2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
temperature and the influence of vasoconstriction, we attempted to create a climatic wearing
comfort database for the handwear under investigation.
Based on the data from the study mentioned above (Glitz et al., 2005) the heat flow into the
phantom was decreased gradually in dependence on the measured skin temperature (palm
region) from a chosen maximum heat flow at Tskin = 31°C, down to the lowest value for Tskin
≤ 15°C. The value for the maximum heat flow was varied between 2 and 7 W (starting
parameter at normal skin temperature) in four steps, simulating different work loads
(metabolic rate). In all cases, the environmental temperature in the climate chamber was
lowered continuously from 0°C to -40°C in a period of 120 min (cooling rate: 0.33 K/min).
The temperature of the climate chamber as well as the skin temperature of the hand phantom
were monitored with thermal sensors, and plotted as a function of time. Table 1 shows the
results of the measurement. The temperature limit of the comfort range was taken from plots
of skin temperature as a function of environmental temperature, at the point where Tskin =
15°C of the phantom, for the various chosen maximum heat flows.
Table 1: Environmental temperature limit of the comfort range of the glove depending on the
heat flow into the phantom (metabolic rate).
heat flow 2 W heat flow 3 W heat flow 5 W heat flow 7 W
Temperature limit
of the comfort range
-9 o C -11 o C -17 o C -25 o C
In a comparable measurement, where the heat flow into the phantom was not a function of
skin temperature, but constant over the whole skin temperature range, the decrease of skin
temperature with decreasing outside temperatures was much slower. As a consequence, the
estimated values for the temperature limit using the same variety of given maximum heat
flows, were significantly lower, and between -11 o C (2 W) and -33 o C (7 W). It is obvious that
the consideration of the vasoconstriction in the simulation measurements leads to a more
physiologically-based and reliable prediction of the comfort range, with great relevance for
the safety of soldier, and can protect from serious cold injuries under extreme cold conditions.
The database of the temperature limits for the predicted comfort range of the special cold and
wet protecting glove should be completed with the estimation of maximum time periods for
wearing within the thermal comfort range. Again the limit criterion is the maintenance of a
minimum skin temperature of 15 o C over this time. In various scenarios with different
parameters concerning environmental temperature and heat flow into the phantom (metabolic
rate), a database for a safe time of use was estimated. As an example, Table 2 shows the
estimated safe time of use in dependence on various metabolic rates (maximum heat flow at
normal skin temperature) at an extreme environmental temperature of -17 o C.
Table 2: Estimation of maximum wearing time within the thermal comfort range (safe time of
use) depending on the heat flow into the phantom (metabolic rate).
heat flow 2 W heat flow 3 W heat flow 5 W heat flow 7 W
Safe time of use
(within the comfort range)
20 min 25 min 30 min 40 min
In the case of a heat flow of 5 W, the maximum wearing time within the thermal comfort
range would increase from 30 min to 1 h with an environmental temperature of –5 o C. It
should be mentioned that, after the estimated time periods, cold injuries are not inevitable, but
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