Days are getting shorter and nights are rapidly getting cooler. To ensure fewer problems with diesel fuel during cold weather, it is recommended that cold flow improvers, like FS SURE-FLO, be added as fuel temperatures reach 10-15oF above the fuel's cloud point (CP). Based on recent testing, cloud points in Midwest fuels can be as high as 10-11oF. Since it isn't always possible to know where fuels are sourced, it can be difficult to predict a specific fuel's CP without laboratory testing. It is especially important to treat fuels if they are stored for several months prior to use.
Both gelling and icing can plug filters and cause operating issues during cold weather. Icing is the situation when water in the fuel turns into small ice crystals. Even with the best fuel quality management practices, small amounts of water can freeze and plug filters. High-performance cold flow additives, like FS SURE-FLO, contain de-icing chemistry to prevent operability issues caused by fuel icing.
Diesel fuel is also prone to waxing or gelling in cold temperatures. As diesel fuel cools, small crystals of wax come out of solution and stick together to form agglomerates. The heavier crystalline structures ultimately sink to the tank bottom where they are pumped into fuel lines.
The cloud point of the fuel is the temperature at which the paraffin/wax crystal agglomerates are large enough to become visible and give the fuel a cloudy appearance. However, the crystals start forming, well before they are visible in the fuel.
FS SURE-FLO is designed to bond with new wax crystals as they are formed and prevent them from combining into bulky agglomerates. By keeping the crystals smaller and dispersed, the fuel may still appear cloudy, but filters and fuel lines still operate normally because agglomeration into larger particles has been reduced.
Diesel cold flow chemistry is not designed to break-up agglomerates that already exist in the fuel, but only prevent them from forming. This is why we recommend treating the fuel at temperatures well above a fuel's cloud point. But when gelling has already occurred, emergency rescue treatments are available for use on a temporary basis to break up filter-plugging wax agglomerates that have already formed.
For best practices to ensure cold weather diesel operability, call your local FS Energy Specialist today.