Cyclone Dust Filters

Cyclone Wood Gas Filter:

The cyclone is probably one of the hardest things for people to fabricate decently in a wood gas system.  For me it is no problem at all because I have rotary CNC plasma and 3D CAD to lay out the cuts.  That is why this is one of the first things I want to offer.



(Click to enlarge)

These cyclone filters are all steel construction made right here in Maine.  Their filter efficiency is generally in the 92-95% range depending on the gas speed and particle size.  I have actually tested them and have the data.

Here is a good sizing chart I created to help you choose which model is the most appropriate:


(Click on the image to enlarge)

I offer three sizes:

  • 1 inch pipe inlets/outlet with a four inch swirl body. ($50 inlet and swirl tube only, $100 complete unwelded kit, $200 professionally welded)
  • 1.5 inch pipe inlets/outlet with a five inch swirl body. ($75 inlet and swirl tube only, $125 unwelded kit, $225 professionally welded)
  • 2 inch pipe inlets/outlet with a six inch swirl body. ($100 inlet and swirl tube only, $150 complete unwelded kit, $250 professionally welded)

If you would like a custom size I will consider it but be advised it will be expensive because I generally have to make more than one to prove my CNC code.  This takes significant amounts of time and materials.

These cyclones offer the advantage that they can be cleaned by placing them in a LOW fire so that the tars burn off.  That is how I clean mine.  I place it in my woodstove for a few minutes on a charcoal bed then remove the piece, cool it, wire brush the dusty residue, paint the parts, and reassemble them.  There is no good solvent for wood gas tars.

These cyclones should NOT be considered as a way to remove tar from a gas flow without a cooler assembly.  They are primarily for dust particles and droplets.

Gas Cooler Option:


This is the gas cooler option shown on a 4″ cyclone. It uses a 25W fan to cool the gases.   Please note, this is a test cyclone not a production unit.  I would be horrified if that welding were sold.  It is capable of lowering a 17cfm flow from 250F to 150F or a 12cfm flow from 750F to 350F.  This assumes the unit is clean.  A layer of tar can degrade its heat transfer capacity badly.

Available for $150 extra.

Six Inch Cyclone with Cooler:

If you would like something for large engines such as V-6’s or V-8’s, NSR now offers the two inch inlet/outlet model with a 400cfm cooler package:




These also have a spin on ash bin for easy clean out.  The cyclone is the standard model which operates best at a load of 50hp.  50hp is typical of an American pick up truck/ute under light acceleration.

These are available for $450 plus shipping.

Units Available:

4″ Plain: 1 unit

6″ Plain: 1 unit

4″ Cooled: 0 units

6″ Cooled: 0 units

2 thoughts on “Cyclone Dust Filters”

  1. alain houde said:

    HI Stephen,
    I am trying to built one cyclone but find it too difficult.
    I am happy to did find someone ready to sale one.
    It is not looking like i was expecting for a cyclone.Like in the book “handbook of biomass downdraft gasifier engine systems page 76.
    Because yours have no cyclone in it .
    May you explain to me why it is builded like that?


    • Hi Alain. I am sorry you are having difficulty. My cyclones are simple cylinders because the cone at the bottom offers only a very small increase in effectiveness. The cone simply isn’t worth the effort especially when you consider that you are rarely ever operating the cyclone at its most effective gas velocity.

      Instead of a cone I use an isolation chamber at the bottom of the cyclone. It captures the dust when it transitions from the outer vortex to the inner one.

      I have small engine cyclones available and ready to ship if you would like to order one. Just send me an email at the address under the “Contact Us”.


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