# Oxalic Acid Vaporizer with Temp Controller



## BeeAttitudes (Dec 6, 2014)

I finally finished the vaporizer I've been working on. Here are the features I added:

- Separated handle mount from aluminum body to minimize heat transfer
- Added a 350F Thermo Disk to cutoff power to the glow plug after OA has vaporized
- Added a light by the handle that is lit when the glow plug is powered. When the OA has finished vaporizing and the temp raises to 350F, the light is turned off so you know it's done (no timer needed).

I don't have a mill so everything was done on my drill press and it's not pretty, ha. Here are some pics if they upload from my phone ok.

























Here is a link to a video of the vaporizer in use and you can see the light turn off when the OA vaporization completes. I've only ran this one test so I'm sure more testing is needed.

http://youtu.be/q7SSPU4dlBo


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## WWW (Feb 6, 2011)

The vaporizer does work well, good job. :thumbsup:


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## shinbone (Jul 5, 2011)

Automatic power shut-off and a light indicating that the OA has completed vaporizing are nice features!


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## gweloboy (Mar 28, 2015)

What size Aluminium did you use? Buying the aluminium is a problem in our area
What glo plug did you use?

I am thinking of making one in my lathe, using the 4-jaw chuck to offset the crucible.

Cheers


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## BeeAttitudes (Dec 6, 2014)

That glow plug is an AC Delco 60G. I used 1/2" aluminum plate. You can buy it on eBay and have it shipped to you as cheap as I could buy it locally.


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## Brad Bee (Apr 15, 2013)

Where did you get the Thermo Disk? I am a lot of things, but I am NOT an electrician. Would you mind providing a wiring diagram that I could use, please? I like the looks of your vaporizer.


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## Denniston (Mar 19, 2015)

Great job BeeAttitudes. I love your modifications to the standard vaporizer. I'm a little bummed now that I reread your thread and see you were able to make yours out of 1/2" material as I already ordered 3/4". Oh well, it was cheap. Any way, I was wondering about the glow plug, does that need to be tight (making contact with the aluminum), or if it is just threaded into a deep hole will that work?


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## BeeAttitudes (Dec 6, 2014)

Here is a link to the thermo disk I used:

http://www.alliedelec.com/selco-or-350-qc/70098625/#tab=specs









I'll have to make a drawing to show the wiring but it is very simple.


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## BeeAttitudes (Dec 6, 2014)

Denniston said:


> I was wondering about the glow plug, does that need to be tight (making contact with the aluminum), or if it is just threaded into a deep hole will that work?


I'm not an expert on glow plugs but I'll give my opinion. A glow plug has the body and the heating element. Ideally, I would want the heating element portion in a hole sized so it makes contact around the entire perimeter and length of the heating element. However to do this, you would need essentially a press fit........and I wouldn't want a press fit as it might damage the heating element and I want to be able to replace the glow plug easily if needed. A hole 0.002" larger than what will be inserted is still considered a press fit.......so I would want a hole just larger than that, say 0.003" - 0.010" larger than the diameter of the heating element. And then I used set screws to hold the heating element tight against one side of the wall as there is more heat transfer with conduction than convection (passing heat across an air gap). Also, these set screws ensure the glow plug is grounded properly. 

No need to insert the body of the plug into the aluminum block as it just adds a heat sink and might cause your heat plug to fail more quickly (some would likely take the heat better than others). I only drilled deep enough for the heating element portion of the glow plug to make contact. From the videos I've watched it appears heat is concentrated near the tip of the heating element so keep that in mind when deciding the location of the heating element in relation to the cavity holding the OA.


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## BeeAttitudes (Dec 6, 2014)

Here is the video linked above but embedded so you can watch it here. Note I have the hood of my truck raised and the vaporizer is laying above the radiator but not sitting level.


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## BeeAttitudes (Dec 6, 2014)

I'll try to show a couple of the early drawings. Drawing before I cut the handle mount away from the main body (cut in the hashmarked area). Note I made the cavity 3/4" wide, not 1/2" wide as shown in these drawings. This made the block 1/4" wider than shown (1 3/4" wide). Also, I used a 13/64" drill bit to drill the hole for the glow plug heating element, not 15/64".










Assembly drawing: Note, I ended up using 1/4" X 20 all-thread, not 5/16". You can see the wiring.....the power runs to one side of the thermo disk then comes off the other side of the thermo disk to the plug. I also ran a wire from the glow plug side of the thermo disk back to power the light so the light would cycle on/off with the glow plug. The wire going back to power the light is the blue wire in my pictures/video.


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## Brad Bee (Apr 15, 2013)

Thanks for the info and the drawing. I think I can even wire that up! LOL 

With those acidic fumes getting ahold of it, your hood may fall off your truck in a few weeks.


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## Roland (Dec 14, 2008)

Have you thought of drilling the glow plug hole at the junction of two pieces of aluminum, separated by a piece of paper bag? That way, when the paper is removed, the two pieces of aluminum could be bolted together and have near 360 degree contact with the part of the glow plug that gets hot. That is how we clamped heating elements on packaging equipment that sealed plastic. I believe doing so would increase the life of the glow plug.


Crazy Roland


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## brownie2 (Nov 20, 2014)

How long does it take to cool between hives? Can you dip it in water? Will it hold 2g?

This is my favorite homemade vaporizer yet!


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## BeeAttitudes (Dec 6, 2014)

I made the cavity 3/4" wide (not the 1/2" wide shown on the plan I posted) and then it holds 2g fine. I'm using 2g in the video I posted. You can see that it bubbles over the side a bit when vaporizing......but the block wasn't sitting level either.

I didn't time how long it took to cool between hives but I'm sure it's about like every other design. One nice feature is that since you don't have to depend on a timer, you don't have to let it cool down completely.......just cool down well below the point where the OA turns to liquid. The light will still tell you accurately when it's done (reaches 350F). This would mess your timing up if you use a timer to determine when you're done. 

I can't think of a reason you couldn't dip it in water if you would rather take that approach........just make certain the power is off.


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## Denniston (Mar 19, 2015)

BeeAttitudes said:


> I made the cavity 3/4" wide (not the 1/2" wide shown on the plan I posted) and then it holds 2g fine. I'm using 2g in the video I posted. You can see that it bubbles over the side a bit when vaporizing......but the block wasn't sitting level either.
> 
> I was wondering how deep you milled your cavity? Actually what I'm wondering is, what is the preferred volume of the cavity?
> 
> Thanks


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## BeeAttitudes (Dec 6, 2014)

My cavity is 3/8" deep.

Well, 2g Oxalic Acid is about 1/2 tsp = 0.1504 cu. in.

3/4" X 1 1/6" X 3/8" = 0.75" X 1.0625" X 0.375" = 0.299 cu. in. You will actually have a bit less than this using a round bit to create the corners (rounded off as opposed to squared off). This isn't quite twice what is needed but large enough and hopefully large enough to handle 3g if the need arises (not yet tested).

0.1505 cu. in / 0.299 cu. in = 0.5033 So about 50.3% filled. With my cutting errors and rounded corners, I would guess my cavity is roughly 60% - 70% full with a 2g dose of OA. If you think you will treat using a lot of 3g doses, you might consider making your cavity larger. Remember that the bubbles create additional volume you want to contain.


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## crofter (May 5, 2011)

See how you make out with that size. I found that I needed more room than that to keep from overflowing when the charge gets to bubbling in the boil off water stage. I know at least one other user found that definitely the case too, when he tried to vaporize a quantity scaled for three deeps.


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## BeeAttitudes (Dec 6, 2014)

I think you are correct Frank.....this may not be enough for a 3g (3/4tsp) charge of OA.

Does anyone know if a 2g charge followed by a 1g charge is as effective for 3 deeps as is a single 3g charge? I'm unsure how common it is to utilize a 3 deep brood nest. If it's not common, then maybe two 1.5g charges would work in lieu of a single 3g charge. Thoughts?


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## MT204 (May 12, 2011)

This instructions I got with my JB2000 vaporizer state "1 scoop(gram) of OA per 10 frames of bees/deep box".


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## JConnolly (Feb 21, 2015)

I'm just wondering, since I have screened bottom boards and a small lab type hot plate, wouldn't it work to just set the hot plate under the hive with the SBB open and vaporize the oxalic acid with it?


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## crofter (May 5, 2011)

I think it would be overall too much heat input. The vaporizers are 150 watts or less.


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## johnmckeag (Dec 7, 2013)

Is this a DC or AC powered temp controller? The specs show it is 250 VAC. Thank you for this fantastic design and imformation!!


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## johnny9 (Aug 5, 2015)

very nice design. One question and please understand that I am not electrically inclined at all. I see when you have the hot wire running to the thermo coupler then onto the the glow plug and have 1 wire doubling back to the led off the outlet side of the thermo coupler but where is the ground wire attached. I don't see it in the video or the drawings.????


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## svtkpr (Mar 16, 2011)

In the first picture you can see a yellow crimp-on connector by the handle that is where the ground or negative is connected. The body of the vaporizer is the ground path for the glow plug.


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## johnny9 (Aug 5, 2015)

Thanks I got it not see told ya I wan not electronically inclined If i were I would have know that lol. Thanks again for the clarification


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## BeeAttitudes (Dec 6, 2014)

johnmckeag said:


> Is this a DC or AC powered temp controller? The specs show it is 250 VAC. Thank you for this fantastic design and imformation!!


Sorry I just now seen your question John. It is a DC powered temp controller. The thermal switch will work with both AC and DC but has a longer life when used with AC. No problem though as it will last a long time at 12V DC.


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## duff112 (Aug 27, 2015)

Hi, i have been making something similar, although I'm struggling to reduce the voltage to the glow plug to prevent it burning out. Have you used an inline resistor or potentiometer? From what i've read even the dual coil 'self regulating' plugs have an inline resistor?
thanks Mike


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## deknow (Jul 17, 2006)

I think you will want to vary the duty cycle of a pulse width rather than reduce the voltage...pulse width modulation (PWM).

you need a little bit of electronics...probably easy to use an Arduino and some existing code.

I just came up with a brilliant plan for vaccuum tube vaporizers....for that vintage sound!


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## texanbelchers (Aug 4, 2014)

deknow said:


> vaccuum tube vaporizers


Some of those babies may have gotten hot enough.


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## Harley Craig (Sep 18, 2012)

gweloboy said:


> What size Aluminium did you use? Buying the aluminium is a problem in our area
> What glo plug did you use?
> 
> I am thinking of making one in my lathe, using the 4-jaw chuck to offset the crucible.
> ...



just make your own https://www.youtube.com/watch?v=lSoWxG30rb0

no need for a mill either. just drill the final hole for the glow plug. https://www.youtube.com/watch?v=tH-PaNugz9w


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## BeeAttitudes (Dec 6, 2014)

Harley, that is a great suggestion! Thanks.


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## Harley Craig (Sep 18, 2012)

BeeAttitudes said:


> Harley, that is a great suggestion! Thanks.


of course putting all that stuff together is probably more expensive than buying a hunk of aluminum and going down to the local fab shop and have them mill it. Do ya still have local fab shops around? LOL


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## Arnie (Jan 30, 2014)

That is cool. Thanks for posting.


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## Denniston (Mar 19, 2015)

Has anyone seen or compiled a list of resources of what glow plugs would work / interchange, and what thermodiscs and where are the cheapest sources to purchase?


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## mcifrani (Feb 9, 2016)

Hey there, What dimension is that block? I know it is 1/2 inch 

Mike


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## BeeAttitudes (Dec 6, 2014)

Dimensions are given in post #11 of this thread.


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## mcifrani (Feb 9, 2016)

Yes! right after i posted a reply, I saw your dimensions. Very nice! I printed them and got the thumbs up from the wife!

Mike C


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## rv10flyer (Feb 25, 2015)

As an hvac guy, I too thought about temperature control using a limit switch. I doubt that switch will take the corrosives bubbling over on it or the dipping in water cool-down for long. A stainless shielded thermocouple like those used for aircraft cylinder head temperature measuring would last much longer, although too expensive including a controller.


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## Rader Sidetrack (Nov 30, 2011)

The vaporizer that post #39 is referring to is only 40 watts! 

A more typical OA vaporizer is around 150 watts. Don't waste your money on this imitation.


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## Phoebee (Jan 29, 2014)

I am about to do something like that for my Varrocleaner (the one Brush Mountain carries). I've used it once and have decided it gets way hotter than needed, very fast. They say it will melt down if you leave it on too long. One of my concerns is that the thing could get hot enough to scorch the bottoms of frames.

Since I already had the parts on hand to build a 12V incubator controlled by a precision PID temperature controller for transporting queen cells, and the solid state relay is rated at a whopping 40 amps, I'm about to add a thermocouple to my Varrocleaner and turn it into a precision-regulated vaporizer. I need to finish up one project and then I'm on it.

My temperature controller is a JLD612DC, designed to run on 12 VDC. There are cheaper digital thermostats that would do the OAV job OK, but this one is a full PID controller with autotuning, which I prefer for the incubator application. Most solid state relays are AC only, but you can find DC models if you look. The controller works with a wide variety of sensors, including the K thermocouples I use extensively. I got the controller and SSR on e-bay.

I have worked with high-current thermodiscs in the past. The Varrocleaner pulls a bit over 10 amps and I don't entirely trust thermodiscs at such high currents, expecially DC.


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## oldfordguy (Dec 5, 2009)

I put together a vaporizer w/temp control to use on my top entrance hives that slides in place of the bottom board for treatment that I used last season for my hives, and it worked better than I hoped for. I'm going to replace all my bottom boards with ones that this vaporizer will fit. If anyone is interested, here are some details and the video of me testing it: http://mannell.net/?p=89


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