Engelhard particulate filters for New York City buses

20 February 2002

Iselin, NJ-based Engelhard Corporation announced that 690 urban buses in New York City will be equipped with its DPX particulate filter system. The buses include 190 new and 500 existing vehicles.

Engelhard’s DPX™ technology is a catalyzed diesel particulate filter (DPF) which is intended to passively regenerate under exhaust temperatures during normal operating conditions, without the need for external controls or heating devices. The filter reduces over 90% of particulate matter (PM) emissions. It also significantly reduces hydrocarbons and carbon monoxide emissions. On DDC engines, the filter has been approved by the engine manufacturer and will not affect the warranty coverage. The filters will be used with ultra low sulfur fuel of less than 30 ppm S, which is used by all buses operated by the New York City Metropolitan Transit Authority (MTA).

Installation of diesel filters by the MTA follows the commitment by the New York Governor George Pataki, announced in the Spring 2000, to ensure that the MTA has the cleanest bus fleet in the world. This plan is to be achieved by purchasing of new clean-fuel buses (diesel-electric and natural gas) and retrofitting existing diesel buses with particulate filters.

The MTA has evaluated various particulate filter technologies on its buses and found a certain sensitivity of the passive DPF performance to the engine technology, with a satisfactory filter regeneration on DDC Series 50 engines, but with several instances of filter plugging on the 2-stroke 6V92 engines. Based on these findings, the MTA has decided to retire the 2-stroke engines and to retrofit all 4-stroke engines with DPFs. The entire fleet of approximately 3,500 buses is planned to be retrofitted with various DPF technologies by the end of 2003. This retrofit program, first on such a scale in North America, started in the Fall of 2000.

Source: Engelhard Corporation