When you’re lining up plans for antigel treatment of diesel fuel, there are two key variables you need to have a handle on. When can you expect to have to deal with the problem? And what’s it going to take to get your fuel where it needs to be with respect to gelling prevention?
To put it another way, cold weather treatment of diesel fuel relies on having the anti-gel treatment in the fuel before it starts the gelling process. Antigel chemistries work by acting on the wax AFTER it comes out of the fuel. This is one reason why most antigels won't have an appreciable effect either way on cloud point - they more affect cold filter plug point and pour point temperatures.
Knowing this means that in order to effectively prevent fuel gelling problems, it requires you to have some kind of idea of the temperature at which this might happen in your fuel. In other words, you need to know what temperature your diesel fuel gels, and you need to know how much antigel you’ll need to use in order to get the level of protection your diesel fuel needs.
Professional fuel users have a good idea when they need to add a cold flow improver because they generally know the cloud point temperature of their fuel. They keep track of outside temperatures so that they have an idea ahead of time when they need to break out the antigel (since it needs to be in the fuel before the fuel gets too cold).
Listen to our Fuel Pulse Episode 035 – When To Treat For Cold Flow
As a user, you should start considering cold-weather treatment when the temperature drops within 10 degrees of your fuel's cloud point. Sometimes you can get that information from your fuel supplier, but if they don't have it, it's safe to assume a cloud point of around 18 degrees F (since that's the most common spec for diesel fuel from the Colonial Pipeline). You want to treat at temperatures above the cloud point because the cloud point refers to the temperature at which enough wax has been released in the fuel that it becomes visible (i.e., it appears cloudy). In reality, wax starts coming out at temperatures above the cloud point. And this means you want to have that antigel present in the fuel when it first starts happening, so it can start working on the wax from the beginning.
Recently, we did a video blog where we talked about this kind of issues that professionals are facing with respect to cold flow and prevention of diesel fuel gelling problems. If you missed it, feel free to have a look: