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Diesel Exhaust Fluid Helps Eliminate Nitrogen Oxide Emissions

The Carbis Team | Feb 11, 2013 8:05:00 AM

Diesel Exhaust Fluid or DEF for short is a clear, non-hazardous and non-flammable liquid. It is neither a fuel, nor a fuel additive but it works with Selective Catalytic Reduction systems (SCRs) to reduce nitrogen oxide (NOx) emissions from diesel exhaust. DEF is made up of 32.5% high-purity urea and the rest is de-mineralized water.

The purity of DEF is of the utmost importance. Both the urea solution and the water must be free of any contaminants. A diesel truck manufactured in 2010 or after should have a tank dedicated solely to holding DEF. The tank is filled using a pump similar to refueling a gas tank. If Diesel Exhaust Fluid gets on your hands or clothes it washes off with water.

The main components of a Selective Catalytic Reduction System are:
• SCR catalyst
• DEF injection unit
• DEF tank
• DEF dosing control unit

The system works by injecting the correct amount of DEF into the exhaust pipe in front of the SCR catalyst. Here the heat from engine exhaust gases decomposes the DEF into ammonia. When the nitrogen oxide (NOx) from the diesel fuel reacts inside the catalyst with the ammonia, NOx molecules are converted to nitrogen and water thereby rendering the NOx harmless to air quality.

Why the concern with nitrogen oxide emissions? NOx is an air pollutant that contributes to asthma, respiratory, and heart diseases. The EPA estimates that by the year 2030, the 2010 changes in emission standards will prevent approximately 1.5 million sick days, 8,300 premature deaths, and save an estimated $70 billion.

If your company uses DEF for its truck fleet, ensure that it has the American Petroleum Institute’s (API) certification. To prevent contamination, DEF must be handled carefully. It’s also more likely that DEF will be damaged by materials it touches rather than causing any damage. Pumps and containers used for DEF must never be used for other fluids.

The average shelf life of DEF is two years if the fluid temperature is kept between 12°F (-10°C) and 86°F (30°C). It should be stored in a cool and dry, well-ventilated area, away from direct sunlight. Temporary exposure to high temperatures has little to no impact on DEF quality. However, in hot climates where a truck sees little to no use for extended periods, DEF fluid may need to be replaced since the water will evaporate. When the temperature reaches 120°F DEF slowly converts to ammonia. On the opposite end of the temperature spectrum, DEF starts to freeze around 12°F, so heating lines are needed to keep the fluid from freezing.

Some stainless steels and a few plastics are suitable for storing DEF, but never use copper, copper-containing alloys, carbon steels, or zinc-coated steels. DEF is made in the USA and many suppliers transport it by rail car. With proper loading/unloading equipment from Carbis, your company can, too. Carbis will design proper stainless steel loading arms and other equipment so your company can appropriately transload the fluid keeping it at the highest level of purity. Contact us today at 800.948.7750 and let’s discuss how we can help your company move more product safely and accurately.

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