If you haven't bought a semi truck in a long time, you may be surprised by the advances in emission control that have been made over the past decade. Today's semi trucks contain sophisticated pollution reduction equipment that you may not be familiar with, and that's why it's a good idea to acquaint yourself with this technology if you are looking to purchase a used commercial truck for sale. Below is information about one such innovation, selective catalytic reduction, and its agent of action, diesel exhaust fluid:

What is selective catalytic reduction?

Selective catalytic reduction (SCR) is technology that works to reduce nitrogen oxide without changing engine performance. The Environmental Protection Agency mandated the adoption of SCR in 2010 for semi trucks, and even light passenger vehicles powered by diesel are now required to use it. However, unlike many other pollution control devices, SCR permits manufacturers to focus on engine performance parameters and maximizing power output. This prevents fuel mileage from dropping and allows semi trucks to operate with higher efficiency.

Selective catalytic reduction and diesel exhaust fluid

Some of the best aspects about SCR are its relative simplicity and low cost. By introducing a chemical called urea to the exhaust stream, nitrogen oxide, which is a notorious pollutant that causes acid rain, is converted into harmless nitrogen gas and liquid water. This process is simple, effective and demands fairly little attention from drivers. In fact, the only thing that most drivers need to do is replenish the urea on occasion; this is accomplished by adding a diluted form of urea known as diesel exhaust fluid. Since this may new information, here are some things you need to know about diesel exhaust fluid:

Diesel exhaust fluid is safe

It is important for truckers to know that handling diesel exhaust fluid is completely safe and poses no health or safety risks. It consists entirely of urea, which is a harmless organic compound, and water. That means you can safely handle diesel exhaust fluid and accidental contact or spillage are of minimal concern.

Diesel exhaust fluid should be kept free of contaminants

For diesel exhaust fluid to react properly with the nitrogen oxide in the exhaust stream, it must be nearly pure; otherwise, the reduction to nitrogen and water won't occur. Equipped trucks monitor the SCR, and failure of the system due to impure diesel exhaust fluid will cause the truck to run poorly or not start at all. Removal of the contaminated diesel exhaust fluid can involve extensive or costly repairs.

That is why you should always keep diesel exhaust fluid in its tightly sealed original container provided by the manufacturer or purchase it at the fuel pumps. Don't leave the lid off the container, and if you suspect it has been contaminated, dispose of the diesel exhaust fluid by pouring it down a drain.

Diesel exhaust fluid is widely available

If you are concerned about finding diesel exhaust fluid, you can rest easy. It is sold by nearly all major stores, truck stops, auto parts stores, and a number of online vendors. In addition, truck stops now supply diesel exhaust fluid in convenient pumps that operate much like conventional diesel fuel pumps. This reduces or eliminates your need to carry your own supplies.

Diesel exhaust fluid is used at a much lower rate than fuel

Diesel exhaust fluid is a consumable, but it is only used at a rate of approximately two or three gallons per 100 gallons of diesel fuel. That means you will need to fill the diesel exhaust fluid reservoir on a semi-regular basis, but it is not going to be a burden to most drivers.