Aggregate producers should minimize unscheduled downtime however they can. Sometimes, minimizing downtime means looking in unexpected places for trouble spots.
One potential trouble spot is diesel supply. Every gallon of diesel fuel is fraught with potential contamination, and diesel that isn’t pristinely clean can wreak havoc on expensive high-pressure common rail (HPCR) engines.
HPCR fuel systems used in today’s low-emission diesel engines deliver much better efficiency but, due to smaller tolerances at the injector, they are more susceptible to failure compared to older-model engines.
Before the rollout of HPCR engines, “clear and bright” was a standard for fuel cleanliness. You could do a visual inspection of your fuel and be confident it was safe for your engine. Today’s systems, however, are much more susceptible to damage from contaminants that cannot be seen with the naked eye.
Did you know the eye can only see particles that are at least 40 microns in size? And did you know particles that can damage HPCR injectors are only 2 microns in size? That’s the size of bacteria.
Fuel quality issues, including dirt, typically show up as reduced fuel economy, higher rate of diesel particulate filter (DPF) regenerations, prematurely plugged on-engine fuel filters, loss of horsepower, DPF failure and, ultimately, fuel system failure.
In most off-road industries, an engine or fuel injector failure is a worst-case scenario.
Replacing or repairing an engine is one of the most costly equipment-related issues possible. In mining, a loader or haul truck being offline for several days can result in unrecoverable costs. Even a few hours of lost production can add up.
Knowing the Problem Points
The question for the aggregate producer then becomes: How do you keep diesel clean for engines with newer, more advanced technology? The short answer is filtration. But to better understand this, producers need to have a grasp of all the places fuel can become contaminated along its journey.
“Because most HPCR engines feature tolerances of less than 2 microns, dirt particles that are as small as bacteria can cause pitting and, eventually, injector damage,” says Paul Klick, mobile hydraulics product manager at Donaldson. “People can transmit bacteria with a sneeze or a touch, so you can imagine how a simple fuel transfer in a dirty environment can introduce all sorts of trouble to a diesel supply.”
Fuel, in its final state, leaves the refinery by truck, rail, barge or pipeline. In most cases, there’s a transfer during this stage – and each part of the transportation cycle allows for contamination.
There are specifications in place for the handling and management of diesel fuel, but they were implemented in the 1950s and simply haven’t kept up with the technology requirements in today’s HPCR engines.
Then, there is a transfer when the fuel arrives at the bulk terminal. This is another opportunity for dirt, water and chemistry issues to invade the fuel supply.
Diesel is delivered by truck from the bulk terminal to end-user sites, where it is transferred to on-site storage. That’s one “out” and one “in” transfer – or two more opportunities for dirt ingression.
Once diesel is in “final” storage on site, the fuel can then be transferred to smaller day tanks, mobile fueling trucks or dispensed directly into equipment. The potential for contamination is highest here as every time fuel is moved, contamination ingress is possible.
“Local distributors have federal cleanliness standards that they must meet, and most do,” Klick says. “The problem is that our industry regulatory standards have not kept pace with the requirements of our engines. A fuel-jobber can be doing their due diligence the same way we have always done it, but now the fuel is too dirty for newer engines on the lot.”
Problems in Bulk
Equally problematic, if not more so, are the final fuel tanks themselves.
Bulk fuel tanks are contamination hot spots. Dust can enter through exhaust vents. Every time fuel is pumped in or out of a bulk tank, sediment or other gunk that’s been resting on the bottom can be churned up and can go right into your equipment.
Moisture is diesel’s worst enemy. If water gets into that bulk tank, it can cause rust on the inside of the tank. If enough moisture gets in, bacteria can begin to grow by feeding off the fuel.
Additionally, water makes biodiesel unstable and can cause glycerin fallout, which can clog bulk and onboard filtration. Free water in diesel can cause corrosion, etching or channeling of the injector sealing face, and even blow off injector tips.
Paul Klick, Donaldson Mobile Hydraulics Product Manager
Filtration as a Solution
Nothing is foolproof, but effective filtration goes a long way in protecting your engine, according to Klick.
“Today’s advanced filtration media is designed to protect engines beyond current industry standards,” he says. “We obviously recommend high-efficiency onboard filtration, but you can’t overlook proper filtration on every external tank you have, too.”
Proper filtration includes inlet filtration, breather filtration on the tank’s venting system, and every dispense pump should be outfitted with a good particulate filter and water-absorbing technology.
Whether onboard or off, remember that not all diesel filters are created equal. Some are capable of removing only (literally) rocks while others remove more than 99.9 percent of all contaminants that can harm modern HPCR engines. The bottom line: Use a filter that cleans diesel to the recommended levels the engine requires.
