Total CLEARNOX: Stop crystallisation in machines to improve SCR effectiveness

CLEARNOX is applicable for all on-road and off-road vehicles or machinery equipped with selective catalytic reduction (SCR) technology.

SCR is an after-treatment technology of exhaust emissions from diesel engines that is proven to be one of the most efficient solutions to meet the latest nitrogen oxides (NOx) emissions standards.

Total’s researchers have worked with engine and vehicle manufacturers to develop CLEARNOX, which is a ready-to-use urea solution according to stringent industry standards to address the unwanted crystallisation issues.

To comply with the stringent Euro or environmental protection authority (EPA) emission standards, majority of vehicle manufacturers have installed pollution control systems across their vehicles and heavy-duty machinery based on SCR technology using AdBlue.

AdBlue is an aqueous solution made up of 32.5 per cent high purity urea and 67.5 per cent deionised water, and is used to clean the exhaust gases (NOx) of diesel engines within the SCR system. It is injected into the exhaust system which then results in a chemical reaction forming ammonia (NH3).

Hereafter, inside the SCR system, ammonia formed will react with NOx from the exhaust gas, which is then transformed into harmless nitrogen (N2) and steam (H2O) before being emitted into the environment.

However, under certain operating conditions, the temperature of exhaust gases may not be sufficiently high enough for a complete reaction to occur with AdBlue. For example, vehicles and machinery operating in cold weather or operating with frequent stop/start and idling conditions.

This will lead to the formation of cyanuric acid crystal deposits at the inlet to the SCR system. The pollution control systems can therefore be fouled by these crystals, bringing the vehicle to a standstill and causing a need for servicing.

Such immobilisation can be costly to operations.

How CLEARNOX works

CLEARNOX is a ready-to-use urea solution complying with the physical and chemical specifications according to ISO 22241-1 standard and is recommended for use as a direct substitute for AdBlue.

Thanks to proprietary additives, CLEARNOX takes the chemical process a step further than AdBlue by guaranteeing an optimal urea spray for complete reactions even at lower temperatures, thus preventing crystallisation and helping the SCR system to work more effectively.

This keeps vehicles in operation and eliminates the risk of unscheduled downtime.


For optimal SCR system operation, first time users should have their vehicle’s SCR system cleaned at a certified auto repair centre before starting the use of CLEARNOX. This will enable the maximum benefits of CLEARNOX to be realised.

CLEARNOX is useful for all on-road and off-road vehicles equipped with SCR technology including city buses, short-haul trucks, tractors, construction machinery, etc.

Want to stop crystallisation in your vehicles for good? Do not hesitate further and contact your nearest Total affiliate to find out more. 

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