It Doesn't Take Much to Contaminate Diesel Exhaust Fluid

Nov. 23, 2016

Maintaining the integrity of DEF is vital to protect Tier 4 engines, but it may not be as easy as you think. Common elements found around containers and tanks, on your equipment, and in your shop, can wreak havoc.

All they have to do is find a way in.

“DEF is highly sensitive to chemical impurities and is corrosive to certain metals such as steel, iron, zinc, nickel, copper, aluminum, and magnesium—and as little as 1/10th of a teaspoon of many common elements is enough to bring an entire 5,000-gallon tank of DEF off spec according to the ISO 22241 standard,” says Luke Van Wyk, general manager of Thunder Creek Equipment.

Contaminants include copper,
zinc, chromium, nickel, iron, aluminum, phosphorous, magnesium, calcium, sodium and potassium.

“Even something as simple as tap water can bring DEF off spec,” Van Wyk says.

Contaminated DEF can cause any number of problems with today’s SCR systems, including:

• Increased DEF consumption in equipment

• Loss of its effectiveness to remove nitrogen oxide from engine exhaust

• Malfunctions with the SCR system

• The engine de-rating or shutting down

• Damaged equipment

• Voiding of the manufacturer’s warranty.  

“Equipment using contaminated DEF will consume more fluid and be less effective at reducing emissions from the exhaust, and most importantly, contamination will damage the catalyst in the SCR system over time, potentially causing the engine to shut down and leave the machine idle,” Van Wyk says.

“There are several engine manufacturers now stating that they will opt to decline warranty claims if the damage is tied back to contaminated DEF.”

Van Wyk offers a number of tips for managers and users to protect their assets.

“They should never mix their own DEF, or use small jugs and containers that have been used to previously store other fluids, and the use of older, non-dedicated containers significantly increases the opportunity for DEF contamination,” he says.

“Care should also be given when filling the DEF tank from a smaller container via a funnel, as any other dirt, grease or fluids previously poured through that funnel can contaminate DEF. And the DEF fill area on each machine should also be kept as clean as possible to prevent possible contamination when a DEF nozzle is inserted into the machine,” according to Van Wyk.

And if common elements aren’t enough to worry about, there are the outside elements—as in weather.

“Prolonged exposure to direct sunlight and high temperatures will cause DEF to degrade,” Van Wyk says. “DEF retains its full quality for 36 months when stored at or under average temperatures of 50 F. This reduces to 18 months at 77 degrees, 12 months at 86 F, and just six months for DEF that is consistently exposed to temperatures above 96 F.”

Van Wyk cautions that there are also risks to storage containers and pumping systems if the temperature drops too far (although freezing does not have a negative effect on DEF itself). And winter is coming.

DEF freezes at 12 F, so Van Wyk recommends these guidelines in colder climates:

• DEF expands by approximately 7 percent when frozen. Prevent fully filled, closed containers and pumping systems from freezing, as this can cause damage. This is a benefit of two-in-one pumping systems, as DEF can be easily purged back into the tank after filling the machine.

• Be sure DEF is completely thawed before use.

• Do not use additives to prevent freezing; they can lead to contamination.