Vert particle filter test procedure and quality standard for new and in-use diesel engines

A new approach is needed to test particle filters for retrofitting Diesel engines. Considering the toxicity of the particles as also the physical and chemical attributes of particle filters, the optimal scheme is to test the components themselves independent of the deployment. That scheme ensures the highest effectiveness with least effort. It also enables evaluation of worst-case situations and assesses the hazards of secondary emissions. The Swiss standard SNR 277 205, which mandates the VERT test procedure, is a first step in that direction. The solution is derived from the physics of the filter media. The filtration of fine particles essentially depends on the particle size and the space velocity. The attributes of the emitting engine are only insignificantly relevant. Hence the physics and chemistry of particle filters can be investigated independent of the engine and its deployment duty. This concept facilitates a very thorough investigation of the size-dependent filtration, aging susceptibility, secondary emissions and extreme situations. Filter systems, which pass this detailed test, perform equally well in every retrofit configuration. This filter test concept was implemented 1998 in the VERT project and is successful for assessing retrofltting [4]. VERT approved fllter systems are already deployed in the Low Emission Zones of Europe, North and South America.