EU legislation & London LEZ Requirements
New machines should now comply with at least Stage IV requirements. These have lower NOx limits that require SCR on larger machines. Some machines will have both SCR and particulate filters.
Stage IIIa limits, that came in between 2006 and 2008, generally did not require any exhaust aftertreatment. Stage IIIb limits, that came into effect between 2011 and 2013, had a large reduction in particulate levels and a smaller reduction in NOx limits. Some of these machines use filters to meet these limits, some SCR only, while some did not use either filters or SCR but used mostly engine measures to meet the limits.
The smaller engines generally have more relaxed emissions limits and have avoided the use of any exhaust after treatment. The graph below shows that, even for Stage V requirements, machines below 19 kW have much higher PM limits than the larger machines that will require filters due to both strict limits on both particulate weight and number. The smaller machines from 2019 will have particulate limits 27 times higher than those for the larger machines and will continue to have relatively high particulate emissions. Because of this, and the fact that small machines are more likely to be used in confined spaces leading to dangerously high concentrations of particulate, we have developed The Particulator as a solution to this problem.
The London LEZ
Currently machines working on major developments within greater London need to meet EU Stage IIIA levels, while those working on those sites in the Central Activity Zone or Canary Wharf have to meet Stage IIIB limits. These limits only apply to machines between 37 and 560 kW although it is good practice to apply the limits to all sites and machines.
From 2020 these requirements will tighten to Stage IIIB for Greater London and Stage IV for the Central Activity Zone and Canary Wharf.
The Mayor’s guidance on meeting these requirements is to either reorganise the fleet to use a machine that meets the required standard, obtain new equipment that meets the standards, fit a different engine that meets the standards to an existing machine or retrofit an approved exhaust after treatment device registered on the EST scheme.
As Stage IIIB legislation is tighter for both NOx and PM, retrofit for both these pollutants should be considered but, if it is not possible to retrofit for both pollutants, then just particulate retrofit is acceptable. Generally, SCR is needed to significantly reduce NOx emissions and retrofit SCR is difficult to implement for individual machines. It is also expensive and difficult to package due to its large size.
The Johnson Matthey range of DPFs are approved for London nrmm LEZ and are registered on the EST scheme.