A Non-Inverting Band-Heater Vapouriser
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  1. #1
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    Default A Non-Inverting Band-Heater Vapouriser

    Well - Johno has pretty-much cracked a DIY version of the Sublimox/ProVap design, and it's very hard to imagine this being further improved upon.

    However, I thought there might be some mileage in developing a Non-Inverting Band-Heater Vapouriser which could sit on top of the Crown Board (inner cover) - perhaps even with the operator just pressing a button and walking away.

    I can see two possible advantages with such a press-button non-inverting design: firstly, there would no longer be any need to get 'up close and personal' with any Oxalic Acid dust (not that I've personally had any problems in this regard with Johno's design) - for this type of applicator could be operated remotely - from 10, 20 feet away - or even from within the next field if you're really paranoid; and secondly there would be no need to stand there like a lemon holding the applicator while it performs it's magic - indeed, with a timer added it would then be possible to automate the process such that it does indeed simply become a case of 'pressing a button, and walking away'.

    There's a third advantage for myself: at 6'4" I invariably need to stoop when using a hand-held inverting band-heater vapouriser - depending on the hive height, of course - and I'd really like to eliminate that.

    There is, of course, one major disadvantage of the 'cold > hot > back to cold again' sequence of the Varrox protocol in that it's very much slower than that of the inverting band-heater design. On initial testing I found this to be somewhere around 9 minutes from cold to cold - but as these non-inverting units promise to be insanely cheap to make - it could well become cost-effective for several units to be made and then operated at the same time (perhaps on the Master-Slave principle ?). But - for anyone interested in this approach, please DO be aware from the outset of this limitation.

    Johno has discovered that injecting OA dust at or near the top of the hive is preferable to dosing from the bottom - so for now I'm sticking with this principle - and the lower operating temperature of this design means that construction can be far less demanding for the DIY-er. Ok, enough chat ...


    Here's a sketch of the basic concept:



    The narrow-bore delivery tube has a ID of 4mm and extends upwards inside the can by 25mm (1 inch), and protrudes downwards until flush with the base-plate, which enables the assembly to then be slid into position over the feed-hole in the Crown Board (inner cover).
    The prototype 36mm OD brass 'reaction vessel' I'm using is fitted with a 150W Band-Heater - which will be replaced by 28mm copper fittings and a 120W Band-Heater providing this trial shows some promise. A standard (and therefore low cost) demi-john cork will fit perfectly into a 28mm fitting - but as a bung for this 36mm tube would cost as much as a PID controller (crazy, or what ?), I've made a simple weighted gravity closure thusly:



    So - onto the prototype build itself ...

    Bearing in mind that this is still very much at the experimental stage - here's the woodwork of the first prototype rig:



    I've fitted a heatshield to protect the controller, which is probably unnecessary, but rather safe than sorry ...

    And a pic of the 'reaction vessel' itself, which I've already posted:



    The joints of this vessel have been made with Lead (Melting Point 327C, 620F) NOT solder, using a bog-standard propane torch, and it has already been successfully soak-tested at 250C (480F). In use, the normal operating temperature of this assembly is not expected to exceed 200C (390F).
    Of course, brazing or silver-soldering is a far better technique to use should you have the necessary equipment.

    So here's a shot of the state of build as at this morning:



    The can is held firmly in position by a pair of s/s wires. A toggle switch has been fitted so that the controller will still act as an electronic thermometer whilst the reaction vessel is cooling (with the heater switched off), post vapourisation. The small shield over the connection block is to prevent accidental contact with the 220V present on those terminals.

    To the left of the assembly is the gravity closure already mentioned, together with a simple cover made from squashed copper tube which will prevent any dispensed Oxalic Acid from falling down the delivery tube - thusly:



    And finally, with the gravity closure in place:



    So - all that remains now is to wire the thing up and insert a K-type thermocouple in-between the bottom of the can and the rubber insulating washer below it. I'm sure that'll perform adequately for now, although I'll rig-up something more workman-like for the finished product (assuming that ever happens ... ).

    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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  3. #2
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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Quote Originally Posted by little_john View Post
    Johno has discovered that injecting OA dust at or near the top of the hive is preferable to dosing from the bottom - so for now I'm sticking with this principle
    Also found that the treatment is more effective from the top a few years ago, like your design LJ, only thing is it maybe better with a bend at the bottom of the vertical tube or raise it higher if using direct down through a crown board hole, use sublimox vaporizers here and the heat of the vapor straight from the nozzle is quite hot, hot enough to fry some bees and one could well be the queen if using a center feed hole, maybe your device will be cooler...just my thoughts on it.

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    Thumbs Up Re: A Non-Inverting Band-Heater Vapouriser

    That certainly opens up some different aspects. It would be so much easier to administer through the inner cover rather than humped up like a dog on a football using the hole in the bottom rear of the hive. The discharge tube out the bottom would be an easy construction. No handle needed.

    Using the plywood bottom would accommodate everything from a feed hole to a bee escape hole or even a small drilled hole if your inner cover had no openings. The flat gravity seals would be positive sealing and easy to create. Silicone sheet is readily available in kitchen section of department stores or made with tube of liquid hi temp silicone.

    Cycle time could be reduced if you did not wait till the bowl came entirely back to room temp. I found with the tray heaters that a temperature of approx 180 F. would allow dumping in a fresh charge without any fuming and quickly brought up to vaporization temp. With two such units leapfrogging I think they could be quite efficient.

    I am a thinking that I will be using those ideas to make one without temperature controls. I use Sil Phos for joining so will not have to worry about the temperature limitations of the lead base solders.
    Frank

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Quote Originally Posted by beekuk View Post
    [...] raise it higher if using direct down through a crown board hole, use sublimox vaporizers here and the heat of the vapor straight from the nozzle is quite hot, hot enough to fry some bees and one could well be the queen if using a center feed hole, maybe your device will be cooler...just my thoughts on it.
    Hi Pete - hope you had a good season.

    Very much appreciate your comments about the heat issue - to be honest, that's something I hadn't even considered and I'm not sure why ... maybe just because it's not an issue which features much with the Sublimox(?) - but as you rightly point out, in contrast I could be dosing more-or-less directly above the cluster. Point very much taken.

    What I'll do now is to test with a sheet of thin wax lying across the top bars (of an unoccupied hive, of course) and check it for heat damage. I'll then raise the whole assembly with shims of 10mm plywood until that damage disappears. I know that's hardly any guarantee, but right now I can't see another simple method of determining some kind of acceptable temperature. I don't think inserting a thermocouple into the exhaust stream would help much as I'll be looking for a fairly fast peak temperature event.
    Then, assuming that cures the problem, the copper fittings could be mounted on top of (say) a 2" wooden stand-off tower - or whatever height is considered necessary.

    Many thanks for that, Pete. Always good to get input from others.

    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Quote Originally Posted by crofter View Post
    I am a thinking that I will be using those ideas to make one without temperature controls. I use Sil Phos for joining so will not have to worry about the temperature limitations of the lead base solders.
    Hi Frank - yes, with that method of joining you could just time the operation a few times, add 15 seconds or so ... and I'm sure that would be good enough. It could even be automated with a $2 timer ex Ebay !
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Why have a plug on top of the crucible and force the vapor out the bottom? I am thinking of using an inverted glass bowl with weatherstrip around the edges, sealed over the opening in the inner cover. Let the vapor come out the top of the heated crucible (under the inverted bowl) and find its way down through the inner cover. Glass bowl because then I can see when the OA is all vaporized and turn off the heater.

    I bought a band heater to try this out, but over a month later when the heater arrived from Thailand, it was only 16 watts, not 300. Couldn't even bring a few cc's of water to boil in 5 minutes.

    ---Robin

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Lj the only thought I have with treating from the top going straight down is that the vapor jet will be going down and not creating a layer of vapor at the top, one would think if there was a horizontal baffle plate a little below the outlet pipe that it might get the vapor to disperse horizontally in a 360 degree plume. You would need to do tests with a plexiglass top to try to see where the vapor flows.
    Johno

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Quote Originally Posted by johno View Post
    Lj the only thought I have with treating from the top going straight down is that the vapor jet will be going down and not creating a layer of vapor at the top, one would think if there was a horizontal baffle plate a little below the outlet pipe that it might get the vapor to disperse horizontally in a 360 degree plume. You would need to do tests with a plexiglass top to try to see where the vapor flows.
    Johno
    I had the thought that a way to handle this concern as well as hitting hot on the bees, would be to baffle the bottom of the discharge tube so the vapor would be deflected out horizontally. If the inlet to that tube was open on the inside as in LJ's design, cleaning could be done from there. I have not found build up to be a problem though as long as discharge snout was hot and short.
    Frank

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    That’s thinking outside the box. You need to be sure to have clearance from the discharge to the frames. If the vapor hits directly on a close frame it will scorch it.

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    As a means of getting a good coverage of vapor at the top of the hives I am looking at building my migratory tops with a 3/16" slot at the back of the rim I put onto them to get correct bee space and then drilling a 1/4" hole through the back cleat to meet the 3/16" slot so that I can easily treat from the top. Also planning to build some Imrie type of shims to go above my queen excluders in spring. First of all that will give the bees more access to the honey supers and will also mean I can slip a boardin over the excluder and treat with OAV if I feel the need.
    Johno

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Update - today was the first warm day for quite a while: we saw 9-10C (48/50F) for several hours this afternoon, so I took the opportunity to do a mid-winter VOA treatment - a couple of weeks later than planned (due to British weather !).

    Two good points and two not-so-good points from this trial:

    Pressing a button (or in my case, flicking a switch) and 'walking away' is nothing short of brilliant - I'm completely sold on this idea. And the weighted gravity closure has also being working flawlessly.

    Negatives - the speed of treatment really is desperately slow, although this could always be improved by running multiple units simultaneously. But - there was one completely unforeseen HUGE negative ...

    When cracking-off the feeder-hole cover, in some (but not all) colonies bees immediately crowded into that area. Whether this is due to them occupying the space between the Crown Board (inner cover) and frames due to warmth issues, or whether this is a learned response due to my use of overhead jar feeders - where they frequently crowd into that area in anticipation of a feed whenever they sense my presence - couldn't say for sure. But whatever the underlying cause, that's a BIG problem as some of those bees would be getting the full blast, and from close range too. Not good. In practice I was able to somewhat overcome this by placing feeder jars over adjacent holes to entice them away from that hole, and then coming back to dose the hive later - but this was more sodding around which only served to interrupt the work flow.

    So, all-in-all an interesting 'first time out' - but I'm beginning to question the viability of this approach.
    LJ


    FWIW - this is a shot of a frame top bar afterwards, which is some 18mm (3/4") from the end of the delivery tube.



    As far as I can tell without a perspex top, the OA dust appears to spread reasonably well after striking a top bar.
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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Has this design gone any further? Tonight I tried to come up with an idea and this is where it is. I used a 1 1/4" copper cap and coupler brazed together. I drilled a hole into the copper cap and inserted a 5/16" ID piece of tubing with 3/4" of it sticking out. I brazed the end shut and drilled about 8 holes 1/16" diameter around the circumference of the tubing for 360 degree dispersion. I wrapped a band heater around the item and plugged it in. The results look good for further testing. I would say the vapor traveled aprox 10" in all directions under pressure. I had complete sublimation with no burning. Also since I didn't have any holes drilled straight down I think it may save a few bees during the treatment. My plan is to make a round cylinder perhaps a 3" piece of black pipe and center this vaporizer in the middle. Maybe attach a handle and treat it kind of like a coffee mug. Operation would be like the other vaporizers using a silicone plug to deliver the acid upon inverting the unit I think I can just open the outer cover and treat through the feeder hole of the inner cover without stirring up the bees. A few puffs of smoke would also clear the immediate area of any bees prior to insertion. I Will play around with the differend depths of the tubing also. I would like it to be just above the top of the frame so as to disperse the vapor in the bee space between the top of the frame and the bottom of the inner cover. It has much less pressure than the units that I made using a single 3/16" output tube.

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Good to hear of someone else 'stretching the envelope' ! I'd very much like to see a photo (or three) of what you describe - if that's possible - thanks.

    Has this design gone any further?
    Well, not this particular design - but I've since been thinking along parallel lines.

    As I see the Varroa situation, I reckon it's going to be around for a very long time yet - and is such an important issue that it warrants a significant hive design alteration (rather than trying to fit VOA applicators into existing equipment). So - what I'm currently thinking in terms of is: to have a modified hive base with sufficient internal height to accommodate the band-heater equivalent of the classic Varrox wand. Such an applicator could consist simply of a band-heater around a copper can, with some kind of insulating pad beneath it - and that's all. Such devices could be made very cheaply: rough costings suggest around $5-6 each, so running (say) 8 at a time would then make this a practical proposition, even if each VOA run should take 10 or even 15 minutes from 'cold to cold'.

    There is another potential application of such a device, which I had considered floating out to experienced members here in order to sound-out it's practicability ... and so this is as good an opportunity as any to do this.

    I want to say from the outset, that I'm not entirely convinced that heat treatment of Varroa is practicable - that heat treatment itself 'works' is not being doubted - but the very idea of around 3 hours for each treatment renders this (imo) a non-starter, that is, in contrast with existing methods of delivering VOA - even the slowest of those methods.

    But - suppose a simple band-heater device such as I've already described was allowed to dose the hive with VOA, and then be left in place in order to heat the brood area of the hive during the subsequent two or three hours ?
    A system controlling (say) 8 such band-heaters is very do-able (industrial temperature control being one of my areas of experience) especially when using modern electronic components. Assuming 250W per heater, then a supply of around 2KW (peak) would be required - which should not pose a problem if mains is available - but a 3KW generator would then be required in the field.

    Looking at this positively, after such a treatment a hive should be - for all intents and purposes - Varroa-free (or at least as 'Varroa-free' as any hive needs to be, as the prospect of re-infestation will always be present), with both 'phoretic' mites AND mites within cells having been dispatched - BUT - nevertheless, is treating even 8 hives every 3 hours a realistic prospect ? I'm really not sure about this, hence my request for opinions.

    The DIY cost of such a system ? Maybe $100-150. I really don't think cost is very much of an issue - it's more about the effective use of a beekeeper's time.
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Dux4life; your idea seems well thought out. I am thinking I want to be able to do top dosing so it is possible when my hives are deep in snow and the present rear bottom board is in accessible. I could use your idea as is without thinking I needed to personalize it!

    LJ; if you want fine and even control of temperature over a considerable area and volume, I think a larger and less intense heat source would be easier to manage than a band heater. That seems to have been an issue in the long duration comb heating mite killers. Not a big spread in temperatures between what is deadly for the mite and what is survivable by the bees and brood.
    Frank

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Quote Originally Posted by crofter View Post
    LJ; if you want fine and even control of temperature over a considerable area and volume, I think a larger and less intense heat source would be easier to manage than a band heater. That seems to have been an issue in the long duration comb heating mite killers. Not a big spread in temperatures between what is deadly for the mite and what is survivable by the bees and brood.
    Sure, I don't disagree with your comments. But - I was thinking of working with what's already available.
    The 'intensity' as you put it can very easily be dealt with by PWM control to reduce the effective wattage to whatever's required. It would be better to have a larger heater surface area though, I agree. With a concentrated heat source there may be a case to install a small fan to improve circulation - such details can be established during testing. FWIW, the best method of control for this kind of application would be Cascade Control.

    But - 8 hives in 3 hours - is this idea even worth developing ?
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Yes you can use a fan to help evenly spread the heat. I was not dissing the wattage of the band heater though it is likely more than enough to overcome heat loss. You can control wattage delivered as you mention but even heating throughout is greatly complicated by a small area source. If you try to do it with fans then you create a potential problem with dessication. I have seen some overheated colonies and the bees fan like heroes and would dearly like to get out and haul some water for evaporative cooling. You and they will be working at cross purposes.

    I am not big on anthropmorphising but I think that way of killing mites borders on cruelty to the bees. OAV cant be a picnic either! Lol! I dont like the exposure time requirements either for the whole hive heating method.
    Frank

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Hi Frank - I'm not completely 'sold' on the idea, either - it was just reading about the technique and observing that the heater being used was more-or-less the same kind of wattage and that the use of VOA was an additional requirement for an effective 'mite kill' - that I started thinking about putting the two events together, by using the same basic kit.

    I agree with you totally about the trauma aspect - especially when compared with my own bees' complete non-reaction to VOA. Always good to get the views of others.
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Last week I completed yet another sequence of treatments using 'the prototype' which was shown earlier in this thread - and personally I continue to be sold on this particular variation of the band-heater Vapouriser: open the feed hole, small puff of smoke to keep any inquisitive girls away, place the kit on top, load-up the OA, flick a switch and walk away ...

    There's no need for any PPE when using this method, and while the can is either heating-up or cooling down, the roof and feeder shell of the previously treated hive can be replaced, and those of the next hive can be removed in readiness.

    I've found that the vessel can be recharged with OA at 130 deg C (indicated) without any fumes being generated, and that vapourisation is completed by 170 deg C (indicated), so a complete cool-down isn't necessary - which speeds things up considerably.

    However, sometimes a small amount of waiting time does occur - which could very easily be eliminated by the use of two such vapourisers - indeed, they can be so cheap to make that using 2, 3 or even 4 at the same time becomes feasible.

    Anyway - the reason for this post is to share the modification I intend making during the coming winter period - which is to install an 'extended delivery tube', blanked-off at it's end, and with 4x 1.0mm (or thereabouts) holes drilled into it such that jets of VOA will be delivered into the beespace above the frame top-bars thusly:



    Although I figured this out independently, I've just realised that DUX4LIFE had already suggested this modification - or something very close to it. I think his idea of modelling the vapouriser on the shape of a 'Coffee Mug' is inspired, and of course there's no need for a temperature controller to be used as the temperature isn't being maintained - the principle here being very similar to that of the Varrox, and so some form of thermostat, or even a timer should be adequate.

    In practice the gravity closure has worked perfectly, is far cheaper to make than a silicone bung is to purchase, and I anticipate will have a long life-expectancy due to the lower temperatures involved.

    One negative is that this variation is slower than Johno's method - principally because of the need to expose the Crown Board (Inner Cover) rather than poke a nozzle through a hole in the back of each hive - and I'm finding it is this which limits the speed of use rather than the heating-up/cooling-down times. However, positive aspects are that it's a much cheaper build (at around $10, DIY) than an inverting band-heater unit, and also there's zero chance of encountering the OA aerosol due to the operator separation distance. (Not that I've ever seriously entertained such concerns when using the classic inverting method)

    So there you go - this might be a method worth considering for anyone with (say) up to 20 hives or so. I do have more than that number of colonies myself, but I intend working with 2 or 3 units.
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    Makes the exhaust tube much shorter, so should keep the interior of the tube cleaner from blockage.

    With a migratory top, one would only need to remove the pipe end cap and place unit over hole.

    Still 1 1/4 copper and an aluminum plug in bottom???

    250W, 1 1/4 inch inside diameter band heater, 110V band heater for North America???

    Silicone cone on under side may be nice to center top cap/plug.

    Similar action as Varrox and reduces need for mask.
    Zone 3b. If you always do what you always did, you'll always get what you always got!

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    Default Re: A Non-Inverting Band-Heater Vapouriser

    There's flexibility re: whatever materials are readily available in your own country - in Britain one solution for making the 'can' would be to use a 35mm copper end-feed end-cap, and attach that to a 35mm end-feed coupler with an inch or so of 35mm copper tubing. But as it happens I'm using some 36mm brass tubing which was a 'once-upon-a-time' Victorian greenhouse sprayer (bicycle pump type), and have enough tube to make 3 units. The current band heater is 35x45mm 150W and works very well, and so I think I'll be sticking with that size - although it is tempting to use 28mm copper fittings as this size is far more common here (and significantly cheaper), with a band heater to match. Most 30mm dia. band heaters tend to be 120W.

    There's basically only two components which cost any money - the can and the band-heater - the cost of everything else is only pennies.
    LJ
    A Heretics Guide to Beekeeping http://heretics-guide.atwebpages.com/

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