Converting a floor mounted “bag” extraction system to silo mounted filter

The above shows a typical floor mounted bag extraction system where the customer spends more time emptying bags than machining. (normally, this happens when a new CNC router is installed)

Depending on the physical size of the filter it is mounted on a Ranheat 3m or 4m diameter silo of between 14 and 50m3 storage capacity. In the shed on the right was an existing small warm air heater trying to use bags of dust, it was too slow and too labour intensive. The workforce hated changing the bags and hated tipping them into a hopper by hand. It was also a huge Health & Safety issue with masks and overalls needed. A very unpleasant job!!

Ranheat don’t make or install dust extraction systems but used a local dust extraction contractor to modify the ducting.

This is the same filter with the bag plenum removed and bolted directly onto a flanged upstand on the silo roof. The silo is fitted with accredited silo burst panels on the “dirty side of the filter”

Mounted under the conical silo out-feeder there are two Rotary valves. There is also a small cartridge filter on the Transfer screw (inclined) the second rotary valve is between the transfer screw and the feed stoker. This long feed screw and twin rotary valves, ensures no air is transferred from the extraction system to the heater ( 150, 240, 300, 450 or 600 kW) Note heavy duty bends on duct as customer had installed a hogger to deal with off-cuts No more hand loading on this site!


  • 11 August 2022
  • Alexander Franklin