Diesel fuel is transported from the refinery to the storage depots by tanker trucks, ships or pipelines. From there it is loaded into another tanker truck and delivered to your site. Every time diesel is transferred from one tank to another, it not only transfers the fuel but also the contaminants present.

Many people assume they are buying quality fuel that meets the required specifications in terms of ISO 4406 and diesel fuel cleanliness is rarely questioned. However higher fuel systems operating pressures, lower system tolerances and tighter filtration have pushed fuel cleanliness into the maintenance spotlight.

Water gets into fuels and oils by adsorption, condensation and human negligence. Dirt and water act as catalysts for the breakdown of fuel via oxidation and by supporting bacterial growth – diesel bug. Although water in fuel is often hidden from the naked eye and its inert properties supposedly render it “harmless”, it can be extremely detrimental to most systems.

There are many different types of contaminants that could adversely affect, damage or even destroy a fuel injection  system. Bacteria, fungus, water, suspended microscopic particles, additives, wax are some of the main contaminants.

– Most of these operators have emergency generator fuel to allow at least 24 hours of operation.

– These generators are fed by one, or in most cases, multiple tanks of stored diesel.

– The quality of the stored diesel is both integral and critical to the reliable function of these generators.

– Microbial growth in diesel has accelerated year on year due to the reduction to almost zero of sulphur in diesel.

– The sludge layer caused by microbial growth is potent enough to cause fuel blockage, injector blockage and subsequently full engine failure.

– Regular cleaning of fuel to remove microbial growth is currently restricted to onerous, environmentally unfriendly and hazardous methods involving trucks, disposal, toxic chemicals, large numbers of staff, wastage and high costs.

– The CDA iCleanED replaces all the aforementioned negative treatment methods at significantly less cost with initial payback achieved after year one, and year two and onwards savings of 30% to 50%.

– With the above-mentioned iCleanED in place, any facility with stored diesel would be guaranteed a continual supply of clean, microbe free, water free, chemical free and particulate free diesel.

– Physical contamination: suspended microscopic particles, rust, dust particles, fibre material.

– Chemical contamination: water (moisture), gases, molecules of unwanted chemicals (such non-compliant fuel additives)

– Biological/microbial contamination: fungus, bacteria, viruses commonly known as DIESEL BUG.

– Dissolved water – Also known as RH% (relative humidity) or moisture is the water in dissolved state inside the diesel fuel. It is indistinguishable with the naked eye the presence can only be confirmed with specialised sensors or by laboratory analysis.

– Free water – accumulates at the bottom of the tank and it is present on the walls above the fuel line as a consequence of condensation. Because water is heavier than diesel fuel there is a distinct line separation between the two so the presence of free water is clearly visible. Free water can also be detected with specialised water in fuel sensors.

– Emulsified water – When the free water is mixed mechanically with the diesel fuel forming a cloudy/milky in appearance mixture.

One way or another, the water will find its way in any diesel tank either by refuelling with water contaminated fuel, condensation, leakage, ingress from atmosphere (humidity) and sometimes human error.

diesel bug

Diesel Bug was always a problem for diesel fuels, however, since the introduction of Ultra Low Sulphur Diesel (ULSD) it has become more and more evident, as sulphur was able to inhibit microbial growth in diesel fuels. The problem gets worse when biodiesel is added to ULSD and according to Australian Standard of fuel quality it can be up to 5%. The reason is that, compared to regular diesel, biodiesel is much more hygroscopic (attracts water). Studies found that biodiesel can absorb up to 25 more water than diesel and as the temperature increases above 35°biodiesel has an increased rate of 22.2ppm/°C – 9 times more than regular diesel. That is the reason why tanks situated in the engine room or in higher temperature areas have worse microbial contamination (up to few centimetres thick on the bottom of the tank). When that happens the primary fuel filters become constantly clogged.

diesel bug blocking filters

• In US in 1990 the Clear Air Act was amended to require stricter emission reductions of:

• So what does this mean? Among other things, it meant reduction of sulphur content from 500-3000ppm to less than 10ppm and the birth of ULSD (Ultra Low Sulphur Diesel). Without sulphur in it, for the first time in history, diesel now had the ability to grow microbial bacteria, essentially contaminating itself from within.
• Without protection a new type of contamination was created: THE DIESEL BUG
• Europe did the same few years later, in 2009, Australia followed suit.

As stated above, ISO 4406 is the reporting standard for fluid cleanliness. According to this standard, a code number is assigned to particle count values derived at three different micron levels: greater than 4 microns, greater than 6 microns and greater than 14 microns. The ISO code is assigned based upon Table 1 below:

Table 1 – ISO 4406 Fluid Cleanliness Guide

4µm / 6µm / 14µm and per / ml

For example: An ISO cleanliness code of 18/16/13 refers to the following:
18 = 4µm particles, 16 = 6µm particles, and 13 = 14µm particles.

By referring this information to the chart above, you can see the range of the actual particles within the index.
18 shows between 1,300 to 2,500 – 4µm particles, per ml of fluid sample
16 shows between 320 to 640 – 6µm particles, per ml of fluid sample
13 show between 40 to 80 – 14µm particles, per mil of fluid sample

It is recommended by most new diesel injector manufacturers to have an ISO Cleanliness Code in the range of 15/12/10 to 12/9/6.

– Fuel polishing – applies only to fuel – removes what conventional fuel filtering is not usually capable of (emulsified water that is suspended in fuel and doesn’t drop to the bottom of the tank to be drained).

– Clean Diesel D.E.B.U.G. system – applies to both fuel and the storage tank – on top of the 2 aforementioned filtration modes,  offers additional 2 levels of microbial decontamination with a proprietary wave lengh modulation UV and the optional O3 injection for the inside of the tank ensuring 100% kill of diesel bug.

When it comes to nominal contamination level in a diesel tank it means the average level of contamination of fuel sample taken from top and bottom of the tank.

Because of the restricted access to where the samples are taken from (usually from a single spot such as filling port or fuel sender port), this level of contamination is more an indication of what type of contamination is in the tank rather than the actual level.

When it comes to absolute contamination level in a diesel tank it means the percentage of evenly distributed contaminants throughout the entire fuel.

The novelty of our technology is that iCleanED machines perform like “shaking” the tank to put everything in suspension and then measure and remove the contamination until it reaches the desired ISO 4406 level.

1. Eliminates the need of expensive fuel replacement.
2. Eliminates the need of periodic tank cleaning.
3. Zero downtime during the cleaning process.
4. Dramatically reduces labour input.
5. Safer operation and reduced risk of injuries.
6. Reduced risk of environmental contamination.
7. Ensures true absolute ISO levels of cleanliness with F.A.C.T. technology.
8. Eliminates microbial contamination without the use of chemicals by UV exposure
9. Reduces risk of external contamination on refuelling with the dispensing function and inline treatment.

Part of the electromagnetic spectrum, ultraviolet radiation is split into three types.These are:

• UVA
• UVB
• UVC

The wavelengths of visible light are tiny, measured in billionths of a meter. A billionth of a meter is called a nanometer, or nm. UVA has a wavelength range of 320-400 nm, while UVB has a range of 280-320. Meanwhile, UVC’s range stands at around 100-280. If we take skin as an example, UVA may result in a tanning of the complexion, while UVB may mean it burns. The common effect of UVC IS germicidal, which is the scientific term for killing or inactivating microorganisms by destroying nucleic acids and disrupting their DNA. This renders them useless when it comes to performing critical cellular functions.

1. The F.A.C.T. cleaning algorithm.
2. The proprietary electromagnetic signature of the UVD light within the D.E.B.U.G. system.
3. The proprietary design of flow and return tubes and heads.

The algorithm is what took years to develop and allows the machine to self-sample, process, treat and repeat as required. The right wavelength modulation also took years to develop and keeps the fuel stable whilst using UV to kill microbial growth and all other living bacteria / fungus. The flow and return tubes and heads agitate all the fuel in the tank and ensure all particulates, water and microbes are passed through the machine and sanitised/filtered/separated.

The F.A.C.T. cleaning algorithm is a model based control application where multiple independently measured inputs are evaluated by a controller which then commands multiple outputs such as pump speed, fuel priming, flow direction, flow rate controller and the proprietary UVD fuel decontamination system.  The monitored inputs are fuel flow, fuel temperature, differential pressure in the multistage filtration system, relative humidity of fuel, water concentration and fuel contamination in accordance with the ISO 4406 international standard code for fuel cleanliness. The calculation is performed in real time to decide the flow control rate and direction and the intensity of the UVD fuel decontamination system in order to decontaminate and clean the fuel in the fastest time and the minimum amount of consumables while providing 100% guaranty compliance with the ISO 4406 and AS3570 for fuel cleanliness. This calculation is built on a mathematical model (the F.A.C.T. algorithm) considering the changes such as flow/viscosity with temperature, filter blocking tendency based on the differential pressure changes in real time with trends, water content and so on, rather than a simple feedback loop used in conventional filtration (e.g. filter blocked – pump stop – change filter). The advantage of this new innovative filtration technology gives iCleanED machines the ability to react proactively to changing input conditions rather than changing output conditions like a traditional filtration system.

More information here

ISO 4406 is the reporting standard for fluid cleanliness. According to this standard, a code number is assigned to particle count values derived at three different micron levels: greater than 4 microns, greater than 6 microns and greater than 14 microns. The ISO code is assigned based upon Table 1 below:

Table 1 – ISO 4406 Fluid Cleanliness Guide

4µm / 6µm / 14µm and per / ml

For example: An ISO cleanliness code of 18/16/13 refers to the following:
18 = 4µm particles, 16 = 6µm particles, and 13 = 14µm particles.

By referring this information to the chart above, you can see the range of the actual particles within the index.
18 shows between 1,300 to 2,500 – 4µm particles, per ml of fluid sample
16 shows between 320 to 640 – 6µm particles, per ml of fluid sample
13 show between 40 to 80 – 14µm particles, per mil of fluid sample

It is recommended by most new diesel injector manufacturers to have an ISO Cleanliness Code in the range of 15/12/10 to 12/9/6.

A NOTE ON THE FIGURES USED

Note that some of the table entries are defined as cumulative counts (e.g. “> 6µm”) and others are defined as differential counts (e.g. 6–14µm”). Instances of particle sizes given as “µm” refer to ACFTD (i.e. Air Cleaner Fine Test Dust) distributions. Instances of particle sizes given as “µm(c)” refer to MTD (i.e. ISO Medium Test Dust) distributions.
All standards are in counts per volume, and provide easy methods for converting particle counts into limits that are simple to interpret. By noting the requirements of the standard, particle counts can be accurately converted to contamination levels.