# Building large Gasifier
**URL:** http://forum.driveonwood.com/t/building-large-gasifier/6839
**Category:** General Discussion
**Created:** [August 9, 2022, 7:29am UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839 "2022-08-09T07:29:08Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Red](http://forum.driveonwood.com/u/Red)
#### Post date: [August 9, 2022, 7:29am UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/1 "2022-08-09T07:29:08Z")
Building large Gasifier, 10 in. x 24 in drop tube reactor. Just wondering about access pressure. Vent it? Should I run gauge on it?
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### Author:  [@tcholton717](http://forum.driveonwood.com/u/tcholton717)
#### Post date: [August 9, 2022, 1:52pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/2 "2022-08-09T13:52:49Z")
Welcome to the site Red. I like your last name. Really not enough information to answer your question. Need to know more about your design.
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### Author:  [@r\_wesseling](http://forum.driveonwood.com/u/r_wesseling)
#### Post date: [August 9, 2022, 2:57pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/3 "2022-08-09T14:57:20Z")
Hi Red,
It seems like most raw wood gasifiers are vented using a poof cover, which is usually just a barrel lid held down with springs. But the charcoal gassers usually don’t vent, and get away with it. I would say it’s always safer to vent. Like cheap insurance.
I assume 10" diameter, 24" nozzle to restriction?
Rindert
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### Author:  [@ForbiddenTuna](http://forum.driveonwood.com/u/ForbiddenTuna)
#### Post date: [August 9, 2022, 8:24pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/4 "2022-08-09T20:24:52Z")
Normally speaking the gasifier does not create pressure, the system is under vacuum, and not a whole lot considering it is best measured in Water Column.
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### Author:  [@Red](http://forum.driveonwood.com/u/Red)
#### Post date: [August 9, 2022, 10:07pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/5 "2022-08-09T22:07:47Z")
Howdy, Rindert, I messed up on measurements, drop tube is L22in.x8.5 I.D. Am an ole fart lol As Large as I have built it was`nt sure of excess gas. It design from downdraft Fema/gasifier or close to it.
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### Author:  [@ForbiddenTuna](http://forum.driveonwood.com/u/ForbiddenTuna)
#### Post date: [August 9, 2022, 10:14pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/6 "2022-08-09T22:14:59Z")
The FEMA really isn’t the best design to go off of. It’s possible sometimes to modify it into an Imbert design but it’s usually worth the effort to just build a new one.
Do you have any pictures of it?
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### Author:  [@pobrien603](http://forum.driveonwood.com/u/pobrien603)
#### Post date: [August 9, 2022, 11:36pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/7 "2022-08-09T23:36:03Z")
I guess a good question to get out of the way is what do you intend to power with your gasifier? Will you be burning the gas in an internal combustion engine? What size is it? Or do you intend to burn the gas in a burner for a heating application? The best operating gasifier are sized to the job. FEMA gasifier are only for short term extreme emergency builds. They will cause lots of tar (stuck valves) with an engine. You can look on here in the library concerning more reliable Imbert style gasifiers.
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### Author:  [@TheIrishEngineer](http://forum.driveonwood.com/u/TheIrishEngineer)
#### Post date: [June 19, 2023, 10:06pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/8 "2023-06-19T22:06:04Z")
This will sound silly, but I’m bordering on making a gasifier with a setup to convert wood to charcoal, and then intentionally filtering out the tar on purpose so that I can save it for household repairs later. I’m sure it doesn’t sound very productive, but the idea of being able to save anything from the process makes it feel more efficient to me. Let alone what could be used potentially as an industrial adhesive
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### Author:  [@tcholton717](http://forum.driveonwood.com/u/tcholton717)
#### Post date: [June 19, 2023, 11:02pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/9 "2023-06-19T23:02:24Z")
> [@Charcoal kiln, Kursk 2.0](https://forum.driveonwood.com/t/charcoal-kiln-kursk-2-0/5761/27):
>
> Yesterday we talked a little with Kristjan about the co-production of wood tar and wood vinegar in cooking charcoal, and here I am attaching a sketch. Let me also mention that Kristjan provided me with a premium membership, … thank you.
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### Author:  [@TheIrishEngineer](http://forum.driveonwood.com/u/TheIrishEngineer)
#### Post date: [June 20, 2023, 10:55pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/10 "2023-06-20T22:55:06Z")
Regardless of size of gasifier, is there a good visual indicator as to whether or not you have a good clean output? I tried pulling some stuff up on YouTube, but there are such wide differences between multiple videos that claim that they have clean output that clearly some of them must not be accurate in their reading
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### Author:  [@NonProfit](http://forum.driveonwood.com/u/NonProfit)
#### Post date: [June 20, 2023, 11:02pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/11 "2023-06-20T23:02:26Z")
> [@TheIrishEngineer](#):
>
> is there a good visual indicator as to whether or not you have a good clean output
I’m no expert, but I thought clean gas has a clear blue flame.
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### Author:  [@TheIrishEngineer](http://forum.driveonwood.com/u/TheIrishEngineer)
#### Post date: [June 20, 2023, 11:21pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/12 "2023-06-20T23:21:32Z")
I would assume that as well. But I figure it couldn’t hurt to ask just in case I was wrong. The second I assume that I’m right is always when things start to go wrong, haha. Best to be safe then sorry
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### Author:  [@ForbiddenTuna](http://forum.driveonwood.com/u/ForbiddenTuna)
#### Post date: [June 21, 2023, 12:27am UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/13 "2023-06-21T00:27:23Z")
Wayne always says you shouldn’t see a lot of smoke in the gas when it isn’t lit, but maybe a thin haze. That’s when flaring before the filter.
Good woodgas also readily and quickly ignites with just a spark. A flint striker for a gas torch would be a good example to light a flare with.
You can use cloth filters that will clog when tarred up, or another fine media like carded wool. Hay is more of a coalescer but it’s important to have something like hay before any other filter media.
Gas flare color is somewhat of a red herring especially in different light levels.
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### Author:  [@TheIrishEngineer](http://forum.driveonwood.com/u/TheIrishEngineer)
#### Post date: [June 21, 2023, 1:48am UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/14 "2023-06-21T01:48:20Z")
im planning on making a multi stage filter. ive taken a look around the forums and havnt seen any designs like the one i had in mind yet, so im hopeful
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### Author:  [@pobrien603](http://forum.driveonwood.com/u/pobrien603)
#### Post date: [June 21, 2023, 2:03am UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/15 "2023-06-21T02:03:37Z")
Thomas, You will find when you have more reading, videos, in-person viewing, discussions with seasoned woodgas guys that some of the youtube videos proclaiming that they make good clean gas are mostly a spoof for youtube ratings. One engine run and you never see another post about woodgas. The worst part is people see those videos and build something like them and tar up an engine and then swear that woodgas doesn’t work.
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### Author:  [@TheIrishEngineer](http://forum.driveonwood.com/u/TheIrishEngineer)
#### Post date: [June 21, 2023, 2:07am UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/16 "2023-06-21T02:07:21Z")
thats the feeling that i got. SO MANY videos on wood gas and people claiming they are doing it “right” and then dont know why their motor is seizing up.
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### Author:  [@TheIrishEngineer](http://forum.driveonwood.com/u/TheIrishEngineer)
#### Post date: [June 21, 2023, 2:08am UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/17 "2023-06-21T02:08:42Z")
before i EVER touch a pipe to my motor, im going to do everything in my power to make the gas clean. gotta make sure i work on a strong foundation. cant build a house on a foundation of sand
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### Author:  [@KristijanL](http://forum.driveonwood.com/u/KristijanL)
#### Post date: [June 21, 2023, 5:21am UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/18 "2023-06-21T05:21:46Z")
Thomas, if l understand right you plan to make a charcoal kiln and run an engine on the exess gas? In that case l wuld first run the gas trugh a water cooled cyclone. It shuld collect most tar. Then a good electrofilter. If you want to collect tar other filtration sistems may not work.
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### Author:  [@TheIrishEngineer](http://forum.driveonwood.com/u/TheIrishEngineer)
#### Post date: [June 21, 2023, 6:19am UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/19 "2023-06-21T06:19:20Z")
Not necessarily. My dream world idealistic setup would be a gasifier capable of using wood pellets that I can produce myself from limb scraps.
What I was talking about with the charcoal kiln is just how much it feels like a shame that all those gases and tars are going to waste, and how it would be kind of nice to save the tars if possible. If I could make a charcoal kill that would be able to filter enough to the point of making the gas is usable that would be fantastic! I had not even considered that
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### Author:  [@Bobmac](http://forum.driveonwood.com/u/Bobmac)
#### Post date: [June 21, 2023, 3:42pm UTC](http://forum.driveonwood.com/t/building-large-gasifier/6839/20 "2023-06-21T15:42:55Z")
> [@ForbiddenTuna](#):
>
> You can use cloth filters that will clog when tarred up, or another fine media like carded wool. Hay is more of a coalescer but it’s important to have something like hay before any other filter media.
Tar is carried in a gases state when made. It will pass through filter medium before clogging it up. Rule number one you can not really filter out tar, it is best to not to let it go throught the hot charbed in the first place. Having a good Charcoal bed from the nozzles on down to the grate that is established is the goal before lighting the gasifier up. Always preload the gasifier before your first light up.
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