SHANGHAI – Roads in China and other parts of Asia are expected in coming years to see an increasing number of trucks that are equipped with selective catalytic reduction and which therefore require the use of diesel exhaust fluid.
Operators would be wise to select certified DEFs, an official from the American Petroleum Institute said during a lubricant conference here last week.
There are things that can go wrong if you use a diesel exhaust fluid that is not properly formulated or has not been properly stored, Senior Engineer Dennis L. Bachelder told the China International Base Oils & Additives Conference, which was held in conjunction with the Inter Lubric exhibition. Use a certified DEF brand you can trust.
Selective catalytic reduction is one of several technologies – along with exhaust gas recirculation and diesel particulate filters – used on the most modern trucks and passenger cars to help reduce emissions of pollutants and greenhouse gases. Used first on ships and in large stationary diesel engines, SCR injects the DEF into the exhaust stream in the presence of a catalyst that promotes a chemical reaction turning nitrous oxides into nitrogen, water and small amounts of carbon dioxide.
SCR has for several years been used on almost all new trucks in the United States and Europe. So far it is relatively rare in China and much of Asia, but it is expected to become commonplace as those areas adopt stricter emissions standards.
As a consumable, the DEF must be repeatedly replenished. Known in Europe as Ad-blue and in Australia as AUS32, the fluid is stored in a small tank next to the fuel tank. According to Bachelder, operators risk causing deterioration to the catalyst or malfunction of the SCR system if the fluid does not meet a precise formulation – 32.5 percent urea and 67.5 percent demineralized water.
If the fluid is mixed with water that is not demineralized, youre going to have problems, he said. DEF freezes at 12 degrees F and begins to separate and evaporate above 86 F, requiring temperature controls on the tank in which it is stored.
Bachelder added that DEF proper storage is also important. DEF corrodes aluminum, so it must be kept in plastic or stainless steel tanks. It also must be protected from sunlight and has a shelf-life of one to two years.
API, which is based in Washington, D.C., conducts a program to certify DEFs that comply with ISO 22241, an international standard. Applicants submit paperwork documenting that their fluid is properly formulated, has been tested using acceptable methods and is properly stored and handled by the manufacturer. Marketers meeting those requirements are licensed to display APIs DEF certification mark.