SAF - Silo add-on filter

The Hellmich SAF filter plant is a completely automatic, continuously working dedusting facility.

The robust sheet steel silo add-on filter housing is of welded construction. The filter chambers with mountings for the filter hoses, including the hose bed and nozzle hoses are integrated in this housing.

The functional principle

The fan with three-phase motor is mounted on top of the filter housing. The unit contains several filter hoses which are made of different materials depending on the dust composition, and each connected to form one group. The groups are cleaned off successively at intervals. Cleaning off takes place using compressed air via a solenoid valve and nozzle pipe, and it is activated depending on time.

The compressed air wave causes a rapid, brief overpressure in the filter hoses so that the dust cakes are knocked off and fall down. There is a nozzle pipe above each hose group (row) which is connected to a common compressed air reservoir outside the housing. The solenoid valves can be provided with valve heating for frost protection. The actual cleaning-off
procedure is triggered by a filter controller. Activation of the cleaning valves takes place using an electronics card where the duration of the compressed air waves (impulse time) and the pause duration between compressed air waves (pause duration) can be set.

The cleaning-off impulse should be 0.2 seconds and the pause duration should be 12 seconds, but both values can be individually adjusted. The cleaning process takes place continuously and starts immediately the fan is switched on via a switch or external contact, e.g. from the silo, pressure container or silo vehicle. The suction fan runs in external star delta operation. The unit can also be switched off via a switch or externally.


  • Versatile use
  • Low maintenance
  • Economic, energy-saving operation
  • Compact construction
  • Heavy-duty sheet steel enclosure
  • Practical airflow quantity graduation
  • Can also be used for individual dust qualities

For further information, please contact our service team.