The Ins and Outs of Diesel Particulate Traps

The diesel engine is an internal combustion invented a few decades after the gasoline version. It is more efficient, delivering up to 30 percent better mileage than its gasoline equivalent. Diesel engines are increasingly popular, particularly in Europe where over 50 percent of new automobiles are diesel-powered. However, diesel exhaust contains particulate matter that is almost absent in gasoline engines. Because such particulate matter is carcinogenic, most jurisdictions demand effective particulate traps. Unfortunately, the typical diesel particulate trap is not suited for purely urban driving; regular maintenance is required, and the need for repairs does arise.

What are Particulates?

Particulates are tiny pieces of solid or liquid matter that are small enough to form aerosols when combined with air. For example, the trail of smoke coming off a burning cigarette is visible primarily because of the particulate matter it contains. Typical particulates include soot, tobacco smoke, and cement ash.

How do Particulates Affect Health?

Particulates are very fine particles that can easily reach the innermost portions of your lungs when breathed in. The surface of such particles also makes it easy for them to lodge in the lungs disrupting breathing. Diesel exhaust, which has significant particulate matter if not trapped, can cause coughing, breathing difficulties, and chest tightness. Certain particulate materials are also believed to be carcinogenic.

Which Automobile Engines Need Particulate Traps?

Gasoline and diesel are produced from the same raw material, oil. However, differences in their production processes result in different end-products. While diesel is more energy dense than petrol, it does contain a different set of hydrocarbons that result in much higher particulates when burnt in engines. Consequently, diesel engines require particulate traps while gasoline engines do not.

How do Diesel Particulate Traps Work?

A diesel particulate filter (DPF) removes particulates by the simple process of filtration. Exhaust air is passed through a filter that traps particulates while allowing exhaust gases through. This, of course, means that the DPF slowly clogs over time and needs to be cleaned periodically. Most modern DPFs accomplish cleaning by a process of regeneration. In many vehicles, this happens onboard and automatically. The process involves the injection of excess fuel into the engine, which is used to clean the filter by burning off collected soot.

What are the Types of Automobile Particulate Traps?

The most common automobile particulate traps use a filter made of a ceramic called cordierite. The disadvantage of cordierite is its low melting point, making regeneration more complex. Silicon carbide filters are also popular because of their higher melting point and because they are built to easily replace existing cordierite filters. Metal fiber filters, more expensive than cordierite or silicon carbide filters, have the advantage of being able to use electrical energy to burn off collected particulates.

Particulate traps are required to eliminate fine particles present in exhaust gases. Automobiles powered by diesel engines produce far more particulate matter than gasoline engines; consequently, diesel particulate filters are increasingly being mandated by legislation in many countries. Most modern particulate traps accomplish the removal of particulates collected through an automatic regeneration process. However, if your console indicates a malfunctioning filter, visit your mechanic immediately, as the repair bill is likely to increase dramatically with procrastination.