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DPF vs. DOC: An Overview On Aftertreatment System Filters

Written by Jimmy Rustling

Like other vehicles, a diesel-powered truck requires proper maintenance to keep it running safely and smoothly on the road. One of the essential things to watch out for in diesel vehicles is the harmful chemicals that may cause problems to the emissions system. This is where a diesel vehicle’s aftertreatment system fits in the picture.  

Generally, the aftertreatment system comprises the Diesel Particulate Filter (DPF) and the Diesel Oxidation Catalyst (DOC). These effective filtration systems for diesel exhaust are responsible for reducing the harmful chemicals and other particulates emitted to the environment. Also, it’s essential to know that DPF and DOC filters are similar and different in some ways.  

Hence, here’s an overview of these aftertreatment system filters that you should get familiar with.  

What Is A DPF Filter? 

A Diesel Particulate Filter or DPF refers to a device designed to minimize the toxic emissions from diesel exhaust. It works by trapping more or less 90% of particulates from the exhaust pipe and preventing it from being released into the environment.  

Since it’s part of the exhaust system, a DOC filter is positioned before the exhaust pipe and after the temperature sensor.  

What Is A DOC Filter? 

A Diesel Oxidation Catalyst or DOC filter refers to a device used to break down chemicals and pollutants into the diesel exhaust into less hazardous components before being released into the environment. It works by converting harmful chemicals into carbon dioxide and water through oxidation.  

Regarding its location, a DOC filter is usually situated before the DPF filter in the aftertreatment system.  

DPF vs. DOC: What Are The Differences And Similarities? 

Now that you know what DPF and DOC filters are, it’s time to familiarize yourself with the distinctions between these two essential parts of a diesel vehicle’s aftertreatment system. In most cases, both DPF and DOC filters play a crucial role in keeping an engine running smoothly while protecting the environment against harmful diesel emissions.  

Luckily, many online shops offer various effective filtration systems products for your diesel vehicle. For example, if you have a diesel-powered Chevy truck, many reliable stores offer OEM Chevy line DFP and DOC filters and other related products.  

The two filtration devices have the following differences and similarities that you should be aware of. 

Differences: 

  • Regeneration  

Typically, the DOC filter can be considered the first line of defense in the engine’s aftertreatment system. It’s a honeycomb ceramic filter designed to start the oxidation of carbon monoxide, hydrocarbons, and other organic particulates.  

That said, a DOC filter differs from a DPF filter since the latter is intended to block all remaining soot that the Diesel Oxidation Catalyst can no longer oxidize. The soot should undergo active or passive regeneration so that it’ll not be stuck in the DPF. 

Essentially, active regeneration refers to a process by which raw fuel is introduced to the exhaust stream to set off the temperature over 600 degrees Celsius and further oxidize the soot buildup. On the other hand, passive regeneration happens when the DPF and the vehicle’s normal temperature break the particulates down between 275 to 360 degrees Celsius.  

  • Core Contents  

Regarding the core content, a DPF filter is made from different materials, such as ceramic, cordierite, and silicon carbide. Meanwhile, a DOC filter contains precious metals, like platinum, making it an expensive part of the vehicle’s aftertreatment system.  

But despite the difference in core contents, both DPF and DOC filters are made from specific materials to facilitate the chemical reactions needed to eliminate the harmful substances from the truck’s emission system.  

Similarities:  

  • Maintenance And Servicing  

Although DPF and DOC filters may differ in some ways, they require regular maintenance and servicing to keep them running properly. Failure to clean and take care of these filtration systems may result in congestion which could affect their functionalities. For example, if there’s an excessive buildup of substances, damage may be caused to the exhaust system and your engine as a whole. 

Because of this, DPF and DOC cleaning is required to protect them from premature deterioration due to contamination, congestion, and lack of maintenance. Although you may opt to do the cleanup yourself, it may be best to let professionals handle the job to ensure a more desirable result.  

  • Cost 

As essential parts of the vehicle’s aftertreatment system, both DPF and DOC filters come with high price tags. This can mean spending hundreds to thousands of dollars to replace your filtration systems when damaged. One of the reasons for the high cost may be the materials used in making the filters. For example, buying a DOC filter can be costly because it contains precious metals like platinum.  

Final Thoughts  

Indeed, your truck engine’s aftertreatment system plays an essential role in diesel emissions. Hence, to make the most out of your engine’s powerful performance without harming the environment, you shouldn’t take your DPF and DOC filters for granted. Keep the information mentioned above in mind to know how to handle these filtration systems for the benefit of your vehicle and the environment.  

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About the author

Jimmy Rustling

Born at an early age, Jimmy Rustling has found solace and comfort knowing that his humble actions have made this multiverse a better place for every man, woman and child ever known to exist. Dr. Jimmy Rustling has won many awards for excellence in writing including fourteen Peabody awards and a handful of Pulitzer Prizes. When Jimmies are not being Rustled the kind Dr. enjoys being an amazing husband to his beautiful, soulmate; Anastasia, a Russian mail order bride of almost 2 months. Dr. Rustling also spends 12-15 hours each day teaching their adopted 8-year-old Syrian refugee daughter how to read and write.