The MISCO DEF-201 refractometer is the ideal method for testing and monitoring the concentration of urea-based Diesel Exhaust Fluid (DEF or AdBlue) required by diesel engines equipped with Selective Catalytic Reduction (SCR) technology. This refractometer has a single scale for DEF concentration.

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. 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). Even concentration variations of as little as +/-0.8% will prevent a DEF fluid from meeting the specifications mandated by International Standards Organization (ISO). DEF dilution or contamination can impact system performance and maintenance costs. The biggest contamination threat is water dilution but without the proper tools it is nearly impossible to know if a DEF supply has been diluted.