System Of Additional Treatment Of Exhaust Gases; System Of Additional Treatment Of Exhaust Gases (Scr); Conditions For System Scr Operation; Urea (Aqueous Urea Solution Aus 32) - Zetor CRYSTAL Series Operator's Manual

SYSTEM OF ADDITIONAL TREATMENT OF EXHAUST GASES

System of additional treatment of exhaust gases (SCR)

The tractor is equipped with the engine fulfilling emission limits STAGE IIIB.
The compliance with the emission limit is achieved, among others, by injection of the reduction agent (urea)
into the exhaust manifold (SCR) and consequent catalytic reduction in the catalyst of exhaust gases.
Using the SCR system, emissions of NOx (NOx = nitrogen oxides) exhausted by the engine can be
continuously decreased.
At the same time, the reduction agent injected into the exhaust system reacts in SCR catalyst with NOx
emissions contained in exhaust gases which are reduced to nitrogen (N2) and water (H2O).
The control of the injected amount of urea is performed using the engine electronic control.

Conditions for system SCR operation

The amount of urea in the tank is displayed on the instrument panel.
If the amount of urea in the tank is exhausted when the engine is running, the injector in the exhaust
manifold is in danger of being damaged.
In this way also the catalytic reduction is stopped and the amount of harmful emissions in exhaust gases is
increased.
When urea is added in the tank, the catalytic reduction is restored.
Conditions for proper functioning of the system
- temperature of cooling liquid must be higher that 60°C
- working temperature of the catalyst must be higher than 250°C
- outdoor temperature must be higher than -20°C
- engine revolutions must be higher than 1,000 rpm
- requirement for the withdrawn torque must be higher than 20%

Urea (Aqueous Urea Solution AUS 32)

Urea is a highly pure aqueous urea 32.5% solution used as a reducing agent NOx for additional treatment of
exhaust gases SCR of motor vehicles with diesel engines.
The product is labelled as Urea or AUS 32 (AUS: Aqueous Urea Solution) and complies with the standard
ISO 22241-1 Reducing agents NOX AUS 32.
The urea solution AUS 32 is known in USA and North America as Diesel Exhaust Fluid (DEF).
The lifetime of urea without the loss of the quality is influenced by storage conditions.
It crystallizes at ambient temperature of -11°C and at ambient temperature over +35°C it initiates hydrolytic
reaction which means that a slow decomposition to ammonia and carbon dioxide begins.
It is essential to protect unprotected vessels from direct sunlight. Barrel must not be stored longer than one
year! Pay attention to the resistance of the used materials and store vessels. Urea freezes below the
temperature of -11°C.

Principles for safe handling of urea

Contact with skin
- Prolonged or repeated contact may cause skin irritation.
Contact with eyes
- Prolonged or repeated contact may cause eye irritation. Rinse eyes with plenty of water for at least 15
minutes. If irritation persists, visit a physician.
Ingestion
- In case of ingestion of small quantities, toxic effects are not likely. Higher amount may cause intestinal or
stomach problems. Do not induce vomiting. Drink half a litre of water or milk. In case of ingestion of a larger
than small quantity, visit a physician.
Fire-fighting measures
- The product has fire extinguishing properties.
Extinguishing means
- If the material got in the fire, use large amount of water for extinguishing.
Accidental release measures
- Minimize contact of the spilled material with the soil so that you do not allow product to reach surface or
underground water courses.
- Soak up the spilled material with dry soil, sand or other non-flammable material.
65