Meeting ISO 4406 Cleanliness Standards with Diesel and Biodiesel Fuel

Meeting ISO 4406 Cleanliness Standards with Diesel and BioDiesel FuelDiesel and Biodiesel fuels may leave a refinery clean, but fuel quality can vary at the time it is dispensed due to contamination accumulated during transport and storage. Operators and engine manufacturers report that the majority of engine issues are due to dirt and/or water in the fuel. This is especially challenging at remote sites such as mining sites, terminals, power generation, and retailers.

As diesel engines adopt more efficient High-Pressure Common Rail (HPCR) systems, demands for removal of abrasive particles smaller than 6 microns are rapidly becoming a standard. Clean diesel fuel plays a vital role in reducing maintenance and overall operating cost. 


Guide to contamination standards

Solid contaminants in fluid systems vary in size, shape, form and quantity. The most damaging contaminants in hydraulic systems are normally between 6 and 14 microns, and therefore cannot be seen by the naked eye. 

Parker has provided a contamination guidebook which is aimed at engineers, technicians and quality control personnel involved in contamination control. Its purpose is to make available accepted and widely-used cleanliness specification levels for liquid samples. The tables in this guide allow users of using automatic portable particle counters to see the relationship between raw particle counts at various sizes and the reporting code numbers of various contamination standards. 

ISO standard 4406:1999 provides a way of summarizing the distribution of contaminants in a fluid by counting the particles per 100ml sample of hydraulic fluid: the figures are cumulative. To make the numbers less cumbersome, they are converted to number codes, as in the following table. Each code measures a “channel” of representative particle sizes that are particularly associated with wear and damage in hydraulic systems: these are 4µm(c), 6µm(c) and 14µm(c). For example, 700 000 particles larger than 4µm(c) corresponds to ISO 20 (as 700 000 is more than 500 000 but fewer than 1 000 000). In the same way, 140 000 particles larger than 6µm(c) corresponds to ISO 18; and 7 000 particles larger than 14µm(c) corresponds to ISO 13. So this fluid would be reported as 20 / 18 / 13. When the raw data in one of the size ranges results in a particle count of fewer than 20 particles, the scale number for that size range is labeled with the symbol ‘>’.

Meeting ISO 4406 Cleanliness Standards with Diesel and BioDiesel Fuel


Suggested acceptable contamination codes for various types of systems:

Meeting ISO 4406 Cleanliness Standards with Diesel and Biodiesel Fuel  - suggested levels of contamination chart - Parker Hydraulic and Fuel Filtration Division



Meeting ISO 4406 Cleanliness Standards with Diesel and Biodiesel Fuel - DFF Filtration System image -Parker HannifinMining - Today’s electronically controlled diesel engines utilize the latest high-pressure common rail systems that require pressures up to 30,000 psi with injection tolerances down to 2 microns. Given the mining environment, meeting downstream ISO 4406 Cleanliness Standards for bulk fuel storage, dispensing, and during transfer can be challenging. Parker Velcon offers the filtration and process fuel monitoring technology that extend equipment up-time and assures clean dry fuel. 

Refinery/Terminals - In the process of refining, storing in terminals and distributing bulk diesel fuel, contaminants such as abrasive silica, pipe scale and water are commonly introduced. As fuel is transported, it can quickly deteriorate fuel quality below ISO 4406 Cleanliness Standards required for use in today’s diesel engines. Our filtration and separation solutions are designed to remove contaminants so that the fuel supplied to customers at distribution meet or exceed original manufacturer specifications.

Power Generation -  Diesel powered plants require large fuel storage reservoirs and tank farms that must be available on demand. Velcon’s fuel monitoring products can help ensure that fuel is monitored for contaminants. Our filtration and separation products are used to remove particulate and water and to ensure that fuel quality meets engine ISO Cleanliness Standards in order to assure reliability.

Transportation - Fuel is the number one operating cost for transportation fleets. The trucking and transportation industry depend upon the reliability of the diesel engines and the diesel fuel. Poor fuel quality directly affects maintenance cost, fuel expenditure, fuel efficiency and overall operating costs. From monitoring the quality of the fuel source to ensuring that engines utilize fuels that meet ISO 4406 Cleanliness Standards, Velcon provides solutions to help manage and meet your diesel fuel needs.

Retail - Retailers rely on their fuel suppliers to provide quality fuels that meet regulatory requirements and consumer demands. Nevertheless, fuel stored and transported can acquire particulate and water contaminants that lower the quality below required specifications. Velcon’s filtration and separation solutions are designed to remove these contaminants and return fuel quality to desired levels.


Meeting ISO 4406 Cleanliness Standards with Diesel and BioDiesel FuelFor over 60 years, Parker Hydraulic & Fuel Filtration Division (HFFD)  has supplied filters for fuel conditioning for applications from 5 gpm to more than 5,000 gpm. Our proven bulk fuel handling experience in combination with the world’s largest indoor fuel lab have allowed us to develop a range of high-quality products to meet the most stringent diesel and biodiesel fuel market needs.

Providing high-quality fuel to the modern high-pressure common rail fuel injection systems is imperative to avoid costly downtime and engine repair.







Meeting ISO 4406 Cleanliness Standards with Diesel and Biodiesel Fuel - David Tice Parker Hannifin Article contributed by David E Tice, market development manager, CleanDiesel, Energy and Marine, Parker Engine Mobile Hydraulic and Fuel Filtration Division.





Additional articles related to filtration:

What You Need to Know About Testing Your Hydraulic System for Particle Contamination

Reduce Failure of Hydraulic Systems with Preventive Maintenance

Clean Hydraulic Fluids Are the Key to Top Performance

Water - A Diesel Engine's Worst Enemy

Water - A Diesel Engine's Worst Enemy

Dealing with Condensation and Filtration Problems: A Guide for Diesel Boat Owners

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