Figure 1

Way guidance systems for smoky conditions

 

a:Conventional code complying system:Spaced point sources of light

 

 

b:Continuous low location system at skirting board:Photoluminescent shown: location apply for electric back-lit systems also

 

 

c:Continuous low location photoluminescent system at floor center line

 

 

d:Continuous tactile system:Safety rail with directional notches - may include photoluminescent or powered marking

 

Figure 2

Visibility in heavy smoke

 

 

Region marked with the asterisk apply to guidance systems designed for light to heavy smoke.Note the convergence of both curves (incandescent white-photoluminescent black) towards zero visibility at 100% obscuration, indicating the insignific≠an≠ce of luminance-especially for class I smoke conditions (OD > 1.5) where visibility is less than 2 m.

 

 

 

Figure 3

Smoke density and visibility in the tests

 

 

Figures of smoke obscuration in %/m represent the smoke conditions at which the visual element of the guidance systems just about become invisible at max viewing distance.


Figur 4

Implications of High,Middle or Low Location Marking

In Smoky Conditions

 

 

 

 

 

Bildeforklaring med linje 3: WAIST LOCATION

Optimum visibility for the upright walking,  as well as crouching or crawling evacuees.

Marking may be tactile to anyone of the above.

Prevent undue crawling.

Point markings may be obscured by other people or objects,  while continuous marking accepts crowds 
and still appear linear.
Bildeforklaring med linje 3: HIGH LOCATION

All sources of light easily obstructed.

Continuous marking impractical:  
One looks down to seek step by step guidance.

Exit doors should have signs of high luminance located above, to cater for non-smoke conditions also.

 

Bildeforklaring med linje 3: LOW  LOCATION

Clean air layer persist for a short time or a short distance and within the smoke compartment only;  i.e. a non-typical condition encountered by evacuees in marked escape routes of complex structures.

Viewing distance from eyes of people walking too long.

May encourage undue crawling. Subject to tear and wear.
May be obstructed by people or objects