WITH environmental pollution being a significant and growing concern, governments and motor manufacturers are working towards reducing harmful emissions from combustion-powered cars.
From 2008 all vehicles sold in South Africa had to meet Euro 2 vehicle emission standards. Euro 3 and 4 emission standards are not yet in force in South Africa, but in Europe the Euro 6 standard has been in effect for some time.
Almost all countries outside of Europe follow the European regulatory standards for vehicle emission control and the laws for clean, low-sulfur fuels.
The 2 in Euro 2 represents the level of the strictness of testing and legislation that was applied to a vehicle. Whenever the emissions standard is reviewed and changed, the number increases, starting with Euro 1 in 1993, up to the current Euro 6. It’s expected the next Euro 7 emissions standard will come into effect around 2025.
Pollutants the emission standards aim to reduce include nitrogen oxide, carbon monoxide, hydrocarbons, and particulate matter or what amounts to soot from diesel combustion systems.
Isuzu Motors South Africa has introduced Euro 5 technology into its New Generation (NG) N and F series range of trucks.
Emission standards for trucks and buses
The emission standards for trucks and buses are defined by engine energy output in g/kWh; this is unlike the emission standards for passenger cars and light commercial vehicles, which are defined by vehicle driving distance in g/km – a comparison to passenger cars is therefore not possible, as the kWh/km factor depends on the specific vehicle.
Ultra-low sulphur diesel
The success of Euro standards is linked to the quality of diesel fuel, particularly the sulphur content ratio. Sulphur oxides are destroyers of filtration equipment.
While 50ppm sulphur (parts per million) is now generally available, government regulations will limit sulphur in diesel to 10ppm – see the sidebar that details the regulation references.
Isuzu truck’s introduction of Euro 5 standards is timeous and matches the change in fuel standards.
Changes in truck engine technology
It all starts with common rail, electronically managed diesel engine. Isuzu Euro 5 engines on initial select models now come with Variable Geometry Turbocharging together with increased injection pressure (up to 2000bar). This means a design that achieves a more rapid boost to increase torque and avoids turbocharger lag. Exhaust Gas Recirculation (EGR) has also been improved on Isuzu Euro 5 engines with a laminate EGR cooler that allows for more effective control of NOx.
The move to Euro 5 comes with after-treatment in the exhaust system. A combined unit comprising a Diesel Oxidation Catalyst (DOC) and a Particulate Oxidation Catalyst (POC) for the N-Series and DOC for the F-Series ensures that emission is limited to Carbon Dioxide (CO2) and Water (H2O).
The unique advantages of the Isuzu system is that there is no need for any additives such as urea to make the technology work for a clean exhaust.
While Isuzu Euro 5 technology can operate with 50ppm diesel, 10ppm diesel will ensure effectiveness.
