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Passive Filtration Systems  (CRT-SMF) for heavy duty applications


Passive filtration systems rely on higher exhaust temperatures to regenerate and keep clean. These are typically suited to machinery running at medium to high load for the majority of the duty cycle. SMF® technology has been developed specifically for applications in the medium to high power range. 


As a rule, the systems replace the original silencer, and they can be customised as required to match specific machines and stationary applications.


The modular SMF® systems require no extra regeneration aids, additives or intervention in the engine management system. The HJS Service Unit constantly displays the system's instantaneous operating state and indicates when the filter is in need of cleaning.




  • No need for time-consuming and costly replacement of mobile machinery and stationary applications

  • Reduction of soot particles and fine particulate matter by more than 99%

  • Flexible adaptation to different machines and engine power outputs

  • Optional catalytic coating provides extended temperature window


Functional description


The hot exhaust-gases from the engine – which contain soot particles – are fed into the housing of the SMF®. The gaseous components flow through the microscopic pores of the filter pockets; the soot particles, including the fine particulate matter, are trapped on the surface and deposited on the individual filter pockets.


HJS's proven SMF® technology with passive regeneration is used to break down the soot that collects in the SMF®. The HJS system combines a highly efficient, upstream diesel oxidation catalyst (DOC) with an SMF®. Optimised tuning of the system results in the filter being continuously and effectively freed from the deposited soot.

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Energy Saving Trust Approved DPF's

HJS CRT-SMF brochure

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