Frequently asked questions

Here are the answers to some of the most frequently asked question about the two emission control technologies, SCR and CEGR. If you have any other questions, please submit them so we can complement this FAQ with answers to the questions you and others may have. Naturally, you are also welcome to contact us directly.

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The SCR system and DEF (Diesel Exhaust Fluid)

What is DEF?

DEF is a key component for NOx reduction in the SCR system. DEF is comprised of about 33% urea and about 67% deionized water. Urea is used in a number of different industrial processes, such as in agricultural fertilizers.

Is DEF poisonous?

No. DEF is classed as non-poisonous, non-polluting, and non-flammable. DEF is also completely colorless and odorless, but mildly corrosive.

What role does DEF have in the SCR system?

DEF is added to the exhaust gases before they enter the catalytic converter. In the catalytic converter, the DEF reacts with the environmentally-hazardous nitrogen oxides and converts them into harmless nitrogen and water vapor.

How much DEF is used?

This varies depending on the load, but on average DEF comprises about 3-5% of total fuel consumption.

How large is the DEF tank and how often does it need to be refilled?

The DEF tank holds about 30 liters, 8 liters of which comprise a reserve. The DEF tank is dimensioned to always be filled each time the machine is refueled with diesel.

Can DEF freeze?

DEF has a freezing point of -11°C. However, freezing of both the tank and the injector system is managed in Komatsu Forest's SCR system by emptying the system when the machine is turned off and by using the machine's coolant system to heat the supply lines and DEF tank when necessary. The DEF tank is also designed to freeze without incurring damage. Furthermore, the system has been tested and evaluated in extreme cold without any problems.

Can the machine be operated even if the DEF tank is empty or has frozen?

Yes. The machine can be run for about 40 minutes before the system must operate in accordance with emission requirements, which requires DEF in liquid form in the tank. Sensors monitor this, and such sensor-based monitoring is a requirement for all other systems on the market as well to ensure they are functioning.

Does the DEF and SCR system require any special service?

No, all that needs to be done is to refill with DEF every time you refuel to ensure system functionality, and a simple filter change in the pump module about once every 1,250 hours.

Is the DEF and SCR system sensitive to lower quality diesel (sulfur)?

Yes, but to a much lesser extent than the CEGR system.

The CEGR system and DPF (Diesel Particulate Filter)

What does the EGR valve do?

The valve's role is to adjust the amount of exhaust gases returned to the combustion process. The valve plays a very important role in the system and is sensitive as it must function under poor conditions, such as in the presence of many particulates and so on.

What is the DPF and what does it do?

The DPF is the filter required by the CEGR system to fulfill legal requirements for the reduction of particulate matter (soot). This is due to the insufficient particulate reduction in the combustion process of a CEGR system, due to the low combustion temperature to reduce NOx content already during the combustion process.

How is the DPF prevented from being clogged by particulate matter?

The DPF is regenerated.

How is the DPF regenerated?

Regeneration takes place in two steps. Step one is managed by the operator together with the system. The system detects when regeneration is needed and the operator activates the function within an interval determined by the system. Step two requires that the filter is dismantled is sent away for regeneration, or that a new or replacement filter is fitted.

How long does regeneration take?

Usually a few minutes.

What temperature is reached during regeneration?

From 400ºC up to 700ºC, which in the forest entails an increased fire hazard.

Is the need for regeneration constant or does it vary?

It varies depending on the power output of the engine.

What is the service life of a DPF and what other service requirements does DPF/CEGR entail?

The DPF must be replaced after extended use. Filter replacement and cleaning is conducted by specialist workshops/service providers. How often the filter needs replacing depends on the average workload of the engine. The more often the engine is left idling or operated at low speed, the more frequently the DPF needs replacing. The less effective particulate combustion of the CEGR system causes greater engine oil contamination, which means that the engine oil may need to be changed as often as every 250 hours. Since CEGR technology requires considerably greater engine cooling, service is also complicated by the cooling unit.

Is the DPF and CEGR system sensitive to lower quality diesel (sulfur)?

Yes, the component parts of the CEGR system are more sensitive to poor quality diesel. That is, diesel with high sulfur content.