Thermal characteristics of diving garments when Using argon as a suit inflation gas

The thermal insulation characteristics of two drysuit ensembles, consisting of the same tri-laminate outergarment with differing thermal undergarments, were measured on a 21-zone thermal manikin at the Navy Clothing and Textile Research Facility (NCRTF) during immersion testing when using air and argon alternatively as the suit inflation gas. Total thermal insulation values were determined for both garments utilizing ASTM test standard F 1291 - standard test method for measuring the thermal insulation of clothing using a heated manikin. Improvements in localized thermal insulation values were seen throughout both drysuit ensembles when using argon as an inflation gas when compared with those while using air. Improvements with argon inflation in an experimental aerogel garment ranged from a low of 11% in the legs, 27% in the arms, and 22% in the torso. Overall, the total suit insulation increased with the aerogel garment by approximately 16%. Improvements with argon inflation in a commercial drysuit ranged from a low of 5% in the torso, 12% in the arms, to a high of 32% in the legs. Overall, the total suit insulation increased with the commercial garment by approximately 20%. This investigation demonstrated that significant improvements in drysuit thermal protection can be achieved when using argon instead of air as a drysuit inflation gas. It should be noted however that these improvements were achieved by carefully and repeatedly purging (a minimum of 6 purge cycles) with pure argon prior to water entry. It is hypothesized that reduced thermal improvements have been seen in practice due to inadequate suit purging prior to dives.