• Generator Services

Does My Generator Need a DPF (Diesel Particulate Filter)?

DPF (Diesel Particulate Filter) or sometimes called PM (Particular Matter) filters are used in diesel engines to capture particulate matter emissions. Think of that black diesel soot you see when a diesel tractor accelerates. This soot is a hazardous material that is harmful to health (1). EPA and CARB (California Air Resources Board) continue to require the use PM filters in generators to meet emissions requirements – especially in sensitive receptor areas (near schools, neighborhoods, hotels, hospitals). Your air district and CARB determine whether or not you need a DPF.


These aftertreatment devices utilize a combination of filtration layers to prevent harmful diesel emissions from being released into the atmosphere. Filters can remove 85%-98% of diesel soot, benefiting the environment and air quality. These filters are self-regenerative – collecting the PM and cleansing themselves by burning off the particulates with a process called regeneration. This incineration of the particulate matter reduces emissions.


There are two primary types of DPFs: active regeneration and passive generation. Active regenerative filters inject additional fuel or electric current into the DPF to reach temperatures needed burn off soot as part of their normal operations. Passive regenerative filters burn off soot when the engine exhaust routinely reaches temperatures between 450 -700 degrees F, however these temperatures are hard to reach when the generator is not under load. Low exhaust temperatures can cause passive DPF’s to clog with particulate matter.


So how do you know what type of DPF your generator requires? It really depends on how you use your generator. If it’s only used for back-up power and run only a few hours a year and under low loads, you may need to install an active regeneration system as you’re not going to get to the temperatures required for a passive system to work effectively. Alternatively, you would need to plan to have annual maintenance for your passive DPF by bringing in a load bank equipment to create an environment where the passive filter will regenerate. If your generator runs routinely under heavy loads, then your passive system is likely sufficient.


Our team here at Generator Services can help you determine the best strategy for your diesel Particular Filter Application. We also can install and provide ongoing maintenance for your generator and DPF.


Generator Services Installing a Rypos Diesel Particulate Filter onto a 1MW Kohler Generator for a City Municipality.