Printable version: G-Drive Ultra Low Emissions FAQ
Tier 4 Interim Emission Regulations
1. What are Tier 4 Interim emission standards?
Tier 4 Interim is the U.S. Environmental Protection Agency (EPA) emission regulations for off-highway diesel engines in North America.
The regulations went into effect January 2011 across the 174 to 751 hp (130-560 kW) power category, requiring diesel engines to reduce PM exhaust emissions by 90% and NOx exhaust emissions by 45% compared with the current Tier 3 emissions standards.
The emissions standards for this power category are 2.0g/kW-hr Oxides of Nitrogen (NOx) and 0.02 g/kW-hr Particulate Matter (PM).
2. What is the Tier 4 Final standard in 2015?
Beginning in 2015, EPA Tier 4 Final will require another major emissions reduction for diesel engines from 75 to 173 horsepower, both NOx and PM exhaust emissions will be reduced by 90% compared with current Tier 3 levels.
The emissions standards for this power category are: 0.4g/kW-hr Oxides of Nitrogen (NOx) and 0.02 g/kW-hr Particulate Matter (PM) effective January 2015. These extremely low levels can be described as ‘near-zero’ emissions levels.
3. What are Oxides of Nitrogen (NOx) and Particulate Matter (PM)?
Oxides of nitrogen are a regulated gaseous emission which is a collective term for emissions composed of nitrogen and oxygen. Particulate matter is a regulated diesel emission composed primarily of carbon soot and other combustion by-products.
4. When will engines from 74 hp to 751 hp need to meet the low emissions regulations?
We can divide the Engine range from 74 hp to 751 hp in two power categories for emissions purpose: Engines below 173 hp and engines above 173 hp.
For engines within the 75 hp to 173 hp (56-129 kW) power category, Tier 4 Interim went in to effect January 2012. The Tier 4 Final regulations will be applied in January 2015. Emissions levels are less severe for this power category at Tier 4 Interim, enabling a more simplified aftertreatment system.
For engines within the 174-751 horsepower (130-560 kW) power category, Tier 4 Interim regulations went into effect in January 2011. The Tier 4 Final regulations will be applied in January 2014. Emissions reductions are more stringent for this 174-751 horsepower category at Tier 4 Interim, which require Cummins to use a different solution.
Meeting Emissions with the Right Technology
5. How will Cummins meet the Tier 4 Interim emissions standards for 74-751 hp range?
Cummins QSB5 engine will meet the 2012 low emissions standards with an integrated Cummins Compact Catalyst exhaust aftertreatment and a cooled exhaust gas recirculation (EGR) system incorporated on the engine. The cooled EGR system enables clean combustion with NOx reduced by over 30% compared to Tier 3, while the Cummins Compact Catalyst exhaust aftertreatment system reduces PM by over 90% from engine exhaust.
Cummins QSB7, QSL9, and QSX15 engines are meeting the 2011 low emissions standards with an integrated Cummins Particulate Filter exhaust aftertreatment and a cooled exhaust gas recirculation (EGR) system incorporated on the engine. The cooled EGR system enables clean combustion with NOx reduced by 45% compared to Tier 3, while the Cummins Particulate Filter exhaust aftertreatment system reduces PM by over 90% from engine exhaust.
6. Does Cummins design their own aftertreatment and other key systems?
Yes. We design the Cummins Particulate Filter as an integrated system with the engine. Meeting Tier 4 Interim demands new levels of system integration in order to achieve very low emissions while improving performance. Cummins has access to all the key enabling technologies within our design and manufacturing resources, from aftertreatment, fuel systems, filters and electronic control to turbocharging. This forms the basis of our ‘Right Technology’ approach to Tier 4.
7. Why is Cummins Tier 4 Interim approach better than others?
We believe Cummins has significant advantages over other engine manufacturers. We design, manufacture and integrate the complete Tier 4 Interim package from air-intake to exhaust aftertreatment. Only Cummins has all the key enabling technologies in-house and can therefore realize more effective integration with packaging and performance advantages. In addition, Cummins has acquired unrivalled experience of using this technology by successfully meeting EPA 2007 on-highway standards. High performance and reliable technology drove a major increase in our market share since 2007.
8. Has the Cummins Particulate Filter aftertreatment been used before?
This technology was new to the off-highway equipment industry in 2011 – but it is not new to Cummins. Cummins introduced on-highway engines in 2007 certified to EPA standards in North America using both cooled EGR and the Cummins Particulate Filter. Our experience of using EGR extends back to 2002. Cummins capability with this technology is unmatched in the industry, reflected in these production figures by the start of 2011:
-EGR engines produced: Over one million
-Particulate filter aftertreatment systems produced: 650,000 -XPI systems produced: 100,000
-VGT™ Turbochargers produced: Over three million.
9. Will Tier 4 Interim engine performance is the same as Tier 3?
It will be better. Cummins Tier 4 Interim engines have demonstrated up to 5% improved fuel efficiency compared to Tier 3, depending on rating and duty cycle. Tier 4 Interim equipment productivity is also enhanced with faster engine response. Operators will also notice that Cummins Tier 4 Interim technology enables the equipment to work cleaner and quieter than before. And while CO2 emissions are not regulated by the EPA, Cummins fuel efficiency improvement at Tier 4 Interim translates into reduced CO2 emissions, helping our customers reduce their carbon footprint at Tier 4 Interim.
10. How will Tier 4 Interim impact the cost of equipment?
Achieving very low levels of emissions for Tier 4 Interim has required a major investment in engine technology and involves the addition of systems such as Cummins Compact Catalyst aftertreatment. The cost of the equipment will therefore reflect the incorporation of a Tier 4 Interim technology system and in some cases more advanced cooling packages.
While Tier 4 Interim powered equipment will be inherently more expensive than Tier 3 equipment, the cost of achieving compliance will be helped by the lower overall operating costs offered by Cummins Tier 4 Interim engines.
11. Why is Selective Catalytic Reduction (SCR) less effective than cooled EGR and Cummins Compact Catalyst for Tier 4 Interim?
As part of Cummins Tier 4 Interim evaluation program, various combinations of Cummins Particulate Filter or Cummins Compact Catalyst with cooled EGR and SCR were extensively tested as possible technology paths. However, our development work proved that a Cummins Compact Catalyst in combination with cooled EGR provides the most effective Tier 4 Interim solution. This solution will achieve the best operating value for our customers. It offers equivalent, or better fuel efficiency compared with using an SCR system for off-highway applications. An additional consideration was that SCR requires regular refilling of an on-board Diesel Exhaust Fluid (urea) tank. Operators of off-highway equipment have consistently expressed a preference to avoid the additional cost, supply and refilling of Diesel Exhaust Fluid for an SCR system. Cummins cooled EGR and Cummins Compact Catalyst does not require this additional fluid.
12. Is SCR a technology option for Tier 4 Final?
SCR is the incremental technology employed by Cummins to meet Tier 4 Final Emissions. Cummins knows SCR technology better than any other engine manufacturer. In 2006, Cummins launched its on-highway engines certified to the Euro 4 standard using SCR in Europe with over 350,000 of these systems in operation.
Cummins Compact Catalyst
13. Why does Cummins use the Cummins Compact Catalyst at 173 horsepower andbelow – but not for engines 174 horsepower and above?
Cummins provides value by offering the right technology for the right equipment. As maintenance free, “fit and forget” system, the catalyst is ideally suited for compact equipment, typically used in the rental market. The Cummins Compact Catalyst also provides a simplified and flexible system installation for Tier 4 Interim, a key requirement for space constrained equipment below 174 horsepower. Equipment with engines above 173 horsepower has more installation space and also needs to meet more stringent emissions regulations, which makes the Cummins Particulate Filter an ideal solution.
14. Has the Cummins Compact Catalyst aftertreatment been used before?
This technology is new to the off-highway equipment industry – but it is not new to Cummins. Cummins has been manufacturing Diesel Oxidation Catalyst technology since 1994 for on-highway bus applications, representing over 15 years of experience and a very high volume population in North America.
15. How does the Cummins Compact Catalyst remove PM?
The catalyst removes PM by a process of simple, passive oxidation.
16. Does the catalyst impact the operation of the machine or require any user intervention?
No. The catalyst operates automatically and is transparent to the operator and does not impact equipment performance.
17. Does the catalyst create more noise or heat compared to a muffler?
The catalyst will not create additional noise or heat compared with a standard muffler. The maximum skin temperature of the catalyst will be no higher than that of today’s muffler.
18. Is an exhaust muffler also required?
Yes. Noise attenuation is still required. There will be options to purchase a Cummins Compact Catalyst without a muffler or with an integrated acoustic catalytic muffler. An integrated acoustic catalytic muffler would be somewhat smaller than a Diesel Particulate Filter, but installation flexibility is the key advantage with the option of separating the catalyst and muffler.
19. Does the catalyst need to regenerate, like a Diesel Particulate Filter (DPF)? Does it ever need to inject fuel in the exhaust to function?
No. The catalyst does not operate by either passive or active regeneration, which is typical of a Diesel Particulate Filter. The catalyst works by a simpler process of continuous passive oxidation of the PM as it flows through the system. This oxidation is initiated by the normal temperature of the exhaust. No additional fuel injection is needed to increase this temperature.
20. Is it really a “fit and forget” device? Yes. Once installed the catalyst requires no user intervention or maintenance.
21. Why doesn’t the Compact Catalyst require ash cleaning?
It doesn’t require ash cleaning because it is a flow through device that does not capture ash. A DPF does require ash cleaning because it is a wall flow filter.
22. Will fuel sulfur content higher than 15-ppm damage the catalyst?
An oxidation catalyst can tolerate diesel fuel sulfur up to 500-ppm. However, using 15-ppm fuel is the legal requirement for meeting EPA Tier 4 Interim and EU emission regulations.
However, improper fuel use of sulfur levels greater than 15-ppm with Cummins Tier 4 Interim engines can permanently damage other aftertreatment components.
23. How does the Cummins Compact Catalyst differ from a typical Diesel Oxidation Catalyst (DOC)?
Cummins Compact Catalyst represents the latest evolution of diesel oxidation technology specifically designed for Tier 4 Interim emissions and off-highway applications. The catalytic coating and substrate is unique to the QSB5 and QSB7 to provide optimum performance
24. What will the catalyst cost?
We supply the catalyst as part of a fully integrated system with the engine, leading to a competitive system price that offers superior value to the end customer and OEM.
Cummins Cooled EGR System and VGT™ Turbocharger
25. How does cooled EGR reduce NOx emissions?
Cummins utilizes cooled EGR to effectively control NOx emissions. Cooled EGR works by re-circulating a varying proportion of the exhaust gas back to the cylinder. This reduces the oxygen content to a lower combustion temperature resulting in a reduction of NOx formation.
The exhaust gas is cooled as it flows through an EGR cooler, and then is mixed with the compressed fresh air from the turbocharger before entering the intake manifold. As the exhaust gas moves through the intake, the EGR reduces the amount of in-cylinder oxygen available for combustion while maintaining the same amount of air flowing through the engine. Exhaust gases present during the start of combustion are very stable and have a very slow reaction rate. They absorb heat during combustion, resulting in lower in-cylinder peak flame temperatures, and therefore, lower NOx emissions.
26. What are the key components of the EGR system?
The key components to the Cummins cooled EGR system are: EGR Valve, EGR cooler and either a Variable Geometry Turbocharger (VGT™) or Variable Flow Turbocharger depending on the horsepower. A schematic of the system is shown below:
27. How does Cummins VGT™ Turbocharger improve performance?
Cummins VGT™ Turbocharger has a patented one-piece sliding nozzle design that provides exact boost across the operating range. The sliding nozzle varies the exhaust gas Flow into the turbine wheel to provide rapid boost at low engine rpm and then maintain high boost at higher rpm.
The VGT™ Turbocharger design combines the benefit of both a small and large turbocharger in a single unit, enabling Cummins Tier 4 Interim to achieve significantly improved response compared to a Tier 3 engine demonstrated in customer field tests.
Manufactured by Cummins Turbo Technologies, the VGT™ Turbocharger is a key technology asset in not only meeting emissions but increasing engine performance and improving fuel efficiency. Introduced with Cummins on-highway EGR engines in 2002, total VGT™ Turbocharger production is over three million units, demonstrating outstanding in-service reliability.
28. How does Cummins Variable Flow Turbocharger improve performance?
The Variable Flow Turbocharger drives cooled EGR and improves boost across a wider engine speed than our previous wastegate turbocharger to preserve transient response and low end torque. This turbo is proven with both high reliability and a simple mechanism variable turbine with both an inner and outer section. This simple turbine allows for lower complexity and fewer moving parts, which leads to higher durability.
The Variable Flow Turbocharger is integrated by Cummins and driven by Cummins electronics. At low speeds the valves is closed and exhaust gas Flows into the inner section increasing boost pressure. At high speeds the turbo valve is modulated with integrated controls to allow exhaust gas to flow into both the inner and outer sections of the turbo.
Cummins Particulate Filter Aftertreatment
29. How does the Cummins Particulate Filter remove PM?
Cummins Particulate Filter in most cases replaces the Tier 3 muffler and provides equivalent or better sound reduction compared to Tier 3 mufflers. The Cummins Particulate Filter consists of four sections: an inlet, a Diesel Oxidation Catalyst (DOC), a Diesel Particulate Filter (DPF) and an outlet.
Exhaust flows out of the engine and into the Cummins Particulate Filter. It passes through the DOC and then into the DPF where PM is collected on the walls of the DPF. The carbon collected is then oxidized to remove it from the DPF. This is known as regeneration.
When operating conditions maintain sufficient exhaust temperatures, the DPF is continually self-regenerating, over 99% of the time. This is known as passive regeneration and results in clean exhaust out of the tailpipe. On very infrequent occasions, less than 1% of the time, an active self-regeneration is required to remove a build-up of PM in the DPF, due to insufficient exhaust temperatures.
30. What is passive regeneration?
Cummins engines are designed to maximize the use of passive self-regeneration. This occurs when operating conditions maintain sufficient exhaust temperature; therefore enabling continuous oxidation of the PM. Passive self-regeneration is completely transparent to the operator and does not affect the machine’s operation or performance.
Cummins field test results have shown that most off-highway equipment operates at a high enough engine load factor for the Cummins Particulate Filter to self-regenerate almost every time in passive mode.
31. What is active regeneration?
Active self-regeneration occurs when there is not sufficient heat in the exhaust to convert all the carbon being collected in the DPF. Exhaust temperatures are raised by injecting a small amount of fuel upstream of the Cummins Particulate Filter. The resulting chemical reactions over the DOC raises exhaust gas temperatures high enough to oxidize the carbon from the filter. This is all done without any operator intervention. Cummins Tier 4 Interim system is designed to minimize the need for active self-regeneration.
The overall fuel consumption increase due to active regeneration of the particulate filter is barely measurable – approximately 0.1% for most applications. Cummins field tests have proven the majority of active regenerations will be less than 1% of the total operating time. This minor increase resulting from active regeneration is included within Cummins overall Tier 4 Interim fuel efficiency improvement of up to 5%.
32. What is a stationary regeneration?
Stationary, or parked, regeneration is the same as active regeneration but takes place while the equipment is not being operated. It offers the equipment operator the option, if needed, of performing regeneration outside the normal duty cycle. Using this option may only be required in a very limited number of applications. The G-Drive calibration was design to allow enough active self-regeneration to convert accumulated carbon in the DPF without operator interface even at low load operation.
33. Does the Cummins Particulate Filter get hotter than a typical muffler during active regeneration?
Active self-regeneration takes place typically less than 1% of equipment operating time. The skin temperature of the Cummins Particulate Filter, which is double-thermally insulated, is actually lower than the muffler skin temperature of today’s Tier 3 powered machines.
34. What new filtration systems are used on Cummins Tier 4 Interim engines?
Engine filtration enhancements include a new Cummins Direct Flow™ air cleaner and Cummins crankcase ventilation system with a highly-efficient coalescing filter, both manufactured by Cummins Filtration.
35. How is Cummins Direct Flow™ air cleaner different from other air-intake filters?
The new Cummins Direct Flow™ air cleaner was specifically developed for Tier 4 Interim to provide more performance in less space. The rectangular, low profile design can reduce space claim compared with typical cylindrical filters used for Tier 3. Air Flow to the engine is improved and the highest levels of protection are assured with virtually 100 percent efficiency over the filter life.
36. Can Direct Flow™ extend filter change intervals?
The increased air flow efficiency of the Direct Flow™ air cleaner offers operators the opportunity to extend air filter element service intervals and potentially reduce air cleaner filter costs.
37. How does the crankcase ventilation filter improve the engine?
Tier 4 Interim requires that crankcase emissions, also known as blowby gases, be included in the overall regulated engine emissions. To control blowby gas emissions, Cummins engines incorporate a highly efficient coalescing filter. The filter returns the oil to the crankcase and provides the added benefit of removing oil mist and tiny oil droplets, ensuring that the engine and powertrain remain cleaner than at Tier 3. The crankcase filter requires a simple filter element change at 2,000 hour intervals.
38. How does the Electronic Control Module (ECM) differ from Tier 3?
The Tier 4 Interim engine management system is significantly upgraded with the latest Cummins CM2250 electronic control module providing 3 times faster processing power and double memory capacity compared to the Tier 3 module.
Cummins has a unique advantage in that we design the core programs and algorithms needed to precisely control the system from air-intake to exhaust aftertreatment as a single integrated system.
Cummins latest generation CM2250 electronic control module will be incorporated on all Tier 4 Interim engines to ensure electronic commonality across equipment ranges.
39. Will electronic diagnostic tools change for Tier 4 Interim?
Cummins popular and easy-to-use electronic diagnostic tools such as InSite™ software and QuickCheck™ handheld device are already upgraded and available for use with Tier 4 Interim engines and aftertreatment.
40. Will Tier 4 Interim equipment uptime remain the same as Tier 3?
Yes. Cummins Tier 4 Interim field test program has demonstrated that our Tier 4 Interim engines are able to achieve the same very high level of uptime availability as equipment powered with our current Tier 3 engines.
41. What service does the Cummins Particulate Filter require?
The Cummins Particulate Filter is service-free up to 5,000 hours when low ash oil is used and the base engine is properly maintained. At that point, ash cleaning is required. The EPA has set minimum ash cleaning intervals of 4,500 hours for engines 174 hp (130 kW) and above. Cummins expects to reach 5,000 hours before ash cleaning is required.
42. What causes ash in the Particulate Filter?
Ash is incombustible material derived from the additive pack in the lube oil. All engines consume a small amount of oil as part of their normal operation. The oil is burned in the combustion chamber along with the fuel, and the resulting small amount of residual ash from the oil is trapped in the filter section of the aftertreatment system. During filter regeneration, the PM is oxidized and removed from the filter. However, ash from the lube oil cannot be oxidized and remains in the filter.
43. How is the Cummins Particulate Filter serviced?
The Cummins Particulate Filter must be removed and cleaned by a Cummins approved cleaning method and authorized technician. The ash cleaning process typically takes 30 minutes, plus the time to remove the Cummins Particulate Filter from the equipment.
44. What is the life of the Cummins Particulate Filter?
The Cummins Particulate Filter is designed to last the life of the engine. The aftertreatment is specially strengthened against high levels of vibration and shock loading.
45. Is low ash lube oil required for Tier 4 Interim?
Yes. To maintain regulated ash cleaning intervals it is strongly recommended to use API CJ-4 low ash lube oil in North America and equivalent ACEA-E9 lube oil in the EU.
46. Is ULSD fuel legally required for Tier 4 Interim engines?
Yes. In North America, Ultra Low Sulfur Diesel (ULSD) is legally required for Tier 4 Interim engines. The ULSD must contain 15 parts-per-millions (ppm) or less sulfur content.
47. Will ULSD be available outside of North America?
Availability of ULSD is very limited outside of North America and the European Union.
48. Could today’s greater than 15-ppm fuel be used in Tier 4 Interim engines?
Tier 4 Interim engines must use ULSD. It is not possible to comply with the legally required PM emissions standard with today’s off-highway fuel which has higher sulfur content.
49. What happens if higher sulfur fuel is inadvertently used?
A one-time inadvertent tank of diesel fuel with greater than 15-ppm sulfur content will not damage the engine and aftertreatment system. The system will clean itself out when ULSD is re-introduced.
However, continued improper fuel use of sulfur levels greater than 15-ppm with Cummins Tier 4 Interim engines can permanently damage the engine and aftertreatment systems. This damage could possibly cause the engine to be inoperable and cause unplanned downtime and expenses.
50. Can ULSD be used in Tier 3 or other engines?
Yes. Tier 3 and other emission level engines will work fine on ULSD. It is backwards compatible.
51. When will ULSD fuel be available?
ULSD is available today. ULSD was widely introduced in North America in 2006 and more recently in the European Union for emission compliant on-highway engines.
52. Can biodiesel fuel be used with Cummins Tier 4 Interim engines?
Cummins Tier 4 Interim engines are compatible with Biodiesel blends up to B20 as long as the fuel does not exceed 15-ppm sulfur content.
53. Does Cummins Tier 4 Interim technology change the current warranty coverage?
Cummins current engine warranty will become a broader engine and system warranty for Tier 4 Interim by incorporating the exhaust aftertreatment and Direct Flow™ air cleaner housing. The warranty hours, terms and conditions remain unchanged for Tier 4 Interim.