The Dirt on Diesel Fuel Filter Ratings

diesel filter manufacturersFor many diesel drivers, fuel filtration can prove to be confusing. They know it’s an important part of their engine’s overall good health, but don’t often get into the details. Today’s diesel fuel systems are highly efficient, providing an estimated 45 MPG on the highway and they demand quality filtration to help them run at peak efficiency. To keep up with the ever-changing filter industry, it’s important to know all there is to know about the filtration standards as diesel engine technology continues to advance. You’ve likely invested a lot of money into your diesel vehicle and you want to make sure that investment stays protected. One way you can do this is by learning how diesel filter manufacturers rate their filters and how effective they are. What do the various ratings mean and how critical are they for keeping your diesel engine running smoothly?

What is a filter rating?
The main job of diesel fuel filters is to work with the diesel fuel pump to keep out impurities like water, rust and dirt, to prevent them from passing on through the filter. Fuel filter manufacturers rate their products depending on their ability to prevent particles of a certain size to pass through. This rating is given by diesel filter manufacturers in a number of microns, and the number depends on how large or small the particles are which the filter can effectively remove. But the number alone doesn’t determine the ultimate effectiveness of a filter. Other factors include Absoulte, Nominal and Beta Ratings.

Absolute isn’t always absolute
Absolute Rating, a term given by diesel filter manufacturers, might sound like it means that a particle no bigger than a given size will pass through the holes in a filter. It should mean that if a particle is larger than the hole, it won’t pass through. But there is some discrepancy between filters that are tested in a lab using glass beads and a real world situation where temperatures in an engine are going to be higher with more vibration. Also, variances in manufacturing can create differences within the filter where the pores may not all be consistent in size. This creates the possibility that if you have a filter that is 10 microns in size for example, that a larger particle might sneak through. But the definition of Absolute Rating ensures that the number stated is the upper limit of the filter.

Nominal isn’t always nominal
Along with a filter’s Absolute Rating, its Nominal Rating reflects the ability to prevent a certain percentage of particles over a given size from getting through. The figure given for a Nominal Rating might be stated as “95% of 10 microns”, which translates into the filter trapping nearly all particles 10 microns and larger from getting through. But on the flip side, a small percentage of particles over 10 microns might not be caught.

Beta Rating: Combining Absolute and Nominal
Since the above ratings scales have some constraints, the diesel fuel systems industry developed the Beta Rating, which takes into account both the size of the particles which pass through the filter and how many make it. For example, a filter that is assigned a Beta Rating of “2 of 10 microns” means that in laboratory testing using a 10 micron filter, 2 particles were detected as being trapped by the filter, whereas 1 particle was detected as passing through. In other words, a filter with a Beta Rating of 2 successfully filters out 50% of the particles thrown at it. Obviously here you want to look for a filter with a high Beta Rating, as that means it will be more effective in keeping contaminants out.

When researching diesel fuel filters, be sure to keep all of the above information regarding ratings in mind instead of just relying on one number. This will help to maximize the efficiency of the filter. If you still have questions, contact your diesel filter manufacturers or suppliers for more information.