Emissions testing equipment provider Premier Diagnostics outlines its role in helping National Express upgrade its bus fleet
With the world focusing on improving air quality for all of us, many cities in the UK are looking to lead by example. Among the most publicly known schemes so far is the Ultra Low Emission Zone (ULEZ) scheme in London, which was introduced in April 2019.
It is no secret that a large portion of NOx and particulate matter (PM) from internal combustion engines is attributed to diesel fuels. We have seen huge improvements in the emitted pollutants from modern Euro VI diesel engines.
A central pillar of the low emission schemes involves the upgrading or conversion of cities’ public transport infrastructure. Whilst many buses in London have simply been replaced as part of the ongoing renewal of assets, much of the Euro IV and V fleet has not repaid its capital investment and cannot be simply written off the books.
As a result, we have seen huge investment and development in retrofit pollution control systems to bring the Euro IV and V, sometimes even Euro III, up to Euro VI standards, that are required to operate within the ULEZ and clean air zones that are being introduced.
A fleet audit in March 2020 showed that over 3,240 buses in London had already undergone the transformation to Euro VI standard, with the works continuing and moving on to the taxi fleet.
The same transformations are taking place in bus and coach fleets across the country. More cities plan to roll out their own low emissions schemes over the coming years. There are varying classes for these schemes, with some enforcing the regulations for all motor vehicles, and others affecting only public transport including buses, taxis and private hire.
One of the next big transitions is taking place in Birmingham. Here, the pre-Euro VI National Express bus fleet is being fitted with HJS SCRT Treatment Systems and Grayson E Fan cooling systems.
The HJS SCRT system combines a diesel particulate filter with an SCR unit for the reduction of nitrogen oxides. HJS UK tailors each system to a specific vehicle type, to maximise operational performance.
Electronically controlled engine cooling and Charge air inlet temperature management ensures engines are warm enough year-round to elevate exhaust temperatures to dose AdBlue and create an efficient aftertreatment process. The two systems are optimised to work together.
All of the retrofit work for National Express has been carried out by Grayson Thermal, within its seven-bay, purpose-built workshops in the West Midlands. This is supported with parts and technical backup by the HJS UK team, based in Swindon (the UK’s official HJS distributor).
At the time of writing, some 800 buses had undergone the conversion process, with approximately 30 further installations to complete the National Express programme.
As with any retrofit programme of this kind, it is important to know the health of the existing system both before and after the conversion process. Premier Diagnostics has been able to supply its popular DS2 Diesel Smoke Meters to National Express and Grayson Thermal Systems.
This allows them to carry out pre-install checks, such as measuring the raw particulate levels produced by the engine, and if this is within or over a predetermined limit, to then proceed with the upgrade fitment. They can work to identify and rectify electrical and mechanical faults before the retrofit, ensuring the system will not be overwhelmed and become quickly blocked, and preventing unplanned cost and consequential damage.
With the vehicle back in service, the Diesel Smoke Meter can then be utilised, to test raw engine particulate emissions via an inspection bung pre-DPF, and by sampling at the tailpipe to confirm the efficacy of the DPF post-conversion as part of an ongoing maintenance and compliance programme.
Ian Hateley, Grayson Thermal Systems service director, commented: “The DS2 Smoke Meter suited our needs perfectly. It proved simple to use following the operational training. We quickly found the first one was reliable and accurate, in a busy workshop environment. Having used one system and being completely satisfied, we have now invested in two more for the field service vehicles supporting National Express, on behalf of HJS in the West Midlands area.”
National Express project manager Paul Jenkins said: “We have also invested in replacing some of our older less reliable, other types of testing units in garages. Having a fully reliable, available and accurate smoke level tester is essential in a busy bus garage environment. The DS2 units we had have given exceptional reliability, and are able to meet the needs we have for accurate recording of the raw emission smoke level.”