Seating in church hall

[BLEVE]

Agree totally,
It would have been better to have at least used different groups of students from different reas of the campus for each experiment.

I supoose that given todays litigious climate it would have been difficult to have carried out the study unanounced for fear of injury.

Common sense tells me that given reduced spacing between rows, reduced egress widths and given the required visual cues e.g. smoke initiating some degree of evacuation and flame initiating a greater and more urgent rate of evacuation, it would be expected that a number of chairswould become displaced.

[nearlythere]

More displaced chairs yes but to a level so as to be a significant and unacceptable risk?

[BLEVE]

That depends on the number, location of chairs displaced,number of occupants taking part in the evac, number of MOE provided and strength of cue to initiate evac action.

Maybe the potential to model this but would offfer the opinion that direct experiment is the way to go.

I would also agree and offer the opinion that given reduced row length and generous access/egress dimension, then I would not have thought the number of displaced chairs would prevent complete evacuation until conditions became untenable.  

[kurnal]

If I had the time and it was not considered by some as being clever, I would calculate and compare PolyP vs Timber chair HRR, RHF, Tig and Tg.

I would be interested in seeing the results of this please Bleve. Having seen PolpyP baking trays and pallets burning I am concerned about this from a property protection, firefighter safety and  environmental protection viewpoint.

[BLEVE]

Will give a go as soon as get a chance

[BLEVE]

From calculations, as we expected, it seems that the PP chair is the greater fire risk.

Interesting to note that if timber seats are positioned at a distance in excess of 0.35 metres then fire spread from timber seat to timber seat is not an issue as the piloted heat flux value cannot be achieved.

Also of apparent interest is the case whereby the PP seating material combusts and falls to the floor resulting in a viscous pool. Where a number of stacked seats are involved in fire, this may result in an additional volume of PP at the floor surface/pool resulting in an increased heat flux.

For anyone interested, the results are posted at

http://www.hugedrive.com/published/WG/show.php?q=SElMVFNGSUxFUw==-392debf5

 
  

[kurnal]

Thanks Bleve. Thats an interesting comparison. I wonder how easily they are ignited?

[Tom Sutton]

BLEVE on your first graph regarding PP it showed no significant rise in temp for about ten minutes then a rapid rise. To me this indicates it took 10 mins to get started but then the temp rose rapidly evolving a great deal of heat. Also when they are stacked they pose the greatest danger, would you agree.

[BLEVE]

Tom
It would seem that the stacked chairs result in a pool of greater surface area and heat release.

If we take the ignition temperature listed for the PP seats then piloted ignition is calculated as 7.6 kW/m2

If we consider the advised critical heat flux for ignition without pilot 20 kW/m2, we then require some 769 kelvin in order to initiate combustion of the first seat in the stack.

[BLEVE]

Mr or Ms arsonist would need only 125 ml Ethanol and a match to initiate combustion,
This results in a HRR of 44 kW and RHF of 25 kW/m2 at source

[BLEVE]

Of course they could always use a church candle,
21 mm dia candle provides heat flux of 65 kW/m2 at 50 mm above flame.

[Tom Sutton]

DOH