How To Fix Scr System Fault Kenworth

Selective Catalytic Reduction (SCR) is an advanced active emissions command applied science organisation that reduces tailpipe emissions of nitrogen oxides (NOx) down to well-nigh-zero levels in newer generation diesel-powered vehicles and equipment. The SCR system involves several components packaged together with other parts of the emissions control system. Each manufacturer has its own variations of the blazon and sequencing of dissimilar components in the system.

SCR system

_{*Schematic is not representative of all manufacturers' approach to achieve most nil emissions.}

SCR is an active emissions command system. Hot frazzle gases period out of the engine and into the SCR arrangement where aqueous urea (known as Diesel Exhaust Fluid, or DEF) is sprayed onto a special goad. The DEF sets off a chemic reaction in the exhaust on a special catalyst that converts nitrogen oxides into nitrogen, water, and tiny amounts of carbon dioxide (CO2), natural components of the air we exhale. The exhaust likewise passes through a particulate filter somewhere in the organization and then is and so expelled through the vehicle tailpipe.

The design of SCR technology is such that it permits nitrogen oxide (NOx) reduction reactions to take identify in an oxidizing atmosphere. It is called "selective" because it reduces levels of NOx using ammonia every bit a reductant within a catalyst system. The chemic reaction is known as "reduction" where the DEF is the reducing amanuensis that reacts with NOx to convert the pollutants into nitrogen, h2o, and tiny amounts of CO2. The DEF is speedily broken downwards to produce the oxidizing ammonia in the exhaust stream.

SCR technology is ane of the most price-constructive and fuel-efficient technologies bachelor to aid virtually eliminate emissions from diesel engines. Since 2011, all heavy-duty diesel fuel truck engines apply SCR applied science to comply with the latest EPA emissions standards.

These standards require reducing particulate thing (PM) and nitrogen oxides (NOx) to near naught levels.

SCR can reduce NOx emissions up to xc% while simultaneously reducing HC and CO emissions by 50-90%, and PM emissions by thirty-50%. SCR systems can too exist combined with a diesel particulate filter to attain even greater emission reductions for PM.

The high efficiency of SCR systems in reducing NOx emissions allows manufacturers to residue engine functioning and maximize fuel economy, while yet achieving near nix emissions. Some SCR-equipped heavy-duty commercial truck operators report fuel economy gains of more than 4%.

Benefits of SCR

SCR has been used for decades every bit a master control strategy for reducing industrial stationary source emissions. Beyond on-highway commercial trucks, some off-road engines and equipment like those used in construction and farming, marine, rails, and power generation as well use SCR systems to comply with EPA'south fourth generation emissions standards, known every bit "Tier iv." These standards require similar reductions in NOx, PM, and other pollutants as from on-highway vehicles. With its superior render in both economic and environmental benefits, SCR is also found in diesel fuel powered pick-up trucks, vans, and SUVs.

SCR systems are active systems. Compared to the passive catalytic converters on gasoline vehicles, SCR systems require replenishing Diesel fuel Exhaust Fluid (DEF) on a periodic basis to ensure emissions system functioning. The need to refill DEF is directly related to vehicle fuel consumption. Failure to refill DEF tanks tin can result in immobilization of the vehicle or machine and a requirement for service.

Diesel Frazzle Fluid (DEF) is a not-toxic fluid equanimous of 32% automotive grade aqueous urea and purified h2o. DEF is available with a diverseness of storage and dispensing methods. Storage options consist of various size containers such as bulk, totes and bottles or jugs. The American Petroleum Institute rigorously tests DEF to ensure that it meets industry-wide quality standards. DEF is sometimes referred to equally AdBlue in Europe and in the U.s..

A nationwide DEF distribution infrastructure is in identify making DEF is readily available in bulk, at retail stores, online and nearly all fueling stations that carry diesel. On-board tanks to store DEF typically range in size from five to 22 gallons and are easily identified by a blue cap and/or labeling "DEF Only." For choice-up trucks and SUVs, the DEF filler port is typically located aslope the fuel filler nozzle area. (SEE Prototype) For heavy duty tractor trailers, the DEF tank is typically aslope the diesel fuel tank on the side of the vehicle near the driver's door. Due to the various nature of off-road engines and equipment, the location of the DEF tank and filler port is variable.

SCR lid in fuel

The DEF tank fill opening is designed to accommodate a DEF make full nozzle but to ensure only DEF is put into the tank. Diesel fuel should never be put in DEF tank and vice-versa. To protect against this misfuelling, a diesel nozzle will not fit into the DEF tank opening. In improver, the DEF tank has a blue lid to differentiate it from the diesel tank which may have a yellow or green fuel cap.

For calorie-free-duty vehicles, DEF refill intervals typically occur effectually the time of a recommended oil change, while DEF replenishment for heavy-duty vehicles and off-route machines and equipment volition vary depending on the operating atmospheric condition, hours used, miles traveled, load factors and other considerations.Typically, DEF consumption is effectually iii% of fuel consumption: (example:100-gal fuel consumption would consume about 3 gallons of DEF).

DEF is an integral function of the emissions control system and must be nowadays in the tank at all times to clinch continued functioning of the vehicle or equipment. Low-DEF supply triggers a series of escalating visual and audible warning indicators to the driver or operator. If the DEF is non replenished, the serial of operator inducements progresses and somewhen can lead to derating the engine and limiting vehicle speed, and ultimately locking out the starting system.

Proper storage of DEF is required to prevent the liquid from freezing at temperatures below 12 degrees Fahrenheit. Most vehicle DEF tanks and dispensing systems accept warming devices.

The U.S. Environmental Protection Agency (EPA) recently announced efforts to develop more stringent tailpipe emission standards for commercial vehicles close to nada through the "Make clean Trucks Initiative." Refinements to SCR systems including dosing strategies, catalyst packaging and location are all likely to be considered as office of future emissions compliance strategies.

DEF is widely available wherever automotive supplies are sold including service stations, convenience stations, major retailers and is also distributed via majority tanker to individual fleet locations. To find a DEF dispensing location, visit Notice DEF.