Vapouriser

Thanks everyone it worked perfectly well when plugged into the car lighter socket ,so I think ,to be on the safe side I will use a 12v battery.

Stephen

Thanks to wessexmario, got the "Aluminium enclosed 12V 80W PTC Heater/Heating Plate ~175℃ Max Temperature" from a popular online auction site - £7. To give it a try and seems to work well. Used tin foil to form a dish like shape to hold OA. had it working several times all seems ok.

What sort of heat-up and cool-down times were involved ?
LJ

wessexmario said:

I've been looking at the amazing range of prices for what is essentially the same item...

A well known online bee supplies shop sell a varrox vaporiser - £140
I bought a "Aluminium enclosed 12V 80W PTC Heater/Heating Plate ~175℃ Max Temperature" from a popular online auction site - £7

What's the difference? Well, the expensive item has a nice label on it, and doesn't come supplied with a long lead and battery clips (I had some in the shed, but could have bought new for around a fiver)

I just screwed the PTC plate to a small piece of scrap plywood to stabilise it (the cable I used, however I lay it out, likes to keep twisting) I tested mine outside in the cold this afternoon, and it worked a treat, so now I'm all set up for treating them after christmas.

I have a digital thermometer on a multi-meter, so watched the temperature of the PTC plate during the test.
The plate was inside an empty super (to protect it from the cold breeze, and replicate it being in a hive)
It took 3 minutes to get up to 178C, and then held that temperature +/-2C for the 4 minutes I had the battery connected.

Click to expand...

Any chance of a photo of your final set-up. The idea of screwing the PTC plate to a piece of plywood gave me thoughts of how did he do that? - through the PTC or strapped? What will hold the OA crystals in place while you manoeuvre it?
Have you treated yet and if so, how did it go?

CVB

Just poking around in connexion with a thread on foundation, I found this. Not much more thatn a varrox, but more disturbance.

http://www.alfranseder.de/Oxamat-Oxalic-acid-evaporation-machine.html

Hi all,
In the craze that is developing for vapping, I am a bit concerned for the humans doing it. If I have understood it correctly, then the bees are covered in very fine crystal dust. Effective treatment, and they don't eat it because there is no sugar involved. However, what becomes of all the dust in the hive? Apparently, it condenses in the hive because it is hygroscopic. Some areas of the hive one would hope are warm and dry? I am concerned about residue in the hives which one could breath in at a later inspection. Also, even if the crystals condensate and the water evaporates in the summer heat will there not be residue in the hive? Clarification from the experts on the forum would be nice. Thank you and Happy New Year.

beeno said:

Hi all,
In the craze that is developing for vapping, I am a bit concerned for the humans doing it. If I have understood it correctly, then the bees are covered in very fine crystal dust. Effective treatment, and they don't eat it because there is no sugar involved. However, what becomes of all the dust in the hive? Apparently, it condenses in the hive because it is hygroscopic. Some areas of the hive one would hope are warm and dry? I am concerned about residue in the hives which one could breath in at a later inspection. Also, even if the crystals condensate and the water evaporates in the summer heat will there not be residue in the hive? Clarification from the experts on the forum would be nice. Thank you and Happy New Year.

Click to expand...

It's a really good question, and I've asked about the fate of OA in the hive before, with no result. No luck searching either although Google shows that OA does not decompose readily. Guessing, I imagine some of it must end up in honey as it is uncapped or, in spring, nectar, and get consumed in weaker concentrations than prevail in OA syrup (and thus pretty harmlessly). But that is a guess. What (I think, or it would be a major problem) we know is that it is not detectable above background in honey the following season.

I found this

http://www.ema.europa.eu/docs/en_GB...sidue_Limits_-_Report/2009/11/WC500015217.pdf

Oxalic acid is a natural constituent of honey and is found normally in the range of 1 mg/kg to 800 mg/kg, depending on the botanical source of the honey. A large number of publications was provided concerning possible excess residues of oxalic acid in honey as a result of treatment with beehives with the substance. Investigations were mainly conducted as field trials and were not performed under GLP conditions. Nevertheless the investigations covered a realistic spectrum of treatment conditions and gave a useful overview of the possible residues of oxalic acid in honey (sum of free acid plus oxalates) as they would occur under conditions of good bee keeping practice, using recommended oxalic acid application methods like spraying, trickling and evaporation. In none of the investigations was a signifiernt increase of natural oxalic acid in honey observed. Concentrations of oxalic acid in honey measured after recommended and off-label treatment conditions were in the range of 5 to 289 mg/kg which is well within the natural variability.

TryingToLetThemBee said:

Just poking around in connexion with a thread on foundation, I found this. Not much more thatn a varrox, but more disturbance.

http://www.alfranseder.de/Oxamat-Oxalic-acid-evaporation-machine.html

Click to expand...

Ingenious but cumbersome I fear - looks like something you could knock up from a few bits of drainage pipe and a glow plug - only the moulded covers would be difficult but I'm not really sold on the need for 'circulation' of the submlimating OA ...

I did. however, like his foundation mould ... particularly the silicon 'overflow' taking the excess wax straight back into the steamer ... and the ease with which the overflow chute could be cleaned - neat idea.

beeno said:

Hi all,
In the craze that is developing for vapping, I am a bit concerned for the humans doing it. If I have understood it correctly, then the bees are covered in very fine crystal dust. Effective treatment, and they don't eat it because there is no sugar involved. However, what becomes of all the dust in the hive? Apparently, it condenses in the hive because it is hygroscopic. Some areas of the hive one would hope are warm and dry? I am concerned about residue in the hives which one could breath in at a later inspection. Also, even if the crystals condensate and the water evaporates in the summer heat will there not be residue in the hive? Clarification from the experts on the forum would be nice. Thank you and Happy New Year.

Click to expand...

You may be confusing processes. The oxalic you buy is dihydrate, that's the stable crystal structure. It's not hygroscopic in that it doesn't absorb more water from the atmosphere (see the linked paper). The effective chemical is the crystals on the bee and mite surface. A certain proportion of the dose will settle and fall through the mesh, I'd think this would actually be a substantial proportion eventually as the bees clean themselves and any comb they find dusted with crystals. The initial anhydrous crystals will rehydrate to the dihydrate form, but after that should be a stable crystal and readily fall when disturbd by bees.

There will be some crystals which dissolve in condensed water within the hive, or in any open cells of honey. The levels detected after treatment suggest that readily disappears from the hive, whether that's dripping out or metabolised by the bees isn't clear but it's not there when the honey is later tested. My guess is that the proportion that falls out almost immediately is quite high. See the residue on the tray if you try sublimating from below the mesh. So sublimating leaves a much smaller dose still in the hive or in the bees than dribbling after, say, 24 hours. If anyone is aware of research I'd like to see it, much of the above is just observation. Practically I can't think of a way of testing it definitively without being rather destructive, but collecting the fallen proportion should be possible and a partial answer.

Erichalfbee said:

I found this

http://www.ema.europa.eu/docs/en_GB...sidue_Limits_-_Report/2009/11/WC500015217.pdf

Concentrations of oxalic acid in honey measured after recommended and off-label treatment conditions were in the range of 5 to 289 mg/kg which is well within the natural variability.

Click to expand...

So you can bury several OA treatments in the honey of even a small hive and not taste it. Further confirmation here, especially 4.5.2. https://hal.archives-ouvertes.fr/file/index/docid/891665/filename/hal-00891665.pdf . The honey taste will be changed only if about 400 mg/kg of oxalic acid is added to blossom honey or if 900mg/kg is added to honeydew honey (Bogdanov et al., 1999a).

289mg/kg, let alone 400mg/kg sound like a LOT.

FA might not be so easy: it obviously has a more acid taste, which makes sense. I know what FA tastes like, and I know what battery acid tastes like: am going to sample some of the pre-mixed syrup I no longer use to compare OA.

<ADD>YMMV and do not try this at home but according to one man's taste buds, "6%"* Enolapi OA/ 30% sucrose mix takes like - ahem - stomach acid (I have just had norovirus) with a similar feeling on the teeth. "0.6%" tastes like lemonade and "0.06%" would get hidden in other flavours. That is about* 600mg/kg, so I confirm the above figures to my own satisfaction. I got the tastes out of my mouth with a carrot, natch.</ADD>

* Do NOT go there please.

Hi alanf,
Much obliged for your thorough explanation. I shall not participate in any Vapping, but shall not worry about inspections at a later date.

beeno said:

However, what becomes of all the dust in the hive?

Click to expand...

the results are going to be very different depending on if the hive has an OMF.

With an OMF I would expect the majority of the residue to fall out of the hive.

charlievictorbravo said:

Any chance of a photo of your final set-up. The idea of screwing the PTC plate to a piece of plywood gave me thoughts of how did he do that? - through the PTC or strapped? What will hold the OA crystals in place while you manoeuvre it?
Have you treated yet and if so, how did it go?
CVB

Click to expand...

have a photo attached...
I have used two screws to mount the PTC to a piece of wood, with a couple of washers to space the PTC from the wood, as when I used it the first time it was clamped directly to the wood and charred it. There's a aluminium plate under the PTC, so in the photo it looks twice the size it actually is.
The mains wire is incidental, this is strictly a 12v setup, I just happened to have a bit of heat resistant immersion heater cable so I thought it'd be appropriate with the hot plate.

The PTC is held by overlapping the screw heads and a pair of washers at each end of the plate to keep it off the wood, I thought I'd just do a quick and dirty setup this time, and when I know it works (it does, and very well) I'll make a better clamp and oxalic holder for it, but even as it is, I found it no bother to use.
My hives are sat on a couple of fence posts laying across two piles of breeze blocks, so the blocks provided an easy surface to put the vaporiser on just under the OMF. I screened off the opening with a piece of wood and it worked a treat. As I mentioned in the other thread, I cracked open the top cover a millimetre just to give the natural convection a kick start, that worked quite well, I found that because of the way the wind was blowing, using a different side of the top gave quite a different amount of flow through the hive. There was more 'pull' through the hive with the opening on the downwind (low pressure) side.

wessexmario said:

have a photo attached...
I have used two screws to mount the PTC to a piece of wood, with a couple of washers to space the PTC from the wood, as when I used it the first time it was clamped directly to the wood and charred it. There's a aluminium plate under the PTC, so in the photo it looks twice the size it actually is.
The mains wire is incidental, this is strictly a 12v setup, I just happened to have a bit of heat resistant immersion heater cable so I thought it'd be appropriate with the hot plate.

The PTC is held by overlapping the screw heads and a pair of washers at each end of the plate to keep it off the wood, I thought I'd just do a quick and dirty setup this time, and when I know it works (it does, and very well) I'll make a better clamp and oxalic holder for it, but even as it is, I found it no bother to use.

Click to expand...

Thanks for that wessexmario. Very informative.

I have underfloor entrances so I would have to introduce the Vaporiser from the rear. I'm thinking I'll attach it to a flexible sheet of aluminium that will fit where the monitoring board sits, hopefully forming a good enough seal that holds in the vapour with a bit of help from some foam rubber. Above the Vaporiser, I'll attach a small but substantial, i.e. quite thick, tray to take the OA crystals. The only concern I have is that the OA vapour will have to pass through the stainless steel OMF and there may be some loss of OA due to condensation of the vapour on the cold steel mesh. Has anybody experienced this?

CVB

I haven't actually looked inside the hive since doing the first two applications. (trying to be a good winter beek) I'm planning to have a peek inside when I do the third application this week though, as I want to know how many seams of bees I have in each hive at this time of the year. (otherwise the drip advocates will be one up on their hive intelligence!)

Good point about vapour condensation on the OMF, I didn't notice much residue on the breeze blocks, but it was dark the last time. Losing a bit of vapour because of the OMF could easily be overcome by simply applying it for a little longer.

My concern was more that the hot acid might not be so good for the OMF,
so a coating on the mesh (zinc/plastic/paint/?) might be needed if the acid attack proves too aggressive.