In 2007, semi truck and engine manufacturers began installing DEF fuel tanks in order to meet federal emissions regulations that went into effect in 2010. The new technology, called selective catalytic reduction (SCR), is an aftertreatment that is injected in small amounts into a diesel engine’s exhaust stream. DEF stands for Diesel Exhaust Fluid. The exhaust stream, which is hot, vaporizes the DEF to form ammonia and carbon dioxide, which is passed over a catalyst and converted into nitrogen and water, which is harmless.
DEF is kept in a separate reservoir tank. DEF is composed of 32.5% high-purity urea and water. Urea is a compound of organic nitrogen that is used commonly in agriculture for fertilizer.
The SCR technology not only reduces pollution, but also saves on fuel. Since the engine no longer has to be tuned to reduce the toxic NOx, it can be adjusted for better fuel economy.
The fuel tank on your truck that has the blue cap is called the DEF fuel tank. When you remove the blue cap, you will notice there is a smaller opening than what’s on the diesel fuel tank. If at all possible, when you go into the commercial card lock or the truck stop try to get bulk DEF fuel. You don’t want to have to deal with the small jugs or containers. The smaller jugs require a funnel and are not as convenient as purchasing it in bulk. Some truck stops will only carry it in the smaller containers, but if at all possible it is best to purchase in bulk.
Once full, a DEF fuel tank will last for about six fills on diesel fuel. So you don’t have to fill it every time you refuel. Just make sure you check it regularly to ensure you don’t get stuck and end up having to use the messy jug system.
There are two fuel gauges on the dash of your rig. One is for the diesel fuel and the other one is for the DEF tank. Keep an eye on your dash gauges so you don’t run into a situation where you get too low.
The biggest concern when it comes to storing DEF is the possibility of contamination. Although DEF is non-toxic, non-polluting and non-flammable, it has to be kept in a plastic container to avoid corrosion. It also has to be kept in a temperature-controlled location and out of direct sunlight. It can be kept for years when stored properly.
If you need to store DEF, here are a few tips to safeguard it from contamination.
- Do not refill previously used containers.
- Be sure to insert the DEF nozzle into the tank’s inlet to avoid contaminating the spout.
- Use only dedicated DEF equipment for storing and dispensing. Do not use funnels or containers that have been used for other purposes.
- Do NOT use tap water if you need to rinse the fueling equipment. You must use de-mineralized water.
- Keep DEF away from substances such as oil, grease, water, dust, fuel, dirt, metal or detergent.
Diesel engines and systems operate better using SCR technology and fleets appreciate the fuel cost savings the DEF system offers. Cline Wood represents top trucking insurance carriers across the U.S. To learn more about the issues that concern commercial truck companies today, trucking coverage and risk management, contact us.
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