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If you read the trade magazines and Web sites, you've probably noticed a lively debate among engine makers on whether to use EGR or SCR methods to meet emissions compliance for NOx reduction. But another important component of emissions reduction — retrofitting existing off-road equipment for Particulate Matter (PM) reduction — doesn't get as much ink. Not to worry, because John Deere has your back.

Diesel Particulate Filter (DPF) technology is the benchmark for reducing particulate matter. Retrofit systems can lower particulate emissions by over 90 percent. By contrast, partial filters reduce particulate emissions by 40 to 60 percent. This compares to the 10- to 25-percent reduction of particulate matter provided by Diesel Oxidation Catalysts (DOC) technology.

Expectations
So, if you've identified a retrofit solution with DPF as an option for your existing iron, you need to know what to expect.

First, vendors of retrofitting devices must attain CARB or EPA verification. Both CARB and EPA have official processes that vendors must follow to confirm emission reduction, durability, and reliability levels. Once a retrofit device has achieved verification, the company must warrant the retrofit and its related vehicle systems.

Your John Deere dealer can help familiarize you with both verified vendors and those currently navigating the verification process, such as Cleaire, Huss, and Nett^®.

You'll also need to be familiar with the PM verification levels that CARB offers: Level 1 verification is for 25 percent, Level 2 is for 50 percent, and Level 3 is for 85 percent reduction. Different levels might be required for different jobs — particularly in bid specs for work in non-attainment zones — so beware.

If you're retrofitting your equipment, it's probably a good idea to do so at Level 3, the highest level possible, because once installed, the device can't be upgraded. If one job calls for Level 2 and you install at Level 2, you'll be out of luck if you the next bid requires Level 3.

My re-generation
After installation, DPFs need to be cleared of particulate matter once a day, or every other day. This process, or "burning off" of particular buildup, is called regeneration.

There are three types of regeneration: passive, active, and stationary. Each method requires a certain temperature to burn off the buildup. Passive regeneration uses the heat normally generated by a working machine. To maximize uptime, John Deere's current generation of equipment uses passive regeneration.

In each instance, the machine must achieve a certain temperature to burn off the buildup. With passive regeneration, a machine is already working hard under load and the high temperatures necessary for regeneration to occur naturally. John Deere is engineering its machines toward the ideal of passive regeneration to maximize equipment uptime.

With active regeneration, high temperatures need to be created within the filter by throttling down or injecting fuel into the filter. That's not always practical on the job.

The third option, stationary regeneration, usually means a machine has to be pulled off a job and put into a forced idle for 15 to 30 minutes to raise the temperature of the air blowing through the filter. Obviously, taking a machine out of service doesn't improve productivity.

Regeneration and interim Tier 4
John Deere is incorporating the necessary technology into its Interim Tier 4 engines to maximize active regeneration — and minimize machine downtime. This technology introduces DOCs, intake throttles, and fuel injection into the exhaust.

While Interim Tier 4 engines and retrofits involve use of the same technologies, there are key differences. Original-equipment manufacturers like John Deere integrate the after-treatment at the factory, while retrofit solutions are usually installed in the field. These bolt-on units may be outside the sheet metal and might negatively affect visibility.

After-treatment on Interim Tier 4 engines is controlled by the engine computer. Retrofit units require a second computer to control retrofit parts.

John Deere engineers are studying retrofit solutions for Tier 2 and Tier 3 machines available from the factory or as field-installed options. Watch this space for more information.

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