Analysis and evaluation of the thermal performance of combinations of suits and life jackets in water

Abstract

Life jackets are essential life-saving devices, and also play an important role in the thermal protection of drowning victims in cold water. To better understand the thermal performance of the combinations of suits and life jackets in water, a thermal manikin named “Walter” in a water tank was used to simulate the environment surrounding the drowning person. Three sets of suits and three sets of life jackets form a total of 12 test combinations to simulate the clothes worn by drowning people. The thermal resistance of 12 combinations in water were measured according to ISO 15831 and heat transfer coefficients for the chest, back, upper arm, arm, thigh and leg of the 12 test combinations were calculated and compared. Results showed that the combinations of the clothes and life jacket efficiently lowered conduction and convective heat transfer coefficients in the water. The total thermal resistance of the 12 test combinations ranged from 0.011 to 0.054°C · m2/W. The post-hoc analysis revealed that the conductive thermal resistances of the clothing combinations with life jackets were all elevated compared to those of the clothing combinations without life jackets ( p < 0.001), showing that life jackets provide better thermal insulation. The linear regression indicated that the conductive thermal resistance of the test combination had a considerable impact on the convective heat transfer coefficient. This study helps to establish the systematic study of the thermal protection performance of life jackets.