Diesel Particulate Filters were added to vehicle emissions legislation in 2009. Sometimes known as DPF the filter removes as much as eighty-five percent of particulate matter or soot from the exhaust gas of a diesel vehicle.
How Does a Diesel Particulate Work?
With a similar appearance to an exhaust silencer, particulate filters operate by forcing engine gasses through a complex honeycomb structure. The channels of the filter are blocked at alternate ends. The gases are forced to flow through the cell walls in order to exit the filter, and the porous cell walls allow gasses to exit, whilst trapping the particulate matter. Diesel particulate systems must be emptied regularly to ensure maximum performance.
Passive regeneration is an automatic process that takes place on long-haul road trips, typically when the temperature of the exhaust has reached a high temperature. One of the primary problems is that many vehicles don’t reach the temperature needed on a consistent basis. This is the reason that manufacturers have developed a process known as ‘Active Regeneration.’
Active Regeneration completed when the soot level within the filter builds to around 45%. When this occurs the ECU will make small adjustments to the fuel injection timing and increases the temperature of the exhaust gas. This in turn increases the exhaust temperature an initiates the regeneration process, burning away the soot trapped in the DPF.
Different Types of Filter
The first type of filter is known as the Cordierite Filter. Providing excellent filtration efficiency and being reasonably inexpensive, the Cordierite Filter has proven to be highly popular. As the name suggests they are manufactured from a ceramic material, called cordierite. The only drawback of these filters is that they have a relatively low melting point which has been known to melt during filter regeneration.
Silicone Carbide Wall Flow Filters
These are considered to be the second most common filter. They have a far higher melting point than cordierite. They are, however, they are not normally as stable.
Ceramic Fibre Filters
These filters are manufactured by mixing various types of ceramic fibres to create a porous media. This can then be formed into any shape to suit various applications. The main advantage of ceramic fibre filters is that they must have a lower back pressure.
Metal Fibre Flow Through Filters
These are manufactured by weaving metal fibres into a monolith. They have the ability to pass electrical current which can heat the monolith for regeneration purposes, however this filter is typically more expensive.
These are the different types of filter that are available to consumers. It’s important to consider the practical applications before deciding on the right filter for you.