Fluid for SCR systems. We adhere to environmental standards
Content
SCR is called selective because it is designed to reduce only the dangerous oxides of nitrogen in exhaust gases from diesel engines. The method is very effective, but urea solution becomes an additional filling material.
The principle of the system
Urea through the nozzle enters the exhaust gases after the exhaust manifold to the catalyst. The liquid awakens the decomposition of nitrogen oxides into water and nitrogen - natural substances found in wildlife.
New Environment Commission requirements in the European Union are forcing car manufacturers to control vehicle emission standards and install SCRs on vehicles with diesel engines.
Physical and chemical properties
Liquid for the SCR Adblue system, consists of a solution of water and urea:
- Demineralized water - 67,5% solution;
- Urea - 32,5% solution.
Adblue is located in its own plastic or metal tank, mostly close to the fuel tank. The tank is equipped with a blue cap on the filler neck, has a corresponding Adblue inscription. The filler necks of the urea and fuel tanks have different diameters to eliminate the possibility of a mistake when refueling.
The freezing point of urea is -11 °C, the urea tank is equipped with its own heater. Also, after stopping the engine, the pump in reverse mode pumps the reagent back into the tank. After freezing, the thawed urea retains its working properties and is suitable for further use.
Fluid flow and operating requirements
The average consumption of a working fluid for an SCR is approximately 4% of the consumption of diesel fuel for passenger cars, and approximately 6% for a truck.
The vehicle's on-board diagnostic system controls many parameters of the urea solution:
- level in the system.
- Urea temperature.
- The pressure of the urea solution.
- Liquid injection dosage.
The control unit warns the driver by illuminating the malfunction lamp on the dashboard about the too rapid consumption of the solution and the emptying of the tank completely. The driver is obliged to top up the reagent during the trip. If the system alerts are ignored, the engine power is reduced from 25% to 40% until the reagent is filled. The instrument panel displays the mileage counter and the number of engine starts; after resetting the counter, it will be impossible to start the car engine.
It is necessary to fill liquid for SCR systems only from trusted urea manufacturers: BASF, YARA, AMI, Gazpromneft, Alaska. Filling the tank with water or other liquids will disable the exhaust system.
