How to handle diesel exhaust fluid

By |  February 13, 2017

Diesel exhaust fluid (DEF) is not new to the construction industry. The first heavy construction equipment with DEF was introduced almost five years ago, and on-road trucks with selective catalytic reduction (SCR) have been on the road for some time now.

What is new is the quantity of DEF now in demand and the influx of equipment hitting the market that requires it.

At Integer Emissions Summit and DEF Forum USA 2016 held in Chicago, current projections put North American DEF consumption at more than 1 billion gallons by 2019 and almost 1.7 billion gallons by 2026. By way of comparison, it’s estimated we’ll consume 617 million gallons in 2016. Much of this growth is being driven by the heavy equipment industry.

Manufacturers of high-horsepower diesel engines, specifically those 75 hp and greater, are using SCR systems to meet emissions regulations. SCR is an aftertreatment technology that sprays DEF into the engine exhaust via a dosing mechanism. This produces a chemical reaction with nitrogen oxide (NOx), converting it to water and nitrogen (completely inert) before releasing it through the equipment’s exhaust pipe.

In this article, we’ll review what heavy equipment owners need to know about purchasing, handling and storing DEF — and why it’s critical to the long-term health and performance of their equipment.

Where and how to purchase

Determining which DEF vendor to work with is as simple as checking labels and making sure you’ve got the right type of container to put it in. DEF is commonly sold in jugs, 55-gallon drums, 275- or 330-gallon IBC totes and in bulk. Equipment owners should always make sure the fluid they are purchasing meets the ISO standard (ISO 22241).

Secondly, they should use a container made specifically for DEF, constructed with materials approved in the ISO standard and sterilized and sealed properly. While the ISO standard allows for open systems for storing DEF, a number of OEMs and industry experts suggest that a closed-fluid path solution is the most practical and effective.

The challenge with open systems is the container must be sterilized between each use, which is not practical in construction environments.

A closed system – where the DEF is never exposed to the elements until the very moment it’s pumped into the machine – ensures fluid purity and machine health.

These systems can be outfitted on more simple storage and handling solutions, such as an ISO-compliant 50-gallon DEF tote. There are also dedicated ISO-compliant DEF trailers and DEF storage and pumping systems built into larger fuel and service trailers. Furthermore, two-in-one pumping systems are available with these solutions that allow DEF to be seamlessly pumped into and out of containers without having to switch to another pump – simplifying the footprint and hassle of these systems.

Equipment owners should not use small jugs and containers that have been used to previously store other fluids. The use of older, non-dedicated containers significantly increases the opportunity for DEF contamination.

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.

Why is DEF purity important?

Photo courtesy of Thunder Creek Equipment and Case Construction Equipment

When DEF is handled properly, there is absolutely no risk to machinery health or performance. Photos courtesy of Thunder Creek Equipment and Case Construction Equipment

DEF is always comprised of 67.5 percent de-ionized water and 32.5 percent automotive-grade urea. This colorless fluid is not hazardous but is highly sensitive to chemical impurities and is corrosive to certain metals such as steel, iron, zinc, nickel, copper, aluminum and magnesium. Maintaining the integrity of DEF is imperative to protect Tier 4 engines.

Less than 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. These 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.

Contaminated DEF can cause any number of problems with today’s SCR systems:
◾ 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. 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. There are several engine manufacturers now stating they will opt to decline warranty claims if the damage is tied back to contaminated DEF.

Shelf life of DEF

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

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). DEF freezes at 12 degrees, so follow these guidelines in colder climates:

◾ DEF expands by about 7 percent when frozen. Prevent fully filled, closed containers and pumping systems from freezing, as this can cause damage. This is another 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 as this can lead to contamination.

Heating elements can also be added to DEF totes and trailers to prevent DEF from freezing when working in cold weather climates.
When DEF is handled properly, there is absolutely no risk to machinery health or performance. By handling DEF in ISO-approved containers and with consideration to environmental conditions, equipment owners will ensure SCR-based Tier 4 engines and systems experience optimal uptime and productivity.

Luke Van Wyk is the general manager for Thunder Creek Equipment.

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