Diesel Exhaust Fluid (DEF) is already a reality for trucks, buses, and highway vehicles powered by diesel engines. In 2014, new Tier IV guidelines go into effect for off-road equipment as well. These regulations will affect excavators, bulldozers, skid steers and other commercial construction equipment. Also affected are farm tractors and agricultural equipment, heavy forklifts, and airport ground service equipment. Even diesel powered stationary equipment such as generators, pumps, and compressors will be required to meet emission requirements. To comply with EPA regulations, engine manufacturers are using Selective Catalytic Reduction technology which requires a very precise concentration of liquid urea (DEF) in order to operate properly. The MISCO digital refractometer is the ideal instrument for testing DEF to prevent the use of fluid that is outside expected values. MISCO refractometers meet or exceed the requirements of ASTM D7821 – 12, Standard Test Method for Field Test Determination of Urea Concentration in Diesel Exhaust Fluid (DEF).