833123 1 Mercury GROMMET

Operating the Engine and the Driven Equipment
Check the gauges and the driven equipment frequently during engine operation under a load. At certain ratings, the engine can be operated for extended periods of time at full load.Partial Load Operation
Extended operation at reduced load (less than 30%) may cause increased oil consumption and carbon buildup in the cylinders. Extended operation at reduced load may also cause fuel to slobber through the exhaust system. This fuel slobber and oil consumption can result in either loss of power, poor performance, or aftertreatment system damage.To maintain engine efficiency and performance, apply a full load each hour or operate the engine at a load that is greater than 30%. These actions will burn excess carbon from the cylinders. Operating the engine at 30% or higher will also keep the aftertreatment system in normal operating condition.Note: Do not idle the engine for longer than 12 hours without loading the engine and maintaining a 30% or higher load on engine.SCR Performance and Hydrocarbons (HC)
Note: Air supply must remain active while the engines are operational. Air supply is used to cool the dosing lance, even if the system is not actively dosing.Diesel engine combustion produces hydrocarbons (HC) in the exhaust gas emissions. Engine HC emissions are part of normal engine operation, and the levels are further reduced with the use of the SCR aftertreatment system. Certain operating conditions (typically, less than 200° C (392° F) SCR Inlet Temperature) such as continuous idle at low engine speeds and/or loads, can cause temporary reduced catalyst performance. Upon immediate return to higher loads, reduced catalyst performance may result in catalyst damage due to rapid increase in exhaust gas temperature.The Marine Engine (propulsion application) and Aftertreatment system can operate safely without risk to the catalyst for 12 hours of continuous idle operation (transmission disengaged from the engine). For Marine Aux/DEP (Diesel Electric Power) applications, the system can operate without requiring the HC release procedure. To operate without HC release procedures, continuous engine load greater than 10% at rated speed must be maintained.While managing SCR Inlet temperature and applying load, your engine system safely removes accumulated HC while gradually allowing the system to return to full available power.The engine system protection strategy is always active during operation. In an emergency this protection can be overridden using the engine protection override feature. Throughout operation, the engine system may experience the following codes:SPN 2434-1 Engine Exhaust Manifold #1 Temperature #1: Low - Most Severe (3)
When SPN 2434-1 is active, this code requires the operator to follow the HC Release Procedure.Level 3 - The Level 3 code indicates that the vessel operator must follow an HC Release Procedure. This procedure is to remove the high HC accumulated on the catalyst and protect the catalyst from damage while allowing the vessel to return to operation without derate. In an emergency the engine protection override feature can be activated to allow full engine power however catalyst damage could occur.SPN 2434-18 Engine Exhaust Manifold #1 Temperature #1: Low - Moderate Severity (2)
If SPN 2434-18 is active, continued idling or low load operation (typically 20% load or less) may result in reduced power capability.Level 2 - The Level 2 code is annunciated to provide the vessel operator or technician a warning to change operation to prevent high HC accumulation, avoid possible derate in power if the low load condition continues, and reduce the potential of catalyst damage. Engine HC Release Procedure must be ran to avoid Level 3 Alarm and derate that reduces available engine power to 50%.SPN 1237-31 Display indication that the customer has overridden the derate using the engine protection override feature.
Thermal Management/Mitigation
Hydrocarbon (HC) Release Procedure
If your Cat Marine Engine and Aftertreatment System are in a Level 2 code situation, then the vessel operator or engineer will need to increase engine load to target a higher exhaust temperature. If your Cat Marine Engine and Aftertreatment System are in a Level 3 code situation, then the vessel operator or engineer will need to increase engine load to target a higher exhaust temperature. For variable speed propulsion applications, targeting a higher exhaust temperature can be accomplished by temporarily increasing engine speed. The HC Release Procedure below will allow the engine to raise engine exhaust temperature and remove the accumulated HC from the catalyst system.For the HC Release Procedure to remove hydrocarbons sufficiently from the catalyst and return to work, the operating schedules are listed below.Note: Times of HC Release Procedure may vary due to differing ambient conditions and vessel design.To perform the HC Release Procedure to remove HC from the catalyst effectively and efficiently, follow the guidelines listed in the tables below.
Table 1
3516 1600/1800 RPM Propulsion Engine
3512 1800 RPM Propulsion Engine
Speed (RPM) SCR Inlet Temperature Time (Min)
800 250° C (482° F) 5
900 345° C (653° F) 5
1100 405° C (761° F) 5
1300 445° C (833° F) 20
Table 2
3512 1600 RPM Propulsion Engine
Speed (RPM) SCR Inlet Temperature Time (Min)
1000 250° C (482° F) 5
1100 300° C (572° F) 10
1200 350° C (662° F) 10
1300 375° C (707° F) 20
Table 3
3512 Marine Auxiliary Engine
Speed (RPM) Power (kW) SCR Inlet Temperature Time
1800 100 220° C (428° F) 5
1800 300 310° C (590° F) 15
1800 600 330° C (626° F) 40