Evaluation of Exit Signs in Clear and Smoke Conditions.
Evaluation of Exit Signs in Clear and Smoke Conditions.
(1140 K)
Collins, B. L.; Dahir, M. S.; Madrzykowski, D.
NISTIR 4399; 80 p. August 1990.
Order number: PB90-269523
Keywords:
smoke; color; exits; optical density; egress; lighting
equipment; visibility
Abstract:
The present paper provides a short review of the
research literature on the visibility of exit signs,
directional markings, and emergency lighting. It also
presents a study which assessed the visibility of
several types of exit signs including conventional and
electroluminescent (EL) in both clear and smoky
conditions. A two-part evaluation was performed. In
the first, signs were measured photometrically in clear
conditions with two different photometers in a
laboratory to determine their luminance under dark
conditions and with an ambient room illuminance of 54 1x
(5 fc). Analysis of these data indicated very wide
variations in luminance (from about 0.9 to 1350 cd/m2)
as a function of sign type. In the second part of the
study, the visibility of the signs in both clear
conditions and smoke was assessed psychophysically. A
total of 21 observers participated in the assessment of
visibility. Analysis of the data indicated that overall
sign luminance was one of the primary determinants of
visibility in smoke conditions, while uniformity was
also an important contributor. The data indicated that
some EL signs can be effective in clear conditions and
in smoke (particularly if their luminance is above about
10 cd/m2). Consideration of the results indicated that
somewhat different characteristics of the signs seemed
to determine their visibility for clear conditions than
smoke, with uniformity (or sign configuration) playing a
larger role in clear conditions, and luminance being
more critical in smoke. Finally, the data indicated the
need for further research in which the effects of color,
sign configuraiton, and luminance are varied
parametrically.
