The historic cold snap that gripped New England and the Mid-Atlantic to kick off the new year challenged fuel handlers, causing sporadic operational issues for diesel fuel distributors and their fleet customers.
One phenomenon that caused problems was the formation of a white grease-like substance that suffocates fuel filters and doesn’t melt at room temperature — as one might expect — and is not related to biodiesel.
With regional cloud points ranging from 9 to 15 degrees Fahrenheit, this substance would form after a delivery truck offloaded fuel from its cold aluminum tank into above ground storage tanks subjected to ambient temperatures as low as 2 degrees. The fuel would then be pumped into diesel vehicles, where it was left to sit idle and unprotected from the elements, sometimes for days.
Even if this fuel were properly winterized and rated to operate down to a minus 20 CFPP (cold filter plugging point), without garaging the trucks, heat taping the filters and saddle tank, draining water from the saddle tanks or maintaining the water-fuel separators, it still would likely be compromised while sitting in a fuel filter’s housing for a long duration under such extreme conditions. So, when it came time to operate the trucks, it’s not surprising that some fleets were finding this white grease-like substance suffocating their filters.
When something like this occurs, it’s generally advisable to remove fuel filters from the housings and take them into the garage. If after 20 minutes there is a pool of water under the filter, moisture is contaminating the fuel. If the material begins to melt, slowly sliding off the filter media, and looks creamy, it probably is paraffin. If the material does not come off the filter, however, two other scenarios are possible.
In the first, when biodiesel is present and moisture extracts monoglycerides out from the fuel, a wax buildup appears on the filters. The second, less commonly recognized scenario, happens in No. 2 ultra-low-sulfur diesel, which is a mixture of n-paraffin hydrocarbons. These paraffin are only liquid in diesel fuel at room temperature. As the fuel is exposed to lower temperatures, longer chain hydrocarbons start to come out of solution and get caught on the filter, eventually blinding it. The lighter ends remain a liquid and pass through the filter or get trapped in the filter canister.
These liquids typically are what is found in the container when it arrives at our testing facilities. Without a strong solvent such as xylene, the heavier end paraffin that blinds the filter will not go back into solution.
In the absence of higher temperatures, diesel fuel itself doesn’t have enough solvency power to dissolve the wax on the filter. Heavy, waxy fuels have more of these higher chain hydrocarbons, which is why our region has been seeing more of this “white grease” that doesn’t melt at room temperatures. Under these circumstances, it is not biodiesel-related, just long chain ULSD hydrocarbons—something that your regional suppliers can’t control.
With this in mind, who is responsible for ensuring that diesel fuel performs optimally in the customer’s tank? The truth is, everyone in the supply chain is responsible — including the end users. Whoever is treating the fuel with additives and kerosene is responsible for proper and accurate blending. The company lifting the fuel from the terminal is responsible for making sure that the delivery truck being used is kept clean and dry. (They should be sticking the customer’s tank before and after deliveries as well.)
The customer needs to understand the operability points of the fuel as well as the seasonal temperatures that the fuel will subjected to. If the fuel is rated for a specific CFPP, but when it leaves the terminal is introduced into another diesel fuel (even if it is from the same terminal), the fuels then become different from what was lifted from the rack.
Know what is in the tank, understand what you are buying and plan accordingly with preventative fuel-quality maintenance strategies. Clean, dry fuel that is formulated to perform in cold weather is a responsibility to be shared by all.
Established in 1996, Advanced Fuel Solutions Inc. provides fuel-quality solutions, seasonal and year-round fuel additives, and fuel-quality management services for fuel dealers and fleets nationwide.