title: Operational characteristics of liquid-conditioned suits.
abstract: The data from several studies of liquid-conditioned suits carried out over the last 12 years at the RAF Institute of Aviation Medicine have been collated, collectively reanalysed, and used to describe the characteristics of personal liquid-conditioning systems in terms of interactions between the conditioning and the conditioned system. Heat exchange across a liquid-conditioned suit (LCS) is shown to be proportional to the inlet temperature (Tin) of the conditioning liquid. Choice of Tin is determined, for resting subjects, primarily by the environmental temperature, by the length of the heat exchange tubing, and by the insulation value of the clothing worn over the LCS. Mean skin temperature (Tsk), but not core temperature (Tc) is directly related to Tin. However, certainly in exercising subjects, steady-state values for Tc can be increased by selecting very low values for Tin, which reduce Tsk below 29 degrees C. It is suggested that mean Tsk should not fall below 30 degrees C when the LCS is used for personal cooling. When the LCS is used for personal heating, sweating should be minimised, or prevented, by not allowing Tsk to rise to levels sufficient to cause an increase in Tc.
mesh_terms: D006358:Hot Temperature; D006801:Humans; D008297:Male; D008433:Mathematics; D011481:Protective Clothing; D012881:Skin Temperature; D013546:Sweating; D013696:Temperature; D013816:Thermodynamics