Sciencemadness Discussion Board

Where to buy a cheap & good RBF newware 29-32 or + 10 L EU

pneumatician - 17-5-2021 at 17:01

Hi, where I can buy a good and cheap 10 liters round bottom flask with 29/32 joint or bigger in Europe?

I purchased a good Simax with 60/46 joint at this guy. Have a lot and I say: well in a time I buy another, but in some days the "lot" is 0 :-(

I pay 80 € plus 20€ shipping with a lot of others flask...

No, I can't want a China flask from ebay, this is my last option...

https://www.laboreinkauf.de/

Texium - 17-5-2021 at 17:39

What on earth do you need multiple 10 L flasks for?

pneumatician - 17-5-2021 at 18:20

Water, wine... distillation... read my post about the shit in my reactor, I don't want to use this "dirty" flask for plant's oils and etc. So I need 2, one for water only.

it helps a lot, too, that a moment ago has just broken one, RIP :-)

this shit in the flask is fluorine added to water for "tooth health"???

in reality, how many times a flask can be used at around 100ºC? before the joint break? by termal stress, force joining pieces... this data never is said publicly, perhaps because they already count on people breaking it first??

Fery - 17-5-2021 at 22:08

Recently I distilled using stainless steel apparatus (20 L pot) and only final column distillation using glass (1 m tall Hempel 30 mm inner diameter packed with Raschig rings, 4 L RBF, variable reflux ratio head).
Simax 4 L is with 45/40 ground glass joints so it required reduction adapter to connect to 29/32 joint column. Chemland produces upto 6 L RBF with still 29/32 joints and 10 L and 20 L are only with 45/40
https://sklep-chemland.pl/en/szklo-laboratoryjne/szklo-z-ele...
of course they produce also smaller volume RBF with 45/40 like 0,5 L, 1 L, 2 L, 4 L, 6 L but the biggest volume with still 29/32 to avoid using reduction adapter is Chemland brand 6 L (in such tall apparatus every saved cm counts especially if you are close to the ceiling of your lab, I had to put the apparatus to the ground as it was too tall).

[Edited on 18-5-2021 by Fery]

Fyndium - 17-5-2021 at 23:25

Indeed if materials are compatible you could get away with stainless steel.

And if you really wanna push it, some reactions can be run in the good old 1$ plastic bucket.

After that, and the Chinese, Chemland is likely the best bet. Germans will sell high quality flasks, but the price is also high. For 10L 3N will command 400€ price tag.

Personally, I would not purchase other than 3 or 4 neck flasks, because the mere overhead always takes one slot, and also reflux/distillation, thermoprobe and addition funnels may be needed. IR thermometers may be a bit difficult to read through glassware at some instances, I've experienced.
Quote: Originally posted by Texium  
What on earth do you need multiple 10 L flasks for?


A rare instance out of production, but at least herbal extractions and alcohol distillations warrant large vessels. I find it handy having at least one larger flask in case of some voluminous reactions, collection vessel for filtrates or washings or simply for purifying a batch of solvents collected over time. I have 50L boiler for alcohol distillation with 1200mm bokakob column, and it does not produce more than couple of liters of prime quality vodka per batch of grain wash that has around 10% ABV. Considering the time it takes to stip and frac it, running it in 10L scale would take 40-hour work week to complete the whole batch.

pneumatician - 18-5-2021 at 06:00

Quote: Originally posted by Fyndium  
I

A rare instance out of production, but at least herbal extractions and alcohol distillations warrant large vessels. I find it handy having at least one larger flask in case of some voluminous reactions, collection vessel for filtrates or washings or simply for purifying a batch of solvents collected over time. I have 50L boiler for alcohol distillation with 1200mm bokakob column, and it does not produce more than couple of liters of prime quality vodka per batch of grain wash that has around 10% ABV. Considering the time it takes to stip and frac it, running it in 10L scale would take 40-hour work week to complete the whole batch.


this is the reason, 10L flask in practice is a 5L liters flask, so if you need 1-2 liters of pure alcohol... is crazy to obtain it in a 2L flask from wine of 15º

I not use all in a time, is a question of matters ready for use, if every time you need a bit of alcohol is necessary to distil wine 4 times is not practique... is like if you need some iron and need to go to the mine and get some ore...

https://www.youtube.com/watch?v=QxoW3bpU4BQ

many idiots put a handfull of Melissa in a 250 ml flask and after distillation blame to hell: for what reason I can't get 1 liter of Melissa essential oil??? :-D

the reactors in the video are of 50 or 100L and cost around 6000€ for unit, the reactor only, uppppss!!!

Fyndium - 18-5-2021 at 06:32

Yes indeed, effective useful volume is 50-70% of the nominal volume of the flask. Hence you won't be able to run that big of a reactions in seemingly large flasks. Some specific instances allow using up to 80 or even 90% of the flask volume, when the reaction is not (too) exothermic or does not need to be heated too much and two separate reactions could be fitted into one batch this way. I've done it, many times actually.

It is common practice to distill large amounts of potable alcohol at once. It is common to distill up to 10-20 liters of pure azeotropic ethanol, and then put away the equipment and use the product for the coming year or so. For me, these have been extremely useful for party punches and other drinks where large amount of heavily taxed alcohol would be needed otherwise. The capital costs of a good still can cover a dozen liters of taxed alcohol, but after that it pretty much pays itself off after one run.

A line will be drawn between experimenting, useful homebrewing of all kinds of stuff, and commercial production. For experimenters, it is beneficial to use minimal size equipment to minimize reaction costs and overall mess. For homebrewing of all kinds of alcohols, herbals and other stuff, balance between capacity and cost must be considered. For production, well, you can as well just stack rows of 10L 3N RBF:s instead of one huge 50L vessel. In commercial plants, we quickly escalate into 10 or 50 tons, not liters.

But I still find it somewhat pitiful when someone proudly says they distilled few dL of azeotropic ethanol for solvent use during 12-hour fractionating run. I might not need 10 liters of solvent at once, but the little time I have for my lab, I ain't using it just to distill all kinds of bulk solvents for several small batches in 1L flask, I rather get that fiver or tenner and distill it once for good. Even then you find that simple distillation and fractionating of good solvent easily takes a whole day, but once you've done it, you've got good solvent for the rest of the year. Same like homebrewing.

Chinese actually sell those huge flasks for quite a bargain. You don't need to pay more than 500$ for 50L flask, so the bigger, the cheaper, for that matter, but handling, heating and cooling, reflux and distillation and stirring will also get into totally another level. It is basically frame-supported stationary mounted reactor, which needs good overhead stirrer, special large-scale condenser and either a large heating mantle or a heating-cooling bath that itself is a size of an oil drum. And if you get that into a runaway reaction, you just don't dunk it into cold water or pour ice water on it - you probably just have to run, fast, and hope it won't take down the entire building when it really gets out of control. And the batch reagents just cost you 2000$ alone to charge it.