THE EFFECT OF WATER LEAKAGE ON THE RESULTS OBTAINED FROM HUMAN AND THERMAL MANNEQUIN TESTS OF IMMERSION PROTECTIVE CLOTHING

The effect of both the volume and location of water leakage on the pro tection provided by an uninsulated immersion suit was investigated usi ng human subjects and, in corresponding experiments, an immersion ther mal manikin. Three volumes of ''leakage'' to the torso (200, 500 and 1 000 ml) were examined, as were two conditions in which no leakage was simulated and one condition in which a 500-ml leak to the limbs was si mulated. All leakages were introduced in a standardised way before imm ersion. The measurements of clothing insulation obtained, both rom the manikin and the humans, were in general agreement. The hub man experi mentation provided some support for a 200-ml limit to water leakage in tests of immersion suits. Rectal and aural temperatures remained sign ificantly (P < 0.05) higher when a 500-ml leak was applied to the limb s rather than the torso; this was primarily due to greater heat flow t hrough and from the torso (back) during the immersions with torso wett ing. The physiological responses and anthropometric characteristics wh ich determine this response are not present in manikins; the implicati ons of this for the application and design of immersion thermal maniki ns, as well as the protection of those at risk of immersion in cold wa ter, are discussed. It is concluded that using immersion thermal manik ins to provide a single overall measure of clothing insulation will no t necessarily distinguish between suits which provide quite different levels of protection for humans.