Exhaust systems: keeping it green

At the end of 2023, all new non-road mobile machinery (NRMM) within Europe needs to comply with the New Euro Stage V emission regulations.

These rules, which apply to both diesel and LPG forklift trucks, have been described as the world's toughest emission standards and are designed to improve air quality to protect public health and the environment. The Stage V regulation tightens the restrictions on emissions of particulate matter (PM), particularly nitrous oxides (NOx) and carbon monoxide (CO).

To be concrete, all newly manufactured machines since 2021 need to meet the Stage V standards. This includes machines between 56 and 130 kW as well as machines under 37 kW. These machines are required to produce a maximum of 0.015 g/kW of soot, regardless of engine size. This entails a 40% decrease in comparison with Stage IV, where the emission maximum was 0.025 g/kW.

Manufacturers will need to show engines are compliant with Stage V by putting an emission mark on each engine that can be viewed through the engine access cover. This mark should include the name, manufacturer trademark, engine family name, date of production and a serial number. Engines without this mark will not be compliant.

For LPG trucks, emissions of particulate matter are not an issue, but a catalytic converter is required to eliminate nitrous oxides. The biggest impact is on the diesel forklift market, where the main solution to meeting these requirements has been a diesel particulate filter.

Diesel particulate filters are used to prevent the discharge of soot when an automotive engine is adapted to emit less nitrous oxide. This adaptation includes lowering the combustion temperature using cooled exhaust gas but means that a diesel particulate filter is needed to deal with the resulting soot discharge. 

Forklifts with diesel particulate filters usually need to be cleaned regularly, typically once or twice a week. This involves revving the engine for 20 to 30 minutes to burn the soot. The disadvantage of this, for many vehicles, includes high fuel use, increased downtime and lower productivity.

At TVH, we combine in-house technical expertise with a very wide range of exhaust parts. This range also includes specific parts to monitor or regulate exhaust emissions:

Soot filter/Diesel particulate filter

A diesel particulate filter (DPF) is a vital part in reducing diesel engine emissions. The DPF is designed to reduce diesel particulate matter that is produced during the combustion process. This filter captures soot particles and ash by physically blocking and collecting them on its filter walls. 

Over time, the filter loses its effectiveness due to the accumulation of particles, particularly ash particles. The service life of the filter can be somewhat increased through the regeneration process, where the collected soot is periodically burned off. However, ash particles cannot be burned off.

A diesel particulate filter is highly effective: up to 99% of soot particles are captured and removed from the exhaust.

Catalytic converter

Used within the exhaust system, the catalytic converter reduces harmful pollutants in the exhaust gases like carbon monoxide (CO), nitrogen oxides (NOx) and hydrocarbons (HC), by stimulating several chemical reactions. When these pollutants enter the catalytic converter, they come into contact with a honeycomb-like structure made of ceramic or metal, coated with catalyst materials like platinum, palladium or rhodium. The contact of pollutants with these precious metals result in different chemical reactions:

• Oxidation: CO and HC react with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O), reducing the levels of harmful gases.
• Reduction: NOx is reduced by reacting with CO and HC. This reduction reaction produces N2, CO2 and H2O, reducing the levels of nitrogen oxides.

These chemical reactions convert harmful gases into substances that are inert, or at the least less harmful. The converted exhaust gases now exit the catalytic converter to be released into the atmosphere.

Lambda sensor

Located near the exhaust manifold or in the exhaust pipe (both upstream and downstream of the catalytic converter), is the lambda sensor, also known as an oxygen sensor or O2 sensor. These sensors monitor the oxygen level in the exhaust gases, by generating a voltage signal. When the voltage output is low, this means the air-fuel mixture contains too much oxygen. When the voltage output is high, it indicates a so-called rich air-fuel mixture with insufficient oxygen.

The voltage output is sent to the machine’s engine control unit (ECU), which continuously adjusts the air-fuel mixture into the engine, maintaining an optimal ratio of air and fuel, optimising combustion.

At TVH, you can find parts and accessories for your entire exhaust system. Beyond the soot filter or DPF, the catalytic converter or the lambda sensor, our range includes:

• Exhaust mufflers
• Exhaust seals
• Exhaust purifiers
• Exhaust pipes
• Exhaust protection
• … 

> Explore our entire range