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- Meinander, H, et al.
(författare)
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Manikin measurements versus wear trials of cold protective clothing (Subzero project)
- 2004
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 92:6, s. 619-621
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Tidskriftsartikel (refereegranskat)abstract
- The thermal insulation properties of clothing systems can be defined through physical measurements using thermal manikins or through wear trials using human test subjects. One objective of the European Subzero project was to define the relationship between physically measured thermal insulation values of cold-protective clothing and the corresponding physiological reactions on human test subjects. Four cold-protective clothing ensembles, intended for use in temperatures between 0 and -50degreesC, were measured with manikins in eight European laboratories and on human test subjects in four of these laboratories. The results showed that reasonably good reproducible values from the manikin tests can be achieved (CV <8%); however, the fit of the clothing on the manikin is a critical factor. There were greater individual differences in the wear trial results. Comparing the results from the manikin and the wear trials, good agreement in the thermal insulation values was shown if the amount of accumulated sweat was low. In these situations, which are normal when using cold protective clothing, the thermal comfort can also be determined with good accuracy by means of mathematical models based on manikin results. Special situations, e.g. for highly perspiring wearers, strong wind, or high friction between garment layers, need specific modelling; some suggestions have been made as a result of the Subzero project, but further research is required.
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| 2. |
- Geng, Q., et al.
(författare)
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Temperature limit values for touching cold surfaces with the fingertip
- 2006
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Ingår i: Annals of Occupational Hygiene. - : Oxford University Press (OUP). - 1475-3162 .- 0003-4878. ; 50:8, s. 851-862
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: At the request of the European Commission and in the framework of the European Machinery Directive, research was performed in five different laboratories to develop specifications for surface temperature limit values for the short-term accidental touching of the fingertip with cold surfaces. Methods: Data were collected in four laboratories with a total of 20 males and 20 females performing a grand total of 1655 exposures. Each touched polished blocks of aluminium, stainless steel, nylon-6 and wood using the distal phalanx of the index finger with a contact force of 1.0, 2.9 and 9.8 N, at surface temperatures from +2 to -40 degrees C for a maximum duration of 120 s. Conditions were selected in order to elicit varying rates of skin cooling upon contact. Contact temperature (T-C) of the fingertip was measured over time using a T-type thermocouple. Results: A database obtained from the experiments was collated and analysed to characterize fingertip contact cooling across a range of materials and surface temperatures. The database was subsequently used to develop a predictive model to describe the contact duration required for skin contact temperature to reach the physiological criteria of onset of pain (15 degrees C), onset of numbness (7 degrees C) and onset of frostbite risk (0 degrees C). Conclusions: The data reflect the strong link between the risk of skin damage and the thermal properties of the material touched. For aluminium and steel, skin temperatures of 0 degrees C occurs within 2-6 s at surface temperatures of -15 degrees C. For non-metallic surfaces, onset of numbness occurs within 15-65 s of contact at -35 degrees C and onset of cold pain occurs within 5 s of contact at -20 degrees C. The predictive model subsequently developed was a non-linear exponential expression also reflecting the effects of material thermal properties and initial temperature. This model provides information for the protection of workers against the risk of cold injury by establishing the temperature limits of cold touchable surfaces for a broad range of materials, and it is now proposed as guidance values in a new international standard.
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