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Diesel particulate filters (DPFs)

Diesel emissions contain carcinogenic particulate matter that not only negatively affects respiratory and cardiovascular health, but also contributes to climate change. At Rypos, we have over 25 years of experience developing cutting-edge diesel particulate filter (DPF) systems that eliminate up to 95% of particulate emissions. If your application uses mobile or stationary diesel engines, our active DPFs can help you improve your sustainability efforts and achieve compliance with air quality regulations.

DPF technology explained

What is a DPF?

Diesel particulate filters (DPFs) are exhaust-treatment devices that can be fitted to a wide variety of engines. DPFs trap harmful pollutants and prevent them from reaching the atmosphere, where they can cause significant environmental damage and impact to human health.

RH-DPF diesel particulate filter

Active vs. passive regeneration DPFs

Active DPFs

Unlike passive DPFs, active DPFs are self-cleaning. This cleaning, also known as regeneration, is automatic regardless of exhaust temperatures.

Other filter manufacturers claim to have active regeneration, the Rypos’ active DPF maximizes the safety, reliability and uptime of your engines and generators. Competitor systems require additional loads on the gen set and extended run times resulting in increased fuel costs for filter cleaning.

The Rypos’ active DPFs efficiently burn soot accumulated in the filter at 700 oC in under 3 minutes while using less than 1% of the generator output. Heaters or load banks are not required to elevate exhaust temperatures for filter cleaning. Facility owner and operators can be confident in the availability of their emergency systems.

Passive DPFs

Passive filters have cleaning limitations. These filters are only able to regenerate under conditions where the generator is allowed to run long enough to elevate the exhaust temperatures.

When specific exhaust temperatures are not met the filter will eventually plug up with soot and engine back pressure will increase beyond acceptable limits, leading the engine to shut down and eventually fail. Facility operators must follow passive filter service guidelines, particularly related to counting cold starts, for proper operation.

Why Rypos?

What makes Rypos active DPFs better?

25 years

At Rypos, we’ve been focusing 100% of our efforts on advancing active diesel particulate filter technology for over two decades.


Our proven active DPF technology has been working for over 25 years in mission-critical applications that require extreme dependability.


Working instantly on installation, our active DPFs immediately eliminate up to 95% of the black carbon soot emitted by diesel engines.


Our active DPFs meet CARB Level 3+ and EPA Tier IV final standards, reducing emissions and keeping older diesel engines in service longer.

Rypos products

Diesel particulate filters

All Rypos products are active, self-cleaning DPFs that require minimal maintenance. These energy-efficient units reduce DPM emissions up to 95% and are CARB Level 3+ Verified (Marine Pending Level 3+).


Designed for 1 MW and above diesel gensets, ADPFs provide critical or hospital-grade sound attenuation for applications such as data centers, healthcare, and universities.

View ADPFs


Built for standby and prime generator sets, marine engines and generators and gantry cranes, in the 50 to 900 kW range. RH series DPFs provide critical- or hospital-grade sound attenuation.



In-stock and ready to ship, Rypos’ Ultra-Low Emission Transport Refrigeration Units (ULETRU) DPFs don’t require any driver intervention and are compatible with either Thermo King® or Carrier® TRUs.


Custom DPFs

We also build custom DPFs with flexible design configurations for other applications based on your specific needs, the diesel engines in operation, and the demand placed on your engines.

See custom DPFs

More about DPFs

Frequently asked questions

If you’re involved in transport refrigeration, power generation, port equipment, marine power generation & propulsion, or OEM & custom solutions, the following answers may give you a better understanding of Rypos’ active DPFs.

Diesel Particulate Matter is a byproduct created when diesel engines combust fuel. It has harmful effects on respiratory and cardiovascular health and is second only to CO2 in increasing global warming.

DPF stands for Diesel Particulate Filter. These filters remove harmful diesel particulate matter emitted from diesel engines, protecting the local environment and the health of area residents.

The EPA first mandated that all three-quarter-ton+ trucks install diesel particulate filters in 2008. Since then, regulations have become increasingly stringent.

Active regeneration is a process in which filter cleaning is not dependent on exhaust temperatures, engine loads, the number of cold starts, or the engine run time. Due to their independence from other factors, active regeneration systems are significantly more reliable than passive regeneration systems.

Passive regeneration is a term applied to filters that have a limited ability to self-clean or self-regenerate. Regeneration can only occur passively when specific conditions of elevated exhaust temperature are accompanied by precise NOx:PM ratios. Given the variation in load, ambient temperatures, distance from the engine, number of cold starts, and engine run time, it is impossible to guarantee filter reliability or emergency power availability with a passive system.

Active DPFs are diesel particulate filters capable of self-cleaning, also known as regenerating. These DPFs perform automatic regeneration regardless of exhaust temperatures, engine loads, the number of cold starts and engine run time.

Passive regeneration is a term used to describe filters that have a limited ability to self-clean or self-regenerate. These filters are only able to regenerate under narrow conditions with specific NOx /PM ratios when exhaust reaches elevated temperatures.

Passive systems also require routine maintenance and supervision of idle operation time, cold starts, and back pressure.

Rypos’ active DPFs are extremely efficient and reliable, requiring very little maintenance. Passive DPFs are significantly less efficient and reliable than active DPFs, requiring routine maintenance and supervision.

Yes. Our active DPF systems can be configured with selective catalytic reduction (SCR) to achieve NOx reductions of 95% or more, meeting Tier 4 standards.

Genset and RTG filters are powered when the generator is running. Rypos-supplied transformers are fed by a breaker off of the emergency distribution panel.

TRU filters are powered by a 105- or 120-amp alternator when the engine is running.

Rypos DPFs will not negatively affect engine performance. Our DPFs maintain an average back pressure well below engine manufacturers’ specification.

Rypos filters only require a very low level of maintenance. We suggest visually inspecting DPFs every 1000 hours.

Rypos filters provide sound attenuation, eliminating the need for a separate silencer for standby applications. Our filters can be mounted inside or outside of the enclosure, and we work with our vendors to ensure that the installation meets sound specifications.

Contact a Rypos emissions reduction specialist at info@rypos.com or call 508-429-4552.

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Have questions about our active DPFs or ready to get started? Contact our emissions control specialists today.