# Significant inconsistencies or issues using the PRO VAP 110



## Jack Grimshaw (Feb 10, 2001)

Sounds like your temp is too low.What do your directions say to use?

Googled sublimation temp of OA and got 315-372°F.
Could be liquifying and plugging your tube.


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## JWPalmer (May 1, 2017)

The provap temp controller reads in degrees Celsius. The range you see is similar to what I see with mine, Mine actually has shown 254 at times. But it stabilizes at the 230 if left alone. Only had a cap blow off once in three years but have heard of it happening to others too. Not sure if the tube got plugged with propolis or I simply did not get the cap on correctly.


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## wildbranch2007 (Dec 3, 2008)

sounds like your provap is working normal, does the same as mine does. have had caps multiple times, always my fault, if the tub hits a frame it will blow, I drill the whole between the two deeps and never have a problem, also clean the tube every once in a while, i do it once a day


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## rkereid (Dec 20, 2009)

Mine operates the same way that you describe. I've been using mine on about 200+ hives for three years. I've never had a cap blow yet. I did have an o ring break so I ordered extras. Great service got here in two days.


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## Grins (May 24, 2016)

Johno's blows it's cork sometimes too. I think its because the tube is too cool and OA precipitates as it passes through plugging it up. It happens to me on cooler mornings and letting the thing heat a bit longer between treatments seems to work well for me, that way the tube stays hot enough to not cause problems.
Yeah, I know, ProVap only..., I'll find my own way out.
Lee


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## rkereid (Dec 20, 2009)

I should have added that I wrapped mine on day one with muffler wrap using copper wire. That may keep it hotter longer, keeping the tube from clogging.


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## 123456789 (May 24, 2009)

I keep a small torch nearby and heat the stem every few hives to keep it clear. It can be plugged tight and poof the heat clears it.


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## ifixoldhouses (Feb 27, 2019)

Wrap the bowl with muffler wrap, never had a problem since I did it.


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## beebad (Mar 28, 2019)

Thanks for the responses.
thanks for feedback on temperature concern.

I have warm way bases made from 2x10’s and the provap stem was not making it into the base’s cavity. The molten OA was plugging up the narrow 1/4” channel and would impede the vapor and other times block it enough to cause the pressure to build and pop the cap. ( i bought extra caps so i could just go down the line and treat)



https://www.lowes.com/pd/BLACK-DECKER-5-Pack-Twist-Drill-Bit-Set/1003014314?cm_mmc=shp-_-c-_-prd-_-tol-_-google-_-lia-_-215-_-pta-drillinganddriving-_-1003014314-_-0&placeholder=null&gclid=CjwKCAiA_Kz-BRAJEiwAhJNY72m8LUA5QM5UDML8FFH5tctx_l8yWaMAiO5fGtcW-ejQdZ12JH178RoC5FYQAvD_BwE&gclsrc=aw.ds



i had to go in and auger the hole a little from the inside until i could feel the tube of the provap when inserted.... I will have to go in and do this to two other hives. This should fix my issues.

i think most people just go through the typical thickness of a hive box instead of what i do. Thanks for responding.


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## beebad (Mar 28, 2019)

wildbranch2007 said:


> sounds like your provap is working normal, does the same as mine does. have had caps multiple times, always my fault, if the tub hits a frame it will blow, I drill the whole between the two deeps and never have a problem, also clean the tube every once in a while, i do it once a day


I clean it after every use. Having that cap pop was not cool especially if there is molten OA still on it. The last treatment was the final straw before i went in to look closer at why this was happening. i had noticed a blug of molten OA on the tip.... once that molten OA cools it is like glue. i would reinsert the golf tee right after treatment and then four days later rhe tee would almost be impossible to remove. Then it occurred to me was was happening.

btw, the hole is below the base’s screen, and above the IPM slot. When i read the varroa drop 48 hrs post treatment i will usually find a blob of solidified OA on the IPM board.


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## Sean Govan (Jul 9, 2018)

I beveled the end of my tube with 150 grit so it won't blow when it butts up against a frame.


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## JWPalmer (May 1, 2017)

If you are pushing the OA vapors through a screen, most of the crystals are adhering to the screen and not making it into the hive. You might be better off vaping through a hole drilled a few inches up from the bottom on the narrow side of the hive body. Just pay attention to frame location.


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## beebad (Mar 28, 2019)

JWPalmer said:


> If you are pushing the OA vapors through a screen, most of the crystals are adhering. to the screen and not making it into the hive. You might be better off vaping through a hole drilled a few inches up from the bottom on the narrow side of the hive body. Just pay attention to frame location.


I was afraid someone would say something when I used the word screen without saying what it was. It is , industry standard 1/8” hardware cloth that they use for bottom boards and so on. I have used OAV a year before it was legal and had to go through the front entrance and with out the drawn out detail, one little golf tee hole where mine is, is infinitely easier. I should attach a picture of one hive setup that shows the base with the gold tee.....very convenient for me. The front entrance can be seen there. The long slat on the upper right hand side with dual wing-screws, below the screen is the opening for the IPM board and the hole for the golf tee is opposite the front entrance between the screen and level of IPM board, that wasnt drilled yet. You can just see where the iom board slides in and fits to seal off the base. You can also just see a cookie sheet filled with mineral oil for SHB. WHATEVER falls thru the screen and doesnt drown stays down there because everywhere else, there IS window screen That you cannot see For ventilation.






found a random image of front of base and vent screen.


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## John Davis (Apr 29, 2014)

What JW was referring to was not that the screen was too fine. The sublimated OA recrystalizes as soon as it cools below the sublimation temp. The wire of the screen acts as a heat sink so often you get build up on the screen which means that what is on the screen is not getting where you want it. Folks that use a pan type vaporizer under the IPM screen sometimes report that their vaporization was not effective not realizing why.


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## beebad (Mar 28, 2019)

John Davis said:


> What JW was referring to was not that the screen was too fine. The sublimated OA recrystalizes as soon as it cools below the sublimation temp. The wire of the screen acts as a heat sink so often you get build up on the screen which means that what is on the screen is not getting where you want it. Folks that use a pan type vaporizer under the IPM screen sometimes report that their vaporization was not effective not realizing why.


I understand what you are saying, but it appears that JW was indeed concerned that the screen was too fine and trapping the majority of the gas produced and this simply is not what is occuring, at least not in my apiary. Besides, metal will absorb heat quicker than wood and surrounding wood frames, so I am not convinced condensation is a significant concern. I vaporized 2g and 1g of OA when i first got the unit to get a sense of the rate of sublimation. One thing I noticed was this. If the nozzle is not obstructed in any way, the rate of the emerging cloud of oxalic acid occurs almost at once, so any localized condensation within close proximity to the nozzle , imo, would not effect the dispersion of this gas to permeate hive being treated. 1g is almost enough with the PV110. More OA is not necessarily better and may contribute to the excess blobs of OA. I used 2g with the battery powered paddle type vaporizers and continue with the PV110.


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## JWPalmer (May 1, 2017)

Sorry beebad, but I never even considered that there was something finer than 1/8" hardware cloth as your bottom screen. John Davis presented my thoughts exactly, the screen act as a heat sink and a significant amount of the OA solidifies on the wires. I vape through a hole in filler strip at the back of the bottom board. Even still, some of the OA ends up on the screen below. I also use a bit more, a rounded 1/2 tsp. which is approximately 3.5g. I have inserts in but make no attempt to seal up the openings. There are still crystals swirling around after several minutes. Been using exclusively OA now for three years.


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## beebad (Mar 28, 2019)

JWPalmer said:


> Sorry beebad, but I never even considered that there was something finer than 1/8" hardware cloth as your bottom screen. John Davis presented my thoughts exactly, the screen act as a heat sink and a significant amount of the OA solidifies on the wires. I vape through a hole in filler strip at the back of the bottom board. Even still, some of the OA ends up on the screen below. I also use a bit more, a rounded 1/2 tsp. which is approximately 3.5g. I have inserts in but make no attempt to seal up the openings. There are still crystals swirling around after several minutes. Been using exclusively OA now for three years.


Window screen is much finer than the 1/8” wire mesh screen you see in the picture, if you are using more than the recommended 1g per brood box, you may see more OA deposits, which makes sense. When i partially dismantled the screen to gain access to auger the hole from the inside there was not a build up of condensed OA on the screen, except where the hole was on the inside of the base before I enlarged it. The hole is a few inches below the frames and the screen but above the IPM board-win win. The screen is not an issue over here but thanks for mentioning it. I am just following best bee keeping practices using OAV. It is all i have used as a final treatment of the year for 5-6 years. I would love to not seal the openings but I wont do that, i like 10 mins. All in all the PV110 is such a time saver. Thanks to everyone for your responses!


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## beebad (Mar 28, 2019)

I went in today to auger the holes for the PV110 from the inside of my base. I have performed many OAV treatments in the last few weeks and there was not a build up of OA at the screen directly above the PV110 orifice hole....I did see where the outlet/orifice was partially blocked and the OA built up right there, thus the reason to go in and enlarge the hole from the inside. There is, however, a light coating of what I assume is OA above the hole but after 4 treatments, this artifact is inconsequential.


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## wrass (Nov 16, 2017)

OA absorbs moisture from the air. The more moisture, the more the tip cools and builds clogs during sublimation. Slows down the process and makes things dangerous. 

Dry your OA and things will go much better. I bake mine below the sublimation point for several hours. 185F seams to work in my oven. I then store it in smaller, sealed containers.


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## JWPalmer (May 1, 2017)

Very good point. I only remove a small amount from the bag at a time and keep it in an airtight container, a small mason jar with lid. The big bag is also zipplocked and then stored inside another zipplock bag. The FL Labs product seems to work the best for most people and is not at all expensive.


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## beebad (Mar 28, 2019)

wrass said:


> OA absorbs moisture from the air. The more moisture, the more the tip cools and builds clogs during sublimation. Slows down the process and makes things dangerous.
> 
> Dry your OA and things will go much better. I bake mine below the sublimation point for several hours. 185F seams to work in my oven. I then store it in smaller, sealed containers.


Really? “Slows the process down and makes things dangerous”, you mean like baking OA for several hours, in your oven?

Oxalic acid is a dangerous compound to bring into a kitchen to heat up like that, perhaps if I had a laminar flow hood, but that is just ....well you know..... I would not do it. More dangerous for the layman.....I would definitely not try this at home for anyone else reading this *****. *it is very dangerous and unnecessary.

I don’t think moisture, the way you are describing, is much of an issue at ~230C.

What makes you make that statement....where do you get your information about moisture?

Under a typical RH (10-90%), *oxalic acid* hardly deliquesces and exhibits low *hygroscopicity*, So can you share your source of information, because it just doesn't jive with the CRC.

but, thanks for responding


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## JWPalmer (May 1, 2017)

Beebad, it does jive with observed behavior. Like when I leave the little mason jar open too long and the next time I go to use it I have to break up the big chunk it has become. I know that it has absorbed, or maybe in this case adsorbed, some degree of excess moisture.
As far as drying it in one's oven at home, OA is cheap. If it got that bad, I would just buy another bag. I will save the science experiments to the things I find growing in my refrigerator


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## beebad (Mar 28, 2019)

mine cakes up to a degree but not to any consequence involving safety. that was not the question.


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## John Davis (Apr 29, 2014)

Beebad
Your arrangement has plenty of room for the OA vapors to recrystalize in air as it cools so the heat sink effect of the metal screen is not an issue. Making the opening larger also helps by limiting vapor contact with a cool surface.
The heatsink effect can be an issue especially if using a pan style vaporizer placed directly below the screen.
Looks like you have it under control.


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## wrass (Nov 16, 2017)

beebad said:


> Really? “Slows the process down and makes things dangerous”, you mean like baking OA for several hours, in your oven?
> 
> Oxalic acid is a dangerous compound to bring into a kitchen to heat up like that, perhaps if I had a laminar flow hood, but that is just ....well you know..... I would not do it. More dangerous for the layman.....I would definitely not try this at home for anyone else reading this *****. *it is very dangerous and unnecessary.
> 
> ...


Dangerous starts with using an organic acid for any purpose so everyone should be aware of that part. Placing said organic acid in heated vessel designed to sublimate (I will come back to this in a moment) this compound and rapidly eject the the vapor out of a restricted opening increase that danger. Now introduce the inherent design flaw in the popular closed style vaporizers and one that you witnessed, over pressurization during heating due to a clog with no pressure relief. That is dangerous. Do what you wish but i see slow, controlled heating of OA the a temperature that is over 100F less than the sublimation temperature, relatively benign. Having the lid to my ProVap blow off and liquid aqueous (more on this below) OA spray out with it is not so desirable. So, to each his own I guess.

I am, however, glad you can use Google but I would encourage and read more than only the highlighted section of the first search result that comes up. My source that I will quote is the same as yours. "however, transformation between anhydrous and hydrated particles was observed during the humidifying and dehumidifying processes". It goes on but if anyone else is interested, Google. 

Soooo, OA contains some amount of water. I have observed the process of sublimation of OA countless times while building an testing different styles of vaporizers. Randy Oliver describes the process that takes place so if I need a source for that try Scientific Beekeeping. " How does oxalic vaporization work? In the CRC Handbook of Chemistry and Physics we find that upon heating oxalic acid, the water of hydration boils off first, then at 315°F the oxalic acid starts to sublime". Dadant lists this temperature at 215F for water to leave the OA crystal. 

Now we get to sublimation. If you watch the process of heating OA to it's sublimation point, you will see a transition from solid to liquid. Since OA sublimates, the liquid cannot be OA but is in fact, hydrated OA as referenced by Randy Oliver or for fun Dadant, American Bee Journal, Bee Culture, or just about anything I have read or seen on the topic. The water must be driven off before sublimation can begin. So this is where the problem that you so quickly dismissed comes into play. The chamber cannot maintain the temperature with water boiling. Once the water is gone, the temperature rises and sublimation begins. The more water in the OA the more the temperature will drop in the chamber. The water exiting the nozzle cools it as well, causing buildup of OA crystal within, once sublimation begins. Left long enough, the system will heat back up and the crystals will clear. Try to dose too soon and the tube will clog. Too much water and you treatment will take a long time, your nozzle may clog and the cap may pop off. A big deal to me when I am trying to treat 100 plus hives.

This could explain some of the inconsistencies in your OA vaporizer performance. W A T E R. If you are using old wood bleach, I am pretty certain of it. FL Labs as JWPalmer suggested, is a great source for anhydrous OA.

So, I suppose I could have given this lecture in my first post but I was busy and cut it a bit shorter that this one. Also, I must apologize for responding to a question from a poster that obviously knows everything.

To everyone following along, try dry OA if you have problems sublimating.


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## beebad (Mar 28, 2019)

Thanks for all that.

But the reason I had one pop off because the holes were not flared out thru the walls on the inside and caused a blockage and subsequent build-up of OA.

There would be dozens of posts about the dangers of OA and moisture, as well as disclaimers on product inserts for various vaporizers. if this were an issue and it seems it is not, there would be a lot of chatter on the topic.

if you have a vaporizer that is NOT of the DIY flavor built at home then the temperature range for vaporization is dialed in.....120v vaporizers are pretty much set, but YOU could have a weak little battery that may fail to reach the required temperature vaporize the dose. A little moisture in the OA is inherent, but as I said earlier, is not an issue at 230+ centigrade.

I think we have waded far enough in the weeds from the OP, since I am wanting to hear from folks who ( 1.) Have the ProVap 110, (2.)- see inconsistencies in operation.

If you really feel that heating Oxalic Acid in your kitchen oven is not a dangerous thing to do, YOU should create a NEW topic in the section of your choice, and let's see what the community says..(bee brave?)...if nothing else, it could keep some impressionable newbie from serious injury.

thanks for responding!


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## wrass (Nov 16, 2017)

I do have a ProVap 110.

And I posted an opinion, an answer to you question. With the experience of operating it for two years now.. You are the one that asked for sources.


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## JWPalmer (May 1, 2017)

beebad said:


> There would be dozens of posts about the dangers of OA and moisture as well as disclaimers on product inserts if this were an issue and it seems it is not.


There have been several conversations in the past few years regarding the caps popping off and hot liquid spraying out. Because of this, goggles are recommended. I don't think much has been said about moisture being a contributing factor, but it seems plausible to me.


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## Meghues (Jan 5, 2016)

I have trouble when my bottom boards are soaked from recent rain. Some hives, due to orientation, get more than others. I think there is enough water in the wood to cool off the opening of the vap-snout, just enough to crystallize some oxalic acid at the outlet. Because a perfectly clear tube will plug up in seconds and blow the top. 
I’ve been reaming the tube and then inserting it hot and empty for a little steaming period. Then repeat with OA.
its a pain.


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## beebad (Mar 28, 2019)

Meghues said:


> I have trouble when my bottom boards are soaked from recent rain. Some hives, due to orientation, get more than others. I think there is enough water in the wood to cool off the opening of the vap-snout, just enough to crystallize some oxalic acid at the outlet. Because a perfectly clear tube will plug up in seconds and blow the top.
> I’ve been reaming the tube and then inserting it hot and empty for a little steaming period. Then repeat with OA.
> its a pain.


awsome.
The problem I had was the tube on the PROVAP 110 is not long enough to go through "two by" wood where usually this is designed to go through a "hive-box thickness" of 3/4". 

I had to go INTO my "warm Way" base and auger out the "hole" from the inside to give the "tube" an unobstructed avenue for the fumigation. (see pics above) 

I have since done 8 more vaporizations with complete sublimation.....no OA build-up on the inside anymore....nothing blocking the tube to build up pressures and so on. But who knows, over time, there may be some.... but I am at the tail end of my FALL treatments, but because the PROVAP 110 is sooooo convenient, I will use it more often as a knockdown.

But, I just don't see how a little bit of moisture at the end of a copper or brass tube will counteract the effect of 230 degrees centigrade blasting forth.

Happy Holidays!!!!


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## JWPalmer (May 1, 2017)

For clarification, oxalic acid sublimates at around 157 degrees C. The bowl is heated to 230 degrees to allow for the immediate and rapid sublimation of the entire contents. Water boils at 100 degrees C and the amount of heat (calories or joules) necessary to cause water to boil is considerable relative to other substances. The more water that is present, the faster the bowl, and the tube which has very little mass, cools to below the OA's sublimation temperature. Once the tube cools to below 157, the OA forms back into a solid. Contact with 1-1/2" of wood, or any wet wood, both of which act as a heat sink, would cause the tube to cool even faster.

Badbee, I am glad you figured out what was causing your issues and that it is resolved. Others may be having similar issues but for other reasons.


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## beebad (Mar 28, 2019)

JWPalmer said:


> For clarification, oxalic acid sublimates at around 157 degrees C. The bowl is heated to 230 degrees to allow for the immediate and rapid sublimation of the entire contents. Water boils at 100 degrees C and the amount of heat (calories or joules) necessary to cause water to boil is considerable relative to other substances. The more water that is present, the faster the bowl, and the tube which has very little mass, cools to below the OA's sublimation temperature. Once the tube cools to below 157, the OA forms back into a solid. Contact with 1-1/2" of wood, or any wet wood, both of which act as a heat sink, would cause the tube to cool even faster.
> 
> Beebad, I am glad you figured out what was causing your issues and that it is resolved. Others may be having similar issues but for other reasons.


Clarification or no, I just don't see how the negligible amount of water could affect this process....I have done about 60 OAV this fall, and moisture has not been an issue...Even if the 2g of oxalic was caked, the heat would drive off the moisture and surely, if it were OA MUD you had in the vessel, (The temp drops a little anyway), the unit would heat >157C and wayyyy past 100C and the process would still proceed. We can continue in ad nauseum.

Besides, the vessel and the tube is pre-heated or pre-heating to 230C as high as 250c, in my experience. The tube, the wood and everything would have to be submerged IMO, to have an effect and even then I doubt this would have an effect as described......I even forget what the point of all this is. That little bit of water content that may be in 2g of OA will resists boiling away keeping the OA from reaching 157c and becoming somehow dangerous? I just don't agree with any of that and that is ok...right?


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