What is an SCR sensor?
Selective Catalytic Reduction (SCR) is an advanced active emissions control technology system that reduces tailpipe emissions of nitrogen oxides (NOx) down to near-zero levels in newer generation diesel-powered vehicles and equipment.
What is a SCR on a diesel engine?
Selective Catalytic Reduction (SCR) is a proven and advanced active emissions control technology system that injects a liquid-reductant agent through a special catalyst into the exhaust stream of a diesel engine. The reductant source is usually automotive-grade urea, otherwise known as Diesel Exhaust Fluid (DEF).
What does SCR do in an engine?
SCR stands for selective catalytic reduction, which is a technology used for reducing nitrogen oxides (NOx) from the exhaust gas of diesel engines. It’s based on AdBlue® – also called diesel exhaust fluid – a 32.5% urea solution in purified water, which is injected into the exhaust pipe.
Where is the SCR located?
In general, the SCR unit is located between the furnace economizer and the air heater, and the ammonia is injected into the catalyst chamber through an ammonia injection grid. As in other SCR applications, the temperature of operation is critical.
Can SCR be cleaned?
SCR catalyst systems need to be cleaned to remove contaminants and plugs. If the catalyst is not kept clean and the ammonia injection system is not tuned, ammonia slip occurs.
How do I know if my SCR is bad?
Connect the negative lead of your ohmmeter to the anode of the SCR and the positive lead to the cathode of the SCR. Read the resistance value that is displayed on the ohmmeter. It should read a very high value of resistance. If it reads a very low value, then the SCR is shorted and should be replaced.
Can you clean a diesel SCR?
The good news is that SCRs typically require little to no ongoing care or maintenance. Once in place, they should do their jobs without much interference from you. In some cases, the filter will need to be dosed with the chemical reactant it uses to catalyse the reaction with the NOx emissions.
Can SCR box be cleaned?
What does SCR mean on a diesel engine?
Selective Catalytic Reduction (SCR) is an advanced active emissions control technology system that injects a liquid-reductant agent through a special catalyst into the exhaust stream of a diesel engine. The reductant source is usually automotive-grade urea, otherwise known as Diesel Exhaust Fluid (DEF).
What size diesel engine does urea SCR test on?
In another study by FEV and Ford a urea SCR system was tested on a 2.5 liter light-duty diesel engine [206]. Ongoing development of the Ford system has been targeting the US EPA Tier 2 Bin 5 emission limits [983].
Can open loop SCR reduce NOx emissions from diesel engines?
Light-Duty Engines. In an SCR study with a 2.5 liter light-duty diesel engine, NOx conversions of up to 60% on the ECE+EUDC cycle and up to 83% on the FTP-75 cycle were reported [206]. So far, the open loop SCR technology has not been able to reduce NOx emissions to meet the US EPA Tier 2 Bin 5 limit [983].
How does the position of the DPF affect the SCR performance?
If a catalytic DPF is positioned upstream, it can be a source of increased NO 2 levels to enhance the SCR performance. In the upstream position, the DPF is also exposed to gases of higher NOx concentrations, which improve DPF regeneration.