The California Air Resources Board (ARB) has given its approval to a new diesel emissions control system designed by Extengine Transport Systems.

The regulatory board sanctioned the firm's Extengine Transport Systems Advanced Diesel Emission Control (ADEC) system, verifying the system for model years from 1991 to 1995 on off-road Cummins 5.9-litre diesel engines from 150 to 200 horsepower.

Typically the engines are used in heavy vehicles such as loaders, excavators and dozers, and also tractor rigs.

In addition, the system works with either standard CARB or ultra low sulphur diesel fuel.

Using a diesel oxidation catalyst, selective catalytic reduction catalyst, and ammonia slip catalyst, the ADEC system is able to slash particulate matter emissions by 25 per cent and also delivers an 80 per cent reduction in NOx emissions.

Extengine Transport Systems works in a number of areas, but is chiefly concerned with transportation technology design, licensing and emissions testing, and is aiming to exploit the commercial potential of reduction technology.