"A bucket of light..."

[bruce]

It may be "common practice" to chuck liquid nitrogen about. But that doesn't make it safe, sensible or acceptable in a professional environment. I'd like to see the risk assessment that says it's OK to chuck this around in a lecture.

 

In a confined space - say something around the size of a typical lift - a spillage of around a cupful of liquid nitrogen is enough to suffocate you.

[AndrewR]

As to the whole pouring light thing, a high intensity light under a false and transparent bottom in the bucket. Pour water out of the bucket and the water will act like a fibreoptic strand and the light will shine where the water hits something. An effect I remember Carol Vauderman demonstrating on How2 many years ago.

 

As to liquid nitrogen, if you know what you're doing then its not that dangerous. Ventilation and quantity being the main causes of hazards. DONT DO THIS but it is possible to pour it onto your unprotected skin and not be injured, as the liquid floats on a layer of nitrogen 'steam' produced when it hits you lovely warm skin. Obviously this is incredibly dangerous if you DONT know EXACTLY what you are doing.

And a chap gave himself a honarable mention in the darwin awards, after pouring liquid nitrogen into his mouth. Again IF you know what you are doing it possible to do this and blow nitrogen smoke rings, if you dont know what you are doing (he didnt, he'd just seen it once) then you end up with burns to vocal cords, and all sorts of other damage (he swallowed some of it) as the nitrogen expands inside.....

As mentioned by many others, potentially very dangerous.

[zonino]

It may be "common practice" to chuck liquid nitrogen about. But that doesn't make it safe...

 

I didn't say it was safe! and thats why we never travel when there's dewar's in the lift, and theres notices on every lift through the science blocks with notices to that effect

 

and as andrewR says, if you know what your doing it makes it alot less dangerous, just like anything in life

[Ben...]

It may be "common practice" to chuck liquid nitrogen about. But that doesn't make it safe...

 

Well, I've seen one, and it looked ok to me. If you look at the physics it's actually suprisingly safe; I've spilt a fairly large pot of liquid nitrogen on my (trainer clad) foot, and felt nothing apart from a chill.

[bruce]

it looked ok to me. If you look at the physics it's actually suprisingly safe; I've spilt a fairly large pot of liquid nitrogen on my (trainer clad) foot, and felt nothing apart from a chill.

 

Just because it "looked Ok to you" and because it didn't hurt on that one occasion, doesn't make it safe!

 

The point I'm making is that this is a dangerous chemical - not only because it's extremely cold, but because a spillage in a confined space can easily cause suffocation. People have died because of accidental spillages - at least 2 cases have been cited in this thread.

 

I'm not saying it can't be used safely - with appropriate training and safety precautions it can be handled as safely as any other substance. I spent years working with the stuff.

 

But messing about with it - eg chucking it about in a lecture - even if you can justify the safety on that particular occasion - is hardly the way for a professional to behave, especially in an educational environment where you're supposed to be passing on knowledge. You might know it's safe on that occasion, but can you guarantee that your audience won't subsequently just assume that it's OK to mess around with the stuff, and cause some real damage?

 

Bruce.

[zonino]

I should mention it was a chemistry degree lecture

[bruce]

I should mention it was a chemistry degree lecture

 

And what difference does that make? In many ways it justifies what I'm saying - you get some bonkers lecturer messing around with liquid nitrogen - maybe I am doing him/her a disservice, maybe it was a carefully controlled environment - but the end result is that the class conclude that "pissing about with N2 is OK...". Tell that to the family of the dead technician in Edinburgh.

 

In my experience I have found that while the lecturers and academics in science and engineering may have a phenomenal grasp of the theory and sometimes even the practice behind the science, their "common sense" is often sadly lacking, especially when it comes to health and safety.

 

This is real world experience - I work in a University, although I left the "academic" world about 15 years ago. My team and our subcontractors often have to carry out cabling works in science laboratories, and the lack of awareness of basic H&S is often astounding. Academics often cannot understand why our cabling team is unwilling to carry out work in a chemistry lab while they are still working!!

 

Some requests we've had:

 

"Can you install 5 network sockets, without turning the lights on"

"Can you install.... but be careful not to disturb the test tubes on the bench where you are working. The contents are very dangerous."

"Can you take off you safety boots before going into the room (to drill a large hole in a brick wall)"

 

In each case, the answer was "No"....

 

has this drifted far enough off-topc yet

[Ben...]

it looked ok to me. If you look at the physics it's actually suprisingly safe; I've spilt a fairly large pot of liquid nitrogen on my (trainer clad) foot, and felt nothing apart from a chill.

Just because it "looked Ok to you" and because it didn't hurt on that one occasion, doesn't make it safe!

 

Sorry, my quote of your post got mangled: what I meant was that I'd seen the risk assessment, and it seemed to be well written, taking into consideration all the appropriate hazards. I also had to go through the RAs for the lab work, and the controls for spillage were the quantities involved, ventilation and appropriate clothing (no sandals...) I believe it was safe.

 

But messing about with it - eg chucking it about in a lecture - even if you can justify the safety on that particular occasion - is hardly the way for a professional to behave, especially in an educational environment where you're supposed to be passing on knowledge. You might know it's safe on that occasion, but can you guarantee that your audience won't subsequently just assume that it's OK to mess around with the stuff, and cause some real damage?

That's a tad disingenous; fireworks, laser light shows and dry ice at concerts are messing about with dangerous things, and amateur imitators often get injured. I'd say that that's no reason for professionals not to muck around with it safely.

 

Ben

[bruce]

That's a tad disingenous; fireworks, laser light shows and dry ice at concerts are messing about with dangerous things, and amateur imitators often get injured. I'd say that that's no reason for professionals not to muck around with it safely.

 

The difference, of course, is that the events you list are purely entertainment events. You're putting on a show for an audience. It's scripted. There will be stringent risk assessments behind the scenes. There's no "mucking around".

 

"Mucking about" in an educational context - a lecture, where you're supposed to be teaching safe working practices for hazardous materials - is a completely different kettle of fish...