Sciencemadness Discussion Board
Not logged in [Login - Register]
Go To Bottom

Printable Version  
 Pages:  1  2
Author: Subject: Fire & Explosion risk vs. scale
LearnedAmateur
Hazard to Others
***




Posts: 174
Registered: 30-3-2017
Location: Somewhere in the UK
Member Is Offline

Mood: Free Radical

[*] posted on 13-1-2018 at 05:00


I assume this is common knowledge but I’ll add it anyway since it hasn’t been mentioned - never use water to extinguish a solvent fire. Dumping water onto an immiscible solvent will just cause it to float and keep burning, riding the water and going where it flows, and spraying with a hose will likely end in the fire becoming even more widespread. Not so much a problem with ethanol and such (mist setting), but kerosene, DCM, toluene etc. is the real issue. An even bigger danger is if the solvent has a higher boiling point than water, as is a common cause of housefires - for example if you have an oil fire, attempting to extinguish with water will lead to it sinking and instantaneously boil, launching hot, firey droplets everywhere and making the issue impossible to contain.

I only work with <100mL at a time so I’ve never had a fire myself, even when boiling 10-20 mL of solvents in a boiling tube using a blowtorch flame which I can do quite comfortably.

As for boiling chips, I use rough marble chips about 5-10mm in size that have been treated with dilute H2SO4 to form an inert and insoluble coating of CaSO4. These work pretty great for most applications and I’ve never had them interfere with a reaction. From personal experience, I too have attempted to use glass shards as chips but I’ve found that they cause the boiling to be more violent and tend to jump around a lot - mineral based chips produce more consistent nucleation with smaller bubbles leading to a gentle simmer/rolling boil.

[Edited on 13-1-2018 by LearnedAmateur]




In chemistry, sometimes the solution is the problem.
View user's profile View All Posts By User
NEMO-Chemistry
International Hazard
*****




Posts: 1258
Registered: 29-5-2016
Location: UK
Member Is Offline


[*] posted on 13-1-2018 at 08:07


Quote: Originally posted by LearnedAmateur  
I assume this is common knowledge but I’ll add it anyway since it hasn’t been mentioned - never use water to extinguish a solvent fire. Dumping water onto an immiscible solvent will just cause it to float and keep burning, riding the water and going where it flows, and spraying with a hose will likely end in the fire becoming even more widespread. Not so much a problem with ethanol and such (mist setting), but kerosene, DCM, toluene etc. is the real issue. An even bigger danger is if the solvent has a higher boiling point than water, as is a common cause of housefires - for example if you have an oil fire, attempting to extinguish with water will lead to it sinking and instantaneously boil, launching hot, firey droplets everywhere and making the issue impossible to contain.

I only work with <100mL at a time so I’ve never had a fire myself, even when boiling 10-20 mL of solvents in a boiling tube using a blowtorch flame which I can do quite comfortably.

As for boiling chips, I use rough marble chips about 5-10mm in size that have been treated with dilute H2SO4 to form an inert and insoluble coating of CaSO4. These work pretty great for most applications and I’ve never had them interfere with a reaction. From personal experience, I too have attempted to use glass shards as chips but I’ve found that they cause the boiling to be more violent and tend to jump around a lot - mineral based chips produce more consistent nucleation with smaller bubbles leading to a gentle simmer/rolling boil.

[Edited on 13-1-2018 by LearnedAmateur]


Boiling chips i use bits of broken coffee mugs, i have a regular and ample supply of these. they are normally heavily glazed and pretty inert IMHE.
View user's profile View All Posts By User
LearnedAmateur
Hazard to Others
***




Posts: 174
Registered: 30-3-2017
Location: Somewhere in the UK
Member Is Offline

Mood: Free Radical

[*] posted on 13-1-2018 at 09:07


I’ve heard that anything ceramic/porcelain based is fine for less stringent applications, plus it has some natural porosity to them. I have quite a collection of marble chips so I prefer those, plus they’re reusable with a small wash between uses - the only thing that turns me off of broken mugs is that the glazing does decrease surface area which is where the marble excels. Albeit, I’ve never used them, and since they’re recommended I don’t have anything to say against it, especially since mugs can be found in just about any home whereas marble may not.



In chemistry, sometimes the solution is the problem.
View user's profile View All Posts By User
NEMO-Chemistry
International Hazard
*****




Posts: 1258
Registered: 29-5-2016
Location: UK
Member Is Offline


[*] posted on 14-1-2018 at 03:46


Quote: Originally posted by LearnedAmateur  
I’ve heard that anything ceramic/porcelain based is fine for less stringent applications, plus it has some natural porosity to them. I have quite a collection of marble chips so I prefer those, plus they’re reusable with a small wash between uses - the only thing that turns me off of broken mugs is that the glazing does decrease surface area which is where the marble excels. Albeit, I’ve never used them, and since they’re recommended I don’t have anything to say against it, especially since mugs can be found in just about any home whereas marble may not.

My lab has a fresh broken mug most days :D, actually its the handles I break, if you want more surface area then an angle grinder does a fine job taking the glaze off.
View user's profile View All Posts By User
 Pages:  1  2

  Go To Top