ADAPTech Projects

My bag material is some kind of upholstery, I got from a friend that worked in a textile mill. Feels like some kind of poly blend. I’ll take photos of it with light showing behind it.


Jakob, you must have read that I use raw sheep’s wool for the filter medium. At the bottom of the container there is a grid to distribute the gas evenly across the cross-section, here I insert a layer of 20 cm of sheep’s wool, then a layer of 20 cm of sawdust, then a layer of fine hay and, finally, a layer of sheep’s wool on top, which surrounds the oval final filter made of felt. I can say that it works perfectly and the water drains nicely from the wool. The tractor has done 150 hours on wood gas and so far the intake line is completely clean. Let me not forget to say that I change the filter material every 40-50 working hours and what pleases me the most is that all the material is biodegradable and is not harmful waste, just like plastic or synthetics.


I am planning on using a bag for the hay in the hay filter, with another bag of sawdust on top of it. @Matt only uses sawdust in his ammo box filters so I figure it must work pretty well.



Jacob, I use hay in a nitted wollen bag. Not perfect, but good enough for me. I believe it’s more important to prioritize breathing capability if you’re running a motor which you expect to operate within a wide range of power.


What JO said ,

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Here’s my upholstery material, it’s rough on the outside, I leave that on the dirty soot side of filtering.
Here’s the pictures with light showing through it.
I use mosquito screen behind the sack filter to stiffen it so maybe the screen is also catching some finer soot, but I’ve noticed and as Kristijan has advised as the sack gets dirtier the better it filters. I never washed the filter only shook it.
It even worked for my 4.3, the sack was about 18" wide by 36" long when laid flat, hose clamped to a stand pipe.


I am interested in the sheep’s wool. There are many varieties by that name. Can you suggest a specific product available on-line which is similar to what you use and might be reasonably priced.


He probably means raw unwashed wool, which still has lanolin on the hairs. Lanolin is oily so it would grab dust and repel water very easily.


You could try a foam rubber, I use about 3" thick and get very little soot with it, and this has very little resistance, look at filters for lawnmowers, for example.