As a facility manager, ensuring the smooth operation and compliance of your commercial generator is a critical part of keeping your property prepared for emergencies. One key part that plays a vital role in maintaining emission standards and protecting the environment is the Diesel Particulate Filter (DPF). There are two main types of DPFs used in commercial generators: active and passive. Understanding the differences between these two can help you make informed decisions about the maintenance and operation of your facility’s generators.
What is a Diesel Particulate Filter?
A Diesel Particulate Filter is a device installed in the exhaust system of diesel engines to reduce the amount of particulate matter (PM) or soot that is released into the atmosphere. These filters trap and hold the soot until it can be burned off or “regenerated,” reducing harmful emissions and helping generators meet stringent environmental regulations.
Active Diesel Particulate Filters
Active DPFs require external energy sources to regenerate, or clean, the filter. Johnny Bradford, Duthie Power Quality Assurance and Safety Manager featured in the video above, explains, “The difference between an active and passive diesel particulate filter is an active diesel particulate filter is a unit that provides its own heat, meaning that it’s hooked up to a 480-volt system.”
This energy can come from a variety of sources, such as diesel fuel injection, electrical heating elements, or exhaust gas burners. The key characteristic of active DPFs is that they initiate the regeneration process regardless of the engine’s operating conditions.
- Pros:
- Reliability: Active regeneration ensures that the filter is cleaned at regular intervals, preventing clogging and maintaining generator performance.
- Flexibility: These systems can regenerate even when the engine is operating at low loads, which is common in many commercial applications.
- Cons:
- Higher Operational Costs: The need for additional fuel or energy sources increases operational expenses.
- Complexity: The system’s added components require more maintenance and can introduce more points of potential failure.
In terms of maintenance, the frequency of filter changes depends on the manufacturer’s recommendations. As Johnny says, “There are some that you have to pull out and replace every 20 starts. There are some that you have to do annually. It just depends on the equipment manufacturer.”
Passive Diesel Particulate Filters
Passive DPFs rely on the engine’s exhaust temperature to trigger the regeneration process. These filters use a catalyst to lower the temperature at which soot is burned off, allowing regeneration to occur naturally during regular operation when the exhaust temperature is high enough.
Johnny adds, “The passive diesel particulate filter is a unit that does not require an external source of heat. Usually, it’ll have a system within the engine itself that provides extra fuel to burn inside. The unit goes through a diesel oxidization catalyst that warms everything up, that heats it up, then it burns inside there, and it gets trapped in the filter.”
- Pros:
- Lower Operational Costs: Since passive systems do not require additional fuel or energy sources, they are more cost-effective to operate.
- Simplicity: Fewer components mean less maintenance and fewer potential failure points.
- Cons:
- Dependency on Operating Conditions: Passive regeneration only occurs when the exhaust temperature is sufficiently high, which may not be the case in all operating conditions. This can lead to soot accumulation and potential filter clogging.
- Less Control: Facility managers have less control over when regeneration occurs, which can be problematic in generators that operate under varying loads.
Which Generator Filter is Right for Your Facility?
The choice between an active and passive DPF depends on the specific operating conditions of your facility’s generators. If your generators often run at low loads or operate in conditions where exhaust temperatures are typically low, an active DPF may be the better choice despite its higher operational costs. On the other hand, if your generators operate under conditions that naturally allow for sufficient exhaust temperatures, a passive DPF could offer a more cost-effective and simpler solution.
Conclusion
Both active and passive DPFs have their advantages and drawbacks. As a facility manager, it’s essential to evaluate your specific generator usage and operating conditions to determine which type of DPF will best meet your needs. By making the right choice, you can ensure your generators operate efficiently, comply with emission standards, and minimize maintenance costs.
