks (AST). As is the case with the retail delivery, it’s important to check product delivery levels and check for the presence of water.

If contamination occurs, it’s important for it to be the “other parties’ fault.” Therefore, it’s imperative that the fuel delivery process be as button-down as possible to minimize the possibility of the wholesaler or common carrier being the source of potential contamination. In many cases, these best practices are in fact common practices; however, care should be taken to ensure that drivers are consistent and reliable with each load delivered.

This article provides an overview of the best practices to consider with the delivery process. The 14-page “Diesel Fuel Loading and Delivery: Industry Practices to Minimize Degradation and Improve Fuel Quality” report provides significant additional detail on how to implement the best practices and is available free from the Fuels Institute at