Determination of clothing microenvironment volume

An improved method has been developed for determining the microenvironment volume of protective clothing assemblies. Subjects wearing four different helicopter pilot suits were enclosed in an impermeable polyvinyl outer suit. Air from within the enclosed environment was evacuated at a constant rate with a vacuum source until internal pressure decreased to − 30cm H2O. The volume of air evacuated from the microenvironment was estimated by integrating the exhaust flow rate. The inherent compliance of the polyvinyl outersuit was first converted into the volume Ve , during the trials for subjects wearing only jogging shorts. The clothing microenvironment volume (Vμ) was then calculated by subtracting Ve from the volume evacuated while subjects wore suits. The observed inter-individual variations in microenvironment volume reflect the subjects' different body sizes. It is concluded, that the new method enables faster determinations of Vμ and allows correction for the inherent compliance of the polyvinyl outersuit. In addition, the present method allows more objective determination of Vμ compared to the original method as proposed by Crockford and Rosenblum (1974).