Gasvap Modifications

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pargyle 

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If the torch reaches 200c then it is sublimating as formic acid.
Well ... yes and no. In order for formic acid to form from OA it really needs to be in an oxygen limited environment .. ideally in a sealed vessel. The Gasvap has enough air within it and as it's not a pressure vessel, in the real sense of the word, it would be almost impossible for this to happen - particularly with the small amount of OA you are using. The bowl would have to be heated well in excess of 200 degrees in order to cause instantaneous formation of formic acid and by this time the device would be glowing red ... with temperatures below that the OA is going to sublimate as OA first.

With an open pan type sublimator it would be almost impossible under any normal circumstances to create formic acid.
 

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Fair play Phil, your mods to the device makes this the easiest method to use for OAV. Big thumbs up!!
 

pargyle 

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Fair play Phil, your mods to the device makes this the easiest method to use for OAV. Big thumbs up!!
I have one more mod in mind but it's not to the Gasvap ...

I reckon it would be far easier if the OA (Apibioxal of course) were in 2.25gm tablet form and each tablet was encapsulated in those blister packs that you get medicine tablets in these days ... so, whilst it is not a problem measuring out the OA, just think how much easier it would be if all you had to do at the apiary was pop a tablet out of the blister pack, lift the cap off the Gasvap and drop a tablet into the bowl - no need for tipping the thing upside down and messsing about with powder ...

I see Park beekeeping are still advertising 1.5gm OA tablets - looks like they are made in Italy - but any mention of what they are intended for has been removed from the advert. Sheffield Beekeepers also list the same product.



Making tablets is not difficult - it's just a matter of pressure in a former .. sometimes a binder is needed - cold seal blister packs are available ... so, watch this space.
 

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I have one more mod in mind but it's not to the Gasvap ...

I reckon it would be far easier if the OA (Apibioxal of course) were in 2.25gm tablet form and each tablet was encapsulated in those blister packs that you get medicine tablets in these days ... so, whilst it is not a problem measuring out the OA, just think how much easier it would be if all you had to do at the apiary was pop a tablet out of the blister pack, lift the cap off the Gasvap and drop a tablet into the bowl - no need for tipping the thing upside down and messsing about with powder ...

I see Park beekeeping are still advertising 1.5gm OA tablets - looks like they are made in Italy - but any mention of what they are intended for has been removed from the advert. Sheffield Beekeepers also list the same product.



Making tablets is not difficult - it's just a matter of pressure in a former .. sometimes a binder is needed - cold seal blister packs are available ... so, watch this space.
Philip I have investigated tablet makers on Amazon after having used up my stock from Park. If you are in the mood to make one put me on the customer list.
 

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Philip I have investigated tablet makers on Amazon after having used up my stock from Park. If you are in the mood to make one put me on the customer list.
I’ve seen them in use for a few years , they are convenient! Two tabs per 14x12 however , whilst the gas- vap can remain upright , the cap needs dropping on to contain the vapour. , remember you will be keeping it up to temp !
 

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I’ve seen them in use for a few years , they are convenient! Two tabs per 14x12 however , whilst the gas- vap can remain upright , the cap needs dropping on to contain the vapour. , remember you will be keeping it up to temp !
I was thinking more for the sublimox
 

pargyle 

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Philip I have investigated tablet makers on Amazon after having used up my stock from Park. If you are in the mood to make one put me on the customer list.
I've been investigating it for about a week now .. I have the means to provide the mechanical pressure and I've ordered a tablet former but I think it will be too big for OA tablets so it will probably need some engineering ... I'll let you know how I get on.
 

pargyle 

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I’ve seen them in use for a few years , they are convenient! Two tabs per 14x12 however , whilst the gas- vap can remain upright , the cap needs dropping on to contain the vapour. , remember you will be keeping it up to temp !
Yes... bit of experimentation required here ...
 

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Well ... yes and no. In order for formic acid to form from OA it really needs to be in an oxygen limited environment .. ideally in a sealed vessel. The Gasvap has enough air within it and as it's not a pressure vessel, in the real sense of the word, it would be almost impossible for this to happen - particularly with the small amount of OA you are using. The bowl would have to be heated well in excess of 200 degrees in order to cause instantaneous formation of formic acid and by this time the device would be glowing red ... with temperatures below that the OA is going to sublimate as OA first.

With an open pan type sublimator it would be almost impossible under any normal circumstances to create formic acid.
I have not heard that before and would be interested to see your source.

This from Encylopedia Brittania:
"The hydrated acid crystallizes in prisms which effloresce in air, and are readily soluble in water. It loses its water of crystallization at l00 C., and begins to sublime at about 150-160° C., whilst on heating to a still higher temperature it partially decomposes into carbon dioxide and formic acid, or into carbon dioxide, carbon monoxide and water; the latter decomposition being also brought about by heating oxalic acid with concentrated sulphuric acid."

I believe that decomposition into formic acid will only occur if the crucible is heated to a high enough temperature before adding the crystals. If the crystals are added at 160C or lower and then heated further, the latent heat absorbed will keep the temperature at 160C in the same way that boiling water cannot exceed 100C. The decomposition does not need extra oxygen.
 

pargyle 

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I have not heard that before and would be interested to see your source.

This from Encylopedia Brittania:
"The hydrated acid crystallizes in prisms which effloresce in air, and are readily soluble in water. It loses its water of crystallization at l00 C., and begins to sublime at about 150-160° C., whilst on heating to a still higher temperature it partially decomposes into carbon dioxide and formic acid, or into carbon dioxide, carbon monoxide and water; the latter decomposition being also brought about by heating oxalic acid with concentrated sulphuric acid."

I believe that decomposition into formic acid will only occur if the crucible is heated to a high enough temperature before adding the crystals. If the crystals are added at 160C or lower and then heated further, the latent heat absorbed will keep the temperature at 160C in the same way that boiling water cannot exceed 100C. The decomposition does not need extra oxygen.
I'll have to look it up again ... I investigated it some time ago when issue was raised previously on the forum and my comments were from memory. My understanding of the chemistry is that it will only form Formic acid if there are no additional oxygen molecules present - I'm happy to be corrected, I will look up my original source. However, in terms of beekeeping and OA sublimation it's a bit esoteric as it would be almost impossible to create the conditions for the formation of Formic acid with any of the conventional equipment currently on offer.

It's quite a complicated process if it is to be reliably formulated ... here's some bedtime reading for a starter ...

 

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Yes it is. As I stated above, overheating OA will partially decompose it into formic acid and CO2 - however even that is undesirable.

For practical purposes the best technique is to pre-heat to <160c, add the crystals, then turn up the heat. Turn the heat down/off between hives. The same technique should be used witha Varrox-type heater, cooling the pan in water after each application.
You can gauge the correct starting temperature by adding some crystals when warming up the GasVap. When they start to sublimate you are there! The Tempilstiks look useful too but I have not used one.
 

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I just went and checked, mine is a Mk1 model with shield soldered to body, I thought I couldn't remember seeing a screw.
Oh well, back to thick gloves if I use it again.
 

victor meldrew 

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I just went and checked, mine is a Mk1 model with shield soldered to body, I thought I couldn't remember seeing a screw.
Oh well, back to thick gloves if I use it again.
It will be brazed rather than soldered!
 

Etton 

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I have found when using the extension pipe to my gasvap the OA often condenses in the tube and blocking it.
The reason being the tube is taking a lot longer to get up to temperature, so I use my second burner (I have a spare) to heat just tube itself and that solves the problem most of the time.
 

victor meldrew 

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I have found when using the extension pipe to my gasvap the OA often condenses in the tube and blocking it.
The reason being the tube is taking a lot longer to get up to temperature, so I use my second burner (I have a spare) to heat just tube itself and that solves the problem most of the time.
Yet copper has a high conduction rate ! This means it will heat up very rapidly but also cool rapidly. The further from the the heat source the quicker !
 

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