Dirty Diesel

Removing Dirt Protects Engines​ 

When people think about fuel contaminants, the first thing that comes to mind is dirt. It seems obvious that abrasive wear cannot be good for a fuel system, and it’s not. So, why don’t people pay more attention to keeping dirt out of their fuel? Diesel is generally clean when it leaves the refinery, but contamination enters each time it is transferred or stored, all the way through to the moment when it is burned. Is hard particulate damaging your equipment or rapidly clogging your filters? If so, the first thing to do is to isolate the problem by testing the cleanliness of your fuel at each critical point: at delivery, inside your bulk tank, and at the dispenser. This will help you prioritize the action steps that will improve your fuel quality the most: cleaning fuel before it is delivered, improving tank conditions, installing filtration your dispensers, or other. 

If your diesel is delivered dirtier than it should be, then there is a conversation to be had with your supplier. Most likely, however, your fuel deliveries are perfectly compliant with diesel industry specifications, so the distributor is probably not doing anything “wrong”. That said, handling practices are very important. Diesel quality can vary greatly supplier to supplier depending on how well their operation is run. A good supplier adds a lot of value. Purchasing decisions based solely on price are seriously discouraged. The cost of a bad load is far greater than the few pennies per gallon or liter that might be saved by bargain shopping. If you play the "diesel lottery", sooner or later, you will lose. High volume diesel users may be able to set their own requirements and convince the distributor to install filtration at his terminal or on the delivery truck, but for most this is not a viable option. It is up to you to ensure that your fuel is cleaned to the level required by your equipment. The average cleanliness of delivered fuel varies greatly depending on region. 
dirt paper ”folded

The images to the left were taken in the Middle East, where hard particulate contamination is a huge issue for new and old equipment alike. In areas like this, it is best practice to test every load of fuel before accepting delivery. Even with testing, equipment failure is a common occurrence if fuel is not aggressively filtered on site. 

In Australia, Europe and North America fuel is typically delivered much less dirty, but still not clean enough for use in most equipment. Testing is the only way to accurately assess the cleanliness of your diesel. Any reputable oil analysis test lab can do this for you, or you can easily monitor it yourself with a manual particle count patch test kit and USB microscope. 

Install a high efficiency single pass filtration system at the inlet to your bulk tank to clean fuel down to recommended cleanliness levels. This not only protects your equipment, it also protects your existing diesel investment and your tank from the risk of receiving a bad load of fuel. A good tank cleaning is expensive and time consuming. 

Work sites tend to be dirty places, and fuel continues to be contaminated each time it is transferred or stored. The task at hand is to prevent additional dirt from getting into the diesel after it is in your bulk tank. This is something every fuel user can and should take steps to control. Dirt can get into your bulk or onboard fuel tank upon delivery, from the air, from the tank, or from direct contact. This can be prevented or minimized by good handling practices. 

Good handling checklist: 

      • ​​​​Inspect all tanks to ensure that they are ​properly sealed, with no cracks, loose fittings or other 
        openings where dirt could get through. 
      • ​​Inspect all breathers. Many breather pipes have little to no protection from airborne dirt and contaminants. Install high efficiency breather filters to protect from dirt. Combination air filter and desiccant (deliquescent) breather styles are best, since they protect from both ambient dirt and humidity. 
      • ​​Inspect all transfer and dispensing points and take measures to ensure that dirt is not introduced into the system through negligence. 
      • ​​Inspect the inside of the bulk storage tank on a regular basis. Test samples from the bottom, middle and top to determine the presence of dirt, water or other contaminants. 
      • ​​​Drain and clean tank periodically if it is contaminating your new fuel deliveries. ​ 

Kidney loop filtration with a portable filter cart is another option for cleaning up tank contents. It is especially suitable for smaller diesel volumes. Make sure that the tank level is low before kidney looping. This isolates the contaminants concentrated at the tank bottom and does not mix them up with large volumes of cleaner fuel on top. ​

Because unstable fluids and the tank itself can be sources of contamination, final filtration at the dispenser is recommended. This is the most critical place to filter. It ensures that only clean, dry fuel reaches your valuable equipment. Depending on flow rate and total diesel usage, dispensing filtration can be as simple as a single filter mounted on your fuel pump. Installations can be scaled to handle any fuel flow, from a single low flow pump to a high volume commercial terminal. 

Not all diesel filters are created equal. Some remove only "rocks and sticks", while others remove over 99.9% of all contaminant down to the size of a single cell of bacteria. It is important to use a filter that will clean diesel to recommended levels. To accomplish this, the bulk filter should be just as efficient as the onboard secondary fuel filter specified by the manufacturer of your equipment. Numbers of particles and total contamination amounts increase dramatically at smaller particle sizes under 4 microns. If you are not filtering out particles of this size at a high efficiency rate, then you are doing little to protect your equipment or extend the life of your onboard filters. No matter which filter you select, testing your fuel is the only way to know for sure that it is clean enough. 

With the introduction of high pressure common rail fuel systems, the demands on onboard filtration increased exponentially. Helping out the onboard filters is one reason that bulk filtration prior to fueling is recommended. It will extend onboard filter life significantly while adding an extra layer of insurance to ensure your entire fuel system meets expected parts life and scheduled service intervals. 

Filters are now expected to remove much more contamination in terms of particle size, efficiency (percentage) and total volume. High tech synthetic medias do a very good job of both cleaning better and holding more than ever before. But just because a filter will "fit" on a particular application does not mean that it is up to the original manufacturer specification. Cross referencing does not necessarily mean equal performance. 

Follow equipment manufacturer specifications and be sure to check the Beta 
Ratio (efficiency) of a filter, not just the micron size. A "10 micron" filter that only removes half (Beta 5(c) = 2) of all particles 10 microns and larger is not at all the equal of a "10 micron" filter that removes 99.9% of all contaminant 10 microns and larger (Beta 10(c) = 1000). Donaldson fuel filters are proven to meet or exceed equipment manufacturer specifications.