Protect Tier 4 engines with proper DEF handling

Diesel exhaust fluid (DEF) is contaminated by direct or airborne contact with many common elements. As little as a tenth of a teaspoon of many contaminants is enough to bring a 5,000 gallon tank of DEF off-spec.

Steve Ile, territory sales manager at Thunder Creek Equipment, offers insights on how to prevent and protect DEF from contamination.

Tips for DEF use in off-road equipment

  • Protect DEF from exposure to direct sunlight.
  • Protect DEF from extreme temperatures.
  • Protect handling systems from expansion when DEF freezes.
  • Never use additives to prevent freezing. 
  • Purchase API-certified DEF from a reputable source.
  • Only use closed or sealed systems. A sealed system is a single-use container, like a jug or a drum; a closed system is reusable and can be filled through a closed coupler.
  • Never reuse or refill single-use containers that have been opened.
  • Never use dispensing equipment like funnels, transfer containers, pumps, seals, fittings, or hoses that are not made in accordance with the ISO 22241 Standard.
  • Remove dirt and debris around the DEF fill port on machinery.

Off-road equipment different from on-highway equipment
For on-highway industries, the machine goes to the DEF refill location, but in off-highway applications, DEF must be delivered to the machine.  This distinction is significant because DEF is easily contaminated and off-road environments are, quite frankly, dirty.

It’s not often that a truck stop is considered clean, but when compared to a construction site, a farm field or a quarry, it is. It’s also easier to control the environment around a fixed source of DEF than a mobile one. There are ways to prevent DEF contamination in the field.

What contaminates DEF
Common sources of DEF contamination are dirt, dust, fuel, oil, and debris; earth metals found in tap water; and copper-, chromium-, zinc- or nickel-plated metal found in fittings, couplers and other fluid handling equipment.

The greatest risk of contamination occurs when DEF is transfered to the machine. If DEF is handled the same way fuel and other fluids are handled, it's likely DEF will be contaminated. 

The ISO 22241 Standard identifies proper practices for making and handling DEF. When considering DEF transer and storage equipment, make sure the manufacturer uses materials approved in the standard. At Thunder Creek, for example, DEF hoses are manufactured in an isolated area to ensure there is no cross-contamination from other areas of the facility and each system is sterilized and sealed in accordance with the standard.

Effects of contaminated DEF
Contaminants affect the catalyst in the selective catalytic reduction (SCR) system. The inside of a catalyst is structured like a honeycomb and over time, contaminants get trapped in that honeycomb structure. Some will cause corrosion as they react with DEF, which is 32.5 percent urea. Others form gummy deposits that will eventually plug the catalyst.

Damage to the catalyst is not immediate, but once contaminants have been introduced, damage is irreversible and can’t be repaired – only replaced. SCR systems use rare-metals catalysts. These are expensive and are usually not covered by warranty.

Contaminants can also affect the injection system of an SCR system, plugging it as the fluid is injected into the exhaust system. A system using contaminated DEF becomes less effective at removing emissions, so it will begin to consume more DEF. Eventually, the damage will cause the SCR system to shut down. Depending on the machine, this may either initiate a fault code or shut the machine down entirely. Once signs of contamination are present, it’s usually too late.

How to prevent contamination
DEF purity is irrelevant without proper handling practices. Best practice is to handle DEF like a hospital handles surgical equipment. If the scalpel is manufactured in a sterile environment but the janitor punctured the package when it's put it in the supply closet, it’s no longer clean.

The Thunder Creek DEF solution prevents contamination with an exclusive 2-in-1 DEF pumping system. This is a closed system that fills and dispenses DEF without exposing it to contamination. It’s the key that makes our solutions ISO compliant for life.

Temperature affects DEF quality
Prolonged exposure to direct sunlight and higher temperatures will cause DEF to degrade faster. Generally, this is how temperature affected DEF quality and life:

Temperature    DEF life 
Up to 50F           3 years
Up to 77F           1.5 years
Up to 86F           1 year
Up to 95F           6 months

DEF freezes at 12F; freezing and thawing do not affect the chemical properties of DEF, but the fluid needs to be fully thawed before use. Also, DEF expands by approximately seven percent when frozen. This can cause damage to pumping components and fully-filled, closed containers.

Temperature and humidity may also impact DEF consumption. When the engine intake air is warmer and more humid, more NOx is created through the combustion process, therefore more DEF is required to remove it.

DEF filtration systems do not remove contaminants; they only remove particulates that may be present in the DEF. 

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