Diesel Fuel Filtration: New Technology and Old Habits

by Steven Katz

This is not another story about the importance of changing your fuel filters – you already know all there is to know about that. This story is about the best practices for where, what and when to use the proper diesel fuel filters for the main engines and generators. While the general principals of fuel filtration have not changed, advances in technology mean that some older habits may need to be updated for today’s newer engines.

Before getting into filters, let’s talk about newer high pressure common rail (HPCR) technology for marine engines. Some HPCR engines have final fuel pressures as high as 30,000 psi. “The higher pressure of the common rail fuel injection allows the engine to atomize the fuel and air mixture better so more of the fuel burns in the cylinder, reducing particulate emissions,” said Jeff Sherman, marine sales manager for MTU.

These engines need to have very clean fuel. Most engine manufacturers require the fuel supply to meet ISO 4406 standards for a particle count rating of 18/16/13. This coding system (i.e. 18, 16, 13) corresponds to the numbers of particles of a size greater than 4, 6 and 14 microns per milliliter of fuel respectively.

The number 18 expresses that there will be a maximum of 2,500 particles equal to or larger than 4 microns. The number 16 indicates that there will be a maximum of 640 particles equal to or larger than 6 microns. The number 13 represents that there will be a maximum of 80 particles equal to or larger than 14 microns in a milliliter of fuel. The critical maximum particle sizes for modern injection systems are between 4-6 microns. These particles are smaller than what can be detected by the naked eye.

Today’s low emission and high power engines have drastically increased the reliance on the technology and electronics. Modern high performance diesels rely extensively on electronics. The requirements for extra clean fuel are part of this equation, along with clean electrical power and precise maintenance requirements for components such as oil and coolants.

The cleanliness of fuel is not to keep the system from clogging (that’s a given these days). Clean fuel can also prevent abrasive damage and subsequent accelerated wear. Damage and wear from dirty fuel can quickly occur. This can cause a number of issues: from effecting the injectors and other system components, to resulting in degraded performance, increased emissions or component failures.

The best way to ensure you have clean fuel is through multistage filtration. This generally involves a system where the fuel from the storage tanks flows through progressively finer filters before arriving to the finest (smallest micron) engine-mounted filter. Working on engine-mounted filters (secondary filters) can be an intimidating proposition.

There are some folks who don’t like changing the secondary filters, understandably so. Changing engine mounted filters is expensive, time consuming and can easily induct air into the fuel system during a change. This causes some operators to install a finer (smaller micron) filter in the primary filter location in the hopes they can prolong the life of the secondary filter. This is not acceptable in today’s engines and not recommended by engine manufacturers.

The popular Racor Turbine Series primary fuel filter is designed to remove water and particulates of larger size (30 or 10 micron at a given efficiency ratings) and the engine-mounted filter is………………………………………………… Click Here to continue reading this article.