Posted By Flic
Fascinating question!

I don't know the answer but I know the answer to a related question.

You can pick up an object that is 60 degrees C, but you wouldn't want to hold on to it for very long.

By the time it reaches 80 degrees you put it down in a hurry and swear a bit.

At the other end of the scale you can tolerate having small splashes of liquid nitrogen on the skin, although a large splash will burn you.

You can momentarily pass your hand across the top of a flame so that you singe the hairs on your hand, but suffer no burns.

So it depends on temperature and time!

Flic

Posted By Chris Packham
Andy

It will also depend upon the distance that the person is from the outlet. The hot air will mix with normal air and the temperature drops quite quickly with increasing distance.

Again not a precise answer, but I don't think there is one!

Chris

Posted By Pete48
Andy the link to the ROSPA site is:
http://www.rospa.com/pro...rticles/temperatures.htm

It doesn't cover air temperatures but it does give some useful info and references to standards.

I am puzzled as to why you want to test in the way you outline. What would it prove? Can you not do some design analysis and predictions on outcomes? Without thinking too greatly, wouldn't the discomfort factor cause people to move away from any danger area well before any burn from continued exposure? Any more dynamic failure would need to produce much higher temperatures in order to burn in less time. Then there is the inhalation aspect if we are dealing with heated air.
However, in case it might help you. I have a figure of above 50 degrees C in my head as an indicative temperature above which skin burns can generally be promoted but that would include hot surface contact temperatures.
Sorry I cannot recall a reference for you so you will have to treat my comments with caution until someone more competent comes along.

Posted By Andy Petrie
Thanks for all the answers so far, the heaters are at floor level so would be at the back of peoples ankles when they were sat down. We're trying to simulate the conditions of a very busy train where peoples bags and copies of the Metro are blocking the actual vent inlets and outlets to see what the temperature could rise to and to see if we need to install any further controls.

We've done some modelling but anyone who's worked on modelling air flows and heat transfer knows that you can't beat a real test to find the answer.

Posted By Paul Clarke-Scholes CMIOSH
The auto-ignition temperature for paper is reputed to be 451 degrees Fahrenheit, hence the name of the book. About 230 centigrade.

Don't suppose that helps though, unless you get to the point where the copy of the Metro blocking the vents bursts into flames!

Posted By D. Hilton
Andy
Try the following:

BSI BS EN 13202 Ergonomics of the Thermal Environment - Temperatures of Touchable Hot Surfaces - Guidance for Establishing Surface Temperature Limit Values in Production Standards.

EN 563 Safety of machinery. Temperatures of touchable surfaces. Ergonomics data to establish temperature limit values for hot surfaces

Posted By Steve Clark
Just to complicate things:
think about..it's not just ankles that might be near to the floor.

Handbags with the following in them ...

aerosols e.g. scent deodorant
bottles of prefume
cigarette lighters