The system in sequence
Store and supply
The approved reagent is held in a compatible tank and fed through the system’s supply equipment.
Dose and mix
The dosing unit meters solution into the exhaust according to the installation’s control strategy.
React over the catalyst
Ammonia derived from urea reacts with NOx to produce nitrogen and water under suitable operating conditions.
Monitor and maintain
The installation’s sensors, alarms and maintenance procedures support the required operating performance.
Why there is no universal dosing rate
Engine load, engine-out NOx, exhaust conditions, catalyst condition and the OEM control map affect consumption. Use the vessel’s documented dosing rate or measured consumption to plan supply; a fixed website multiplier cannot establish a compliant dose.
Avoid unsupported substitutions
Confirm the reagent concentration required by the installation. Off-specification or contaminated fluid and incorrect operating conditions can affect the system. Investigate alarms with the crew and OEM before adjusting dosing on the basis of a general website guide.
Planning tools
AUS40 consumption and supply calculator uses your entered operating and dosing assumptions. For procurement, also review batch documentation and storage guidance.
References
Common questions
How does a marine SCR system work?
Urea solution is stored in a dedicated tank, metered into the exhaust by a dosing unit, and converted to ammonia, which reacts with NOx over a catalyst to form nitrogen and water. Sensors and alarms monitor the process, and the control strategy is set by the installation.
How much AUS40 does a vessel consume?
There is no universal figure. Consumption depends on engine load, engine-out NOx, exhaust conditions, catalyst condition and the OEM control map. Use the vessel’s documented dosing rate or its measured consumption, not a generic multiplier.
Why does my SCR system alarm after a reagent change?
Investigate with the crew and the OEM before adjusting dosing from general guidance. Off-specification or contaminated fluid, wrong concentration and unsuitable operating conditions can all affect the system, and the cause matters.
Does SCR work at all engine loads?
Not necessarily. Catalyst activity depends on exhaust temperature, so low-load operation can fall outside the effective window. The installation’s own documentation defines the operating conditions, so plan reagent consumption around those and not around total running hours.