Gasifier Instrumentation

Hello All
I have some new toys to show you. These are custom made thermocouples that I have been using on my woodburners. Type K max temp 2100F made from Inconel with compression coupling for air tight seal. I use two of these on my F-150 now and I am getting ready to install a third one. In the pics. there are two 17" probes two 10" and one 3" I also have access to a full line of digital display readers to go with the probes. I personally am very good at breaking all things and I haven’t broken one of these probes yet (believe me I tried) good solid unit. Regards Sean

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Wow! Very cool. This could add some much needed remote instrumentation. What’s the cost on these and where do we get them?

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Hi Chris,
I have a local company here that makes them. They are top quality at a reasonable price all the probes in the pics. are type K and go for $94.77 a piece doesn’t matter how long you need the price is about the same. I can get you anything you can dream up. One day I plan to send a probe straight down the hopper to the grate and measure the temps this will not be cheap but I will be wealthy in knowledge. Since these are not sitting on a shelf and made to order please allow up to 2 months to be complete. Good things always take awhile. These probes have been a huge help in understanding gasification and have saved me a lot of heartache. Regards Sean

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Any chance you have a PDF Spec sheet for those? They look like they would integrate well with my PLC control system, I would like to see any info you have on them!

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Hi Henry,
Very cool a PLC would be great!! Unfortunately
I do not have a spec sheet on them at this time :frowning: I will call the company and get one from them to post here.
Is there anything specific you would like to know ? I can make sure it’s on the sheet. Regards Sean

Strike That

I just talked to them they don’t have spec sheets because all there work is custom made.
What kind or brand of plc are you running? I can tell you these probes are type K with a millivolt A/C Signal
And your PLC Seimens, Allen Bradley ect. should have a card that adapts to read these probes.
I hope this helps let me know Regards Sean

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GE Fanuc PLC’s, I dislike Siemens anything (overpriced and unreliable) and Allen Bradly rapes you on hardware and then twice more for the programming software - GE PLC’s are available on eBay all day long and I have Proficy already.

I am not yet sure If I will be using thermocouple input cards or analog input cards. If I find sensors/transducers with a 0-10V output or straight up variable resistance I will use the analog cards, else I’ll have to source a thermocouple input card.

I like the analog because I have a couple of 16 channel analog cards which will accept 0-10VDC or 4-20ma current. I am also looking for some vacuum transducers (saw some somewhere, cannot remember where) and an airflow sensor (thinking about using older modified automotive analog MAF sensors).

I want to know the temp, vacuum, and airflow at all of the various stages of the unit, so that the PLC can alert me when there are “abnormal” conditions present in the system.

I’m also liking water level sensors (still thinking on a tar level sensor - little more difficult) and some automated drain valves for Michigan’s cold winters (trying to prevent freezing and of course, kneeling or lying down in slop).

I definitely have a lot of work to do!


Hi Henry,
You certainly have your work cut out for you !!! It will be awesome to bring all of these sensors into one main computer and have it report back to you the conditions of a gasification system. This is one of the side projects I have been working on I will help in any way I can. This t-probe company makes a lot of gizmos I just used the millivolt because I all ready had the controllers to go with them. I was thinking about using automotive map sensors for vacuum. And your idea on using a MAF to monitor airflow is great I see no reason that would not work. Keep at it Regards Sean

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Hey HenryA.
Thanks for the experienced heads up on the PLC brand world.
Auto MAF’s be fine for the primary air flow.
Produced wood gas flow however . . . . anytime it is intruded, diverted or cooled at all it want’s to drop out slightly acid condensate and CO to CO2 revert dropping out a carbon soot particle. Whether you go with hotwire, sonic (Karmen Vortex) or VAF (flapper door) these contaminants are going to corrode and weight/coat deposit and throw off your calibrations.

Any body close you could work with a running woodgas system to see all of this?

Steve Unruh

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This is good information!

Terry Grzyb is the only woodgas driver I know of that is “close”, I think he’s over west (ish) of Detroit, but otherwise nobody I know of nearby. I “Hope” to have my truck together by end of summer (if the remaining build videos go online in time). I have the truck (Chevy 2500 with a 7.4L 454) & plasma cutter (Lotos LTP5000D) purchased and am still researching welders (I believe I am going with the Millermatic 180) then it’s full on construction until I’m done (I have the summer off). I intend to duplicate Wayne’s system and after some operating experience slowly integrate advanced monitoring and automation (learn to walk, then attempt to jog).

It is possible, that if I am accurately metering incoming cold air (Flow, temp & density), + I know the internal temp of the unit, + the vacuum being pulled by the engine I can compute the amount of gas being produced, otherwise I may not be able to monitor produced gas flow. Might need a special sensor for these (or a REALLY cheap & readily available 'er replaceable) unit with a housing that allows for easily maintenance or replacement. Monitoring produced gas flow may well be more headache than it is worth but I plan to attempt it at least even if it is abandoned later on as fruitless (love a challenge).

I will have to research the industrial world for corrosion resistant or self-cleaning (wouldn’t that be great) air/gas flow sensors. So far I have found a vacuum transducer that should work (ordered one today for bench testing). Sean is on to something with those thermocouples if we can interface them with the PLC (which I need to research further). And I have yet to research water level sensors for the condensate tanks.

Hi Henry,
On the water level sensors how about a simple float switch ??
These are used on boat bilge pumps all kinds of nasty things are in a boats bilge.
If that switch can live in that environment a woodgas condensate tank should be no problem.
This switch will give you a normally open/ normally closed reading.

If you are thinking about a level indicator how about a gas tank sending unit
you would clearly see 1/4 1/2 3/4 to full. wouldn’t that be sweet.
Just some thoughts Regards Sean

I like the gas tank sending unit… They are basically a float driven potentiometer.

A few concerns though; Unlike gasoline the wood gas water will likely be corrosive, not sure how long it would last. Of more concern, most (that I have seen - GM’s) are completely uninsulated as gasoline is not a conductor of electricity. The condensate mixture may have some electrical conductivity (affecting the reading). Any chance you could test some next time you drain your system? If it’s not conductive we have a winner.

Also considering RV tank sensors,… the blackwater level sender should be able to withstand just about anything short of pure acid I would think? I even considered using an RV blackwater tank but they are all plastic nowadays, and I don’t know that it would hold up well… might even melt if the gas was warm enough but the sender could be useful in our condensate tanks.

Hi Henry,
Yes your on the right path. We had some weird things happen to our first wood truck but it was an all around
junker so we already tested the condensate it is mildly acid with no conductivity. I would recommend finding
a sending that is insulated or protected from corrosion. The rv sending unit in black water might be the way to go
magnetic hall sensor comes to mind. I toyed around with the plastic condensate idea for awhile haven’t done it yet. Would have to be high temp A.B.S. plastic I don’t think a rv tank would be beefy enough by itself. I don’t see it melting unless something is wrong with the system but vacuum combined with mild heat could = crushed tank.
Regards Sean

allelectronics has sealed float switches i used 3 of them on a fuel tank at the lab 1 lite= refuel 2 lites half full 3 lites full mine also fed the pc that did the actual fueling


I think I’m liking this for liquid level measurement;

These could be used to drive analog gauges (old school) an can be wired to provide an analog input to a PLC or other micro controller. I may request a quote (they don’t provide prices, that’s usually a bad sign) but if need be this is a fairly simple DIY build (compared to the actual gasifier!). Build it with stainless tubing and it should stand up to corrosion just fine.

Hi Henry,
That’s exactly what I had in mind when I said magnetic pickup sensor Awesome find

A little help if possible we have a good thread going on instruments. I am going to ask if anyone here has access to a gas analyzer for measuring a wide variety of gases? Hmmm flamable and non flamable Regards Sean

Hi SeahF
There is much used automotive equipment out there for cheap and even sometimes free haul-a-way.
Be care.
Old, Old two gas only able to measure CO and HC’s
Old three and four gas pick up CO2 and O2.
Newest five gas stuff picks up NOx’s - nitrous oxides.
Old, old equipment was always expensive to keep running and use.
90’s manufactured 3 and 4 gas stuff not to bad if still manufacture supported.
ALL take special to buy “Calibration Gas” composed of precisely mixed CO, CO2 and HC (usually methane or a propane) to be able to verify your machine to measure and quote live gas composition with any accuracy.

Then there is the combustion Furnace world grade stuff.
Lab grade stuff.

Steve Unruh

I have the vacuum transducer now, (Transducers Direct #TDH31BGV01503D004) as well as (2) WIKA vacuum gauges and (2) temp gauges. I plan to construct a simple manifold with the WIKA gauge and the transducer on it very shortly and verify the readings are properly scaled and usable using a vacuum pump for my bench test. I will let all know how it works. If this works well, I’ll probably play with either buying or building the float switch we talked about above, and then the thermocouples and flow meters. Not sure why I started with the vacuum transducers but that’s where I started.

Interestingly, the Music City Metal temp gauges are oval in shape. From the videos it looks like Wayne has round gauges, did I get the wrong gauges or did I just not notice the oval shape while looking at the photos and videos?

Hello Henry,

The temp gauges I use are oval and should have been under ten bucks.

Thanks Wayne, those are the ones I have.