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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Technical Advice => Topic started by: GB on November 11, 2018, 06:34:49 PM

Title: Calculating tenability of radiation
Post by: GB on November 11, 2018, 06:34:49 PM
I have a scenario where I am trying to measure the radiative heat transfer and subsequent tenability within an open plan apartment and the relationship between cooking facilities and the means of escape.

I am considering using the calculation where:

q=Stefan-boltzman constant x T(absolute temp in Kelvin) x A (area of emitting body)

Would the forum agree this is the correct formula or is there another formula to prove that the radiative heat does not exceed 2.5Kw/m2?

If anyone has used this formula, is the temperature measured at the source of at the various points along the MoE?
Title: Re: Calculating tenability of radiation
Post by: lyledunn on November 12, 2018, 08:11:46 AM
I am not familiar with the formula. However, in dynamic context any constant involved surely means that the validity of the outcome is time limited?
Title: Re: Calculating tenability of radiation
Post by: Tom Sutton on November 12, 2018, 04:20:18 PM
My mathematics is limited to long division but a very long time ago we use to use a nomogram to measure the safe width of corridors, the information in the paper may be relevant to your OP.

Check out www.iafss.org/publications/frn/765/-1/view/frn_765.pdf you never know.
Title: Re: Calculating tenability of radiation
Post by: Fishy on November 13, 2018, 08:58:10 AM
It's been a while since I've done these, but it doesn't look right to me.  There's no emissivity in the equation, nor is there a configuration factor.  What you've got looks similar in form to the calculation for an emitted heat flux (I1 = εσT4), if you had assumed an emissivity of one, but that doesn't tell you what's falling on the 'receiver' (i.e. the occupants).

If I recall correctly, the SFPE Handbook is the 'go to' reference for this type of calculation.