Ensuring Stage V emissions compliance through scheduled DPF cleaning

Since it started in 2019, the phased introduction of the EU Stage V emissions standard for Non-road Mobile Machinery (NRRM), has seen a considerable amount of development in the engines powering off-highway equipment, in order to meet stringent limitations on harmful substances in exhaust gases.  These include Nitrogen Oxides (NOx), Carbon Monoxide (CO), Hydrocarbons (HC) and particulate matter.

Applicable to all mobile industrial equipment powered by compression-ignited or spark-ignited engines, the scope of the Stage V standard is considerable, covering machinery commonly used in industries, including agriculture and construction, as well as more niche sectors such as aviation ground support equipment.

To prevent noxious particulate matter, including soot and ash, from entering the atmosphere, Stage V compliant engines with an output of 36kW or greater are fitted with a diesel particulate filter (DPF) as part of the powertrain’s exhaust after treatment system (EATS).  Soot deposits are largely removed automatically by a continuous, ‘passive’ regeneration process, which occurs during normal operation.  The high temperature in the DPF causes soot particles to oxidise, converting them into CO₂ and water vapour.

Where a diesel engine has a less demanding duty cycle, however, passive regeneration is likely to be insufficient due to faster accumulation of soot deposits in the DPF.  Instead, ‘active’ regeneration is initiated.  This process involves raising the temperature of the exhaust gases to facilitate the burning of soot particles and is achieved through less efficient, energy-consuming measures such as increasing engine load, injecting fuel into the exhaust system, or using electric heaters.

Besides soot, non-combustible ash also builds up in the DPF over time which needs to be removed from the filter off-vehicle at regular intervals, depending on the specific duty cycle of the engine.  Ceramex, the UK’s leading scalable provider of DPF cleaning and remanufacturing for HGV and off-highway vehicles, offers specialist cleaning processes to remove soot and ash deposits, which restores the filter’s performance to ensure Stage V emissions compliance.  These include the company’s patented Flexpurge^® system for ‘closed-end’ or sealed units, which are typically installed in Stage V off-road equipment and the Xpurge^® system for standard DPFs, normally found in on-road applications such as HGVs.

A saturated DPF quickly loses its effectiveness and immediately causes a reduction in engine performance.  Detailed research by Ceramex has found that a unit in this condition is likely to result in a minimum 2% increase in fuel consumption, compared to a clean filter.

When the volume of soot and ash inside a DPF increases, the back pressure rises, which produces a higher load on the engine, required to force the exhaust gas through the DPF.  Consequently, this consumes more fuel and can also cause excessive stress to the engine and emissions system, which in turn increases the risk of breakdown, subsequent downtime and the need for expensive component replacement.  Should 20% of a filter become blocked, for example, the remaining 80% of its capacity works harder to remove noxious contaminants, thereby putting greater pressure on the unit and heightening the chances of failure.

Processing typically more than 2,000 DPF cleans per week from its 67,000 square-foot facility in Reading, Ceramex operates a number of tailored service packages, where batches of saturated DPFs are collected from customers, both in the UK and in Europe.  Using a fast turnaround, contract-based approach, minimises downtime for operators and delivers cost efficiencies through economies of scale and a planned approach to DPF cleaning.  From an environmental perspective, the process ensures a vehicle or machine operates efficiently, in accordance to its duty cycle.

Ceramex’s Xpurge^® cleaning process, which uses an innovative combination of de-ionised water and compressed air, removes accumulated soot and ash deposits within the DPF.  Xpurge^® collects the particulate matter in aqueous suspension, which eliminates any risk of noxious particulates entering the atmosphere.  This process is unique to Ceramex globally.  After cleaning, Ceramex’s patented Veritex^® technology provides a detailed internal inspection of the DPF and quality assurance relating to the filter’s condition when returned to service.

Taking an environmentally responsible approach to waste disposal, Ceramex is the only HGV DPF cleaning provider that operates an onsite treatment plant.  This facility removes all the particulate matter from the water used for cleaning through a continuously monitored filtration system.  The water is then returned to the grid in a cleaner state than its source and the solid matter is safely disposed of by a government licensed third party, in accordance with environmental regulations.