Oxalic Acid Vaporizer - Part II

I posted some info a while back on my attempts at building a homemade oxalic acid vaporizer and thought that I would provide an update on my progress.

Formerly I tried using a small tuna can and a diesel glow plug. It worked OK, but the heated interval was too small and I just didn’t get the amount of vaporization that I was looking for. I am looking for a unit that I can place beneath the screened bottom board of my hives and emit a nice cloud of vapor that will waft up. The tuna can setup just kind of fizzled – not really enough to treat a hive.

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I then tried a couple of different household items that may work. Wife’s candle melter? Sure, why not? Why the heck doesnt she just light the candles like you are supposed to anyway? I actually got some vaporization, but the temperature was way too low to get much (good thing for me). Note; You can see a partially dismembered heat controller/probe that I retrieved from my wife's electric fondu pot in the lower right corner. I tried some rigging with it, but did not try to test it.
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Next up, the old coffee pot in the basement. I made quick work of tearing the guts out, obtaining the heating disk and re-wiring without all of the controls. This worked really good. Not hot enough to thermally destroy the OA, but enough get good vaporization. I also liked the nice large and flat surface area to place the OA on.

Looking good (note it is hard to see the vapor in the picture, but rest assured there was plenty).

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Next, off to the hives. The worst part was dragging 200 feet of extension cord (the tuna can ran on 12 volt DC, which was nice). Again the pictures do not come out so good, mainly because the vaporizer was placed in the dark recesses underneath the hive. My hives are up on cinder blocks and the was a slight breeze, so I took a long sheet of poly plastic and some bags of mulch to seal off the area under the hive. This setup worked good enough to keep most of the fumes where they need to be and not vent to the atmosphere. After I was sure that I got good vaporization, I closed up the front of the hive with more plastic and let her rip.


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The results? Hello OA and goodbye mites! Yeah me!


HA!, Die you lil’ bastards!
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Nice,Ill have too give it a try.Looks good.

I dont think the mites like it! It does take a bit of fiddling around to get just the right amount of heat, the right temperature and good contact with the Oxalic powder. I may give mine its first true run inside the hives tomorrow if it quits raining. It should fit right in the entrance. I have used a years worth of acid doing test runs. Nice how cheap it is!

Crofter, is yours a homemade system? Please elaborate.

Yes, it is home made.

This prototype seems to be quite workable. This uses a pair of glo plugs but one would work if you kept size down to a minimum. The unit is low enough to slip entirely in through a standard entrance, but the pan is much larger than necessary so I could easily cut down further on mass and reduce the warm up time. The aluminum conducts the heat well so does not leave cold spots for the oxalic to congeal against; nice clean boil off!

Warm up time was one minute before powder melted to a liquid and started to gas off. One minute more with power on then cut power and there is enough heat left to finish the evaporation in the next thirty seconds. You only have to cool things off a wee bit in order to refresh the powder as there appears to be no fumes from it even though the pan is too hot to touch. Have not tried repeat times.

http://www.youtube.com/watch?feature...&v=ALHz4B1vqKo


gets interesting around 3:15

Quote:

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Originally Posted by Nabber86

The worst part was dragging 200 feet of extension cord (the tuna can ran on 12 volt DC, which was nice).

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Would it be possible to run it with an inverter and a 12 volt battery?

Quote:

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Originally Posted by crofter

Yes, it is home made.

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Is that cast aluminum? It looks professionally made. Much better than my contraption.

Quote:

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Originally Posted by crofter

The aluminum conducts the heat well so does not leave cold spots for the oxalic to congeal against; nice clean boil off! Warm up time was one minute before powder melted to a liquid and started to gas off. .

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I noticed liquifaction, then vapor, then crusting over. When it crusts over, the vapor stops. I have to reach under the hive and stir the residue with my hive tool to get vapors again.

Quote:

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Originally Posted by ralittlefield

Would it be possible to run it with an inverter and a 12 volt battery?

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I could try that, but the element in the coffee hot plate uses resitive heating and I dont know how much power that would draw fom my battery. I could drive back there with my truck, I guess.

You can run the glow plugs with a battery charger. I find it easier to run an extension cord to the hives then to mess with taking the truck to the hives or taking a heavy battery. Obviously this does not work for out yards but, works pretty good at the home yard.

Just checked my coffee maker and it is rated 975 watts. To get 975 watts from 12 volt would require roughly 80 amp current draw by the inverter. Need fairly heavy wire between battery and inverter. On 120 V the current draw is only ~8 amps. Each glow plug would draw roughly 150 watts. The coffee hot plate is more than enough wattage but the heated area is a bit large. The target temp. for the diffuser is +320F and the coffee maker 100 or so deg. lower so may explain the problem of crusting over. I experienced that with the stainless steel cup of one of my experiments. Ideally the temperature of the cup should be fairly narrow and even between 320 and 350 F. You dont want to overshoot too much as the 0A crystals then flash to Formic acid, water, and carbon monoxide instead of Oxalic acid vapor you want.

When using glow plugs you really should not have the vehicle running as the alternator voltage approaches 15V as opposed to little more than 12V under load from the battery. You might get away with it for a while but the glow plugs generally designed for a nominal 11 volts. Some heavy duty chargers could have the same effect.

The stock for my heater came from a chunk of 3/4 thick aluminum plate. I rough turned the ID of the bowl on the lathe and the balance of the metal removal was with cut off wheel on angle grinder and die grinder. Being once upon a time a steamfitter and welder they come to hand fairly easy!

Wow that is a lot of info. I am saving it to a file for future reference (I may have to read it a few more times to catch it all).

Aluminum. Nice even heat. I like that idea. I will have to get me a piece of scrap and try it out myself. I am sure that I can find a way to gouge it out enough to make a shallow bowl. I take it that you drilled and tapped the holes for the glow plugs.

Actually i turned the threads off the plugs and they are retained by the set screws visible down through the top. 5/16 X 18 tpi. In their intended use the cyllinder pressure could be 1500psi therefore the threads and tapered seats. Not needed in this use.

just want to thank you guys for the updates.I really like this method. I have used the electric Heileser model,but have been follow your posts. thanks very much. I just need to be able to treat a whole pallet at a time. then while one pallet is being treated i could be removing the vaporizers from another pallet. mthanks for the updates.

GB

Can you tell us your impression of the Heilyser vaporizer. Preheat time till vapor start and then till completion. I think it is a decent price since a single glo plug costs us around 21$ here in Canada.

The Heilyser look like about $90 US (plus shipping). So far I have about $20 in my prototypes. Glow plugs go for about $10 here, but could probably get another one for $2 at a junk yard. All I need now is a scrap piece of aluminum.

Crofter, you setup looks close to the Heilyser. Is that were you got the inspiration?

I have had good luck with my elec heileser, I think about 1.5 min. is all i need to completely vaporize the oxalic. trouble we have here in Arizona is that we stay warm so late in the year. seems like it is about halloween before we cool of and stay that way. I really hurt my hives 2 years ago using apigard, last year I used hopgard in colorado before returning to Az. I would like to have a total of eight vaporizers so I can treat my hives alot faster. I am just under 400 hives and plan to continue growing for a while.leaving this saturday for colo. to ship the girls home. I will have to work on the Oa system this winter.I would put a genny on the bed of my 550 and run a electric cord to the various pallets. I will have to talk to someone to find out what the proper wire size etc would be as I dont know beans about electricity. thanks for the posts guys your alot of help. GB

Has anyone tried using a heat gun run off a generator? The big drawback with oxalic vaporizing is the slow time to reload and do a lot of hives in a reasonable amount of time.

What about this video? Other than getting blasted by all the nasty fog(gas mask a must) , it looks like a quick and dirty way to get a lot done.

http://www.youtube.com/watch?v=RcKyE...ature=youtu.be

Or how about this ingenious set up?
http://www.youtube.com/watch?v=FtITG...eature=related

I guess that shows that there are several ways to deliver vapor. I really like the bicycle pump and hose set up. I haven't made a heating element small enough to fit in a hive entrance. The plastic tube would be really easy and with the vapor generator outside of the hive you could you could build a big one that will hold a lot of OA. I will have to work on that.

Here's your next project. http://www.eng-service.com/guarda%20video.htm