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- Gao, Chuansi, et al.
(författare)
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Validation of standard ASTM F2732 and comparison with ISO 11079 with respect to comfort temperature ratings for cold protective clothing
- 2015
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 1872-9126 .- 0003-6870. ; 46:Online 17 July 2014, s. 44-53
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Tidskriftsartikel (refereegranskat)abstract
- American standard ASTM F2732 estimates the lowest environmental temperature for thermal comfort for cold weather protective clothing. International standard ISO 11079 serves the same purpose but expresses cold stress in terms of required clothing insulation for a given cold climate. The objective of this study was to validate and compare the temperature ratings using human subject tests at two levels of metabolic rates (2 and 4 MET corresponding to 116.4 and 232.8 W/m(2)). Nine young and healthy male subjects participated in the cold exposure at 3.4 and -30.6 °C. The results showed that both standards predict similar temperature ratings for an intrinsic clothing insulation of 1.89 clo and for 2 MET activity. The predicted temperature rating for 2 MET activity is consistent with test subjects' thermophysiological responses, perceived thermal sensation and thermal comfort. For 4 MET activity, however, the whole body responses were on the cold side, particularly the responses of the extremities. ASTM F2732 is also limited due to its omission and simplification of three climatic variables (air velocity, radiant temperature and relative humidity) and exposure time in the cold which are of practical importance.
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- Gao, Chuansi, et al.
(författare)
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Whole body heat balance and local insulation required to prevent extremity cooling in extremely cold environments
- 2016
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Ingår i: 6th International Conference on the Physiology and Pharmacology of Temperature Regulation. ; , s. 165-165
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Konferensbidrag (refereegranskat)abstract
- IntroductionLocal cooling in winter conditions is a sensitive and early warning of whole body cooling. Previous studies showed that the equilibrium temperature for the 5th finger is strongly affected by both temperature and insulation. The international standard ISO 11079 is used to calculate clothing insulation required for the whole body based on heat balance equations. However, it does not provide possibility to determine required insulation for local protection. The European standard EN 511 has provided a simple example of the thermal insulation level required as a function of ambient air temperature at a wind speed below 0.5 m/s. The objective of this study was to investigate the relationship between glove insulation and finger temperature in an extremely cold condition.MethodsNine subjects participated in a climatic chamber (Ta -30.6 °C, Va 0.4 m/s). Hestra wind stopper fleece fabric gloves and thicker cross country ski mittens (727 g/m2) with micro fleece lining were used for four and five subjects, respectively. Cold protective clothing (Icl=1.89 clo, standard total insulation: 2.26 clo) was used for subjects walking at 232.8 W/m2 to provide whole body thermal comfort according to ASTM F2732. Results and conclusionsThe rectal temperature was relatively stable (37.4 - 37.7 °C) during walking (90 min). The mean little finger temperature reduced to 7.9 (SD 1.4) °C when wearing Hestra wind stopper fleece fabric gloves (0.95 clo), whereas the finger temperature reached 17.8 (1.2) °C when wearing thicker ski mittens (1.46 clo). The insulation of gloves is required to be approximately about the standard total insulation of the ensemble (2.26 clo) to maintain thermal equilibrium of the finger (33 °C). The relationship (Iglove = 0.0522 * Tfinger + 0.5347) between finger temperature (°C) and glove insulation (clo) is established to estimate glove insulation required in this extremely cold environment.
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