I made a starter last night. Mixed my DME & water then added it to the flask. I then put my flask on my little camping stove (gas flame) & walked out of the room.
A minute later I heard a crack & upon inspection saw a big smile like crack running right across the bottom. What did I do wrong?
That sucks dude, they are made of thick borosilicate glass and should be well able to deal with a gas stove.
I have contacted the manufacturer directly about it and I will get back to you here with their reply.
Quote from: shiny on April 19, 2013, 10:18:18 AM
That sucks dude, they are made of thick borosilicate glass and should be well able to deal with a gas stove.
I have contacted the manufacturer directly about it and I will get back to you here with their reply.
Thats what I figured. It was its maiden voyage too :'( Thanks a million for mailing them. No worries if nothing comes of it.
Oh it was the maiden voyage too! I'm going to go after them for a replacement in that case. You haven't dumped it have you?
Quote from: shiny on April 19, 2013, 10:22:19 AM
Oh it was the maiden voyage too! I'm going to go after them for a replacement in that case. You haven't dumped it have you?
No I still have it. Do you want me to send it up to you or take pics? Appreciate the help.
Hold onto it for now. They have forwarded my query onto tech support in the UK which can take up to 3 days. If they want it back I'll just get you to post it to them directly.
Fair play. I wasnt expecting this at all. I was guessing it was something I did wrong.
Borosilicate should NOT crack under heat like this... It's not a good sign that it DID crack...
Adam
Yeah it cant be anything else than a manufacturing defect.
I was talking to my auld lad over the weekend who has been boiling liquid in them for as long as he can remember in his lab and he has never seen one crack or break over a flame.
Is your auld lad the guy from Breaking Bad :P
Quote from: DEMPSEY on April 23, 2013, 11:57:29 AM
Is your auld lad the guy from Breaking Bad :P
::)
Just to update, I haven't waited for their support guys to get back to me, I have asked them to just replace it.
On a domestic gas cooker a single concentrated flame jet CAN locally overheat the flask.
If you use a naked gas jet/bunsen burner then you need to diffuse the heat.
This is the old wire gauze square thing we used in school labs (just nowadays they won' have the asbestoss centre pad - coughs and weezes loudly :()
How do I know this? Coz I cracked an expensive, ground glass jointed thick walled Erlenmyer on a gas cooker the day after I bought it!!
Never use thick walled borosilicate glass ware on naked gas jets!
Quote from: Will_D on April 23, 2013, 11:36:02 PM
Never use thick walled borosilicate glass ware on naked gas jets!
Is there are reference to this in a specification? From searching so far I see a mixed bag as to what is acceptable and what is not...
Shane,
I really think its down to laboratory practical experience.
Thick walled Erlemyers are used for vacuum filtration ONLY and as the conical section and flat bottom are not good under a vacuum they beef up the thickness!
Likewise a thin walled flat bottom flask should not be used under vacuum.
Localised overheating coupled with a "minor" flaw and poor fluid distribution on the wet side will cause a problem.
Remember you can boil water in a paper container but thick cardboard will probably burn through!!
However I would still class this as faulty!
(Purpose of this post is just to give the heads up to others who may not be lab. experienced)
Yeah that was the one question my auld lad asked, was the outside of the flask wet when he started heating it. Personally I have heated my 3L conical with the outside wet but that was on an electrical cooker. Overall I have treated it like shite without any problems, such as heating when wet, dunking into ice water when boiling hot etc...
Will, you have one of the 3L flasks yourself so you can see how thick the glass is, IMO they are absolute tanks of things. The glass is very thick. I don't know whether Tom was using his flask with a vacuum or not, I would guess not as most of us are just boiling in the flasks at most...
If they don't replace it, I am pretty much going to suggest that they are putting people at risk by selling defective products to customers. If that flask had of ruptured over Toms arm while boiling that would have resulted in some serious burns which is fairly unacceptable to me. >:(
Ok I have heard back from the manufacturer. This was their response:
Quote
Any Erlenmeyer flask of any brand would be subject to thermal shock in the circumstances described by the customer and would very likely devlop cracks or even shatter. Direct flame should never be applied to containerware such as beakers and flasks. A diffuser of some form usally resting upon some form of support such as a tripod stand should be used.
But as a gesture of good will they (Fisher Scientific) have offered to send out 2 flasks free of charge! :o
I should have them by Monday so give me a shout on how to organise getting a replacement out to you.
I didnt use a vacuum & the flask was dry going on the flame. Ive seen loads of videos online of people using theirs on their stove so I dont see why i should have used mine any differently.
Surely these are tested to way higher temperatures than the actual intended usage temp to ensure it doesnt fail & injure the user.
Cheers for the legwork then & now Shiny. Much appreciated :) Il be in Dublin the weekend of 10th May so if you're around I could meet you somewhere convenient for yourself.
Yeah I have found the same when researching the proper usage of these items in terms of the amount of people using them on gas cookers. I suppose its just something to be careful about (for the other flask owners too) in the future as I don't think I will be able to get any further replacements.
No flame at all then or bunsen with diffuser?
Yeah that's what I'm taking from it. A naked flame seems to require some sort of diffuser whether that be the wire gauze type or one of these:
(http://i.ebayimg.com/t/SIMMER-RING-WOODEN-HANDLE-HEAT-DIFFUSER-GAS-OR-ELECTRIC-HOBS-OR-COOKERS-/00/s/MTYwMFgxMTI3/$%28KGrHqV,!qUE-Z!4mcLQBPq7%29r3p3w~~60_35.JPG)
I've been using my flask on the gas jets of my burner since I got it over a year ago from brouwland. Don't know what you guys have but mine doesn't feel very thick walled. I thought these were bulletproof!!! Where can I get a diffuser? Need one for my paella pan anyway
I have seen plenty of people using them on naked flames without issue but all I can do is pass on the information that was given by the manufacturers. If it happens again I don't think I will be able to go back to them for further replacements.
Just search for 'heat diffuser' on ebay and they are very cheap.
Its called a "wire gauze" Its just a small square of wire mesh (Copper or SS) that diffuses the heat.
As half of you here must have done some sort of science in secondary school, you never boiled a 50 ml Pyrex beaker on a Tripod support over a naked Bunsen burner as the small beakers just fell though the triangular hole!
Use a wire mesh - its standard lab pratice