title: Correction factors for assessing immersion suits under harsh conditions.
abstract: Many immersion suit standards require testing of thermal protective properties in calm, circulating water while these suits are typically used in harsher environments where they often underperform. Yet it can be expensive and logistically challenging to test immersion suits in realistic conditions. The goal of this work was to develop a set of correction factors that would allow suits to be tested in calm water yet ensure they will offer sufficient protection in harsher conditions. Two immersion studies, one dry and the other with 500 mL of water within the suit, were conducted in wind and waves to measure the change in suit insulation. In both studies, wind and waves resulted in a significantly lower immersed insulation value compared to calm water. The minimum required thermal insulation for maintaining heat balance can be calculated for a given mean skin temperature, metabolic heat production, and water temperature. Combining the physiological limits of sustainable cold water immersion and actual suit insulation, correction factors can be deduced for harsh conditions compared to calm. The minimum in-situ suit insulation to maintain thermal balance is 1.553-0.0624·TW + 0.00018·TW(2) for a dry calm condition. Multiplicative correction factors to the above equation are 1.37, 1.25, and 1.72 for wind + waves, 500 mL suit wetness, and both combined, respectively. Calm water certification tests of suit insulation should meet or exceed the minimum in-situ requirements to maintain thermal balance, and correction factors should be applied for a more realistic determination of minimum insulation for harsh conditions.
authors.affiliation: National Research Council of Canada, 1 Arctic Avenue, St. John's, NL, A1B3T5, Canada. Electronic address: jonathan.power@nrc.ca.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Power
authors.affiliation: Defence R&D Canada, 1133 Sheppard Avenue West, Toronto, ON, M3K2C9, Canada. Electronic address: peter.tikuisis@drdc-rddc.gc.ca.
authors.forename: Peter
authors.initials: P
authors.lastname: Tikuisis
authors.affiliation: National Research Council of Canada, 1 Arctic Avenue, St. John's, NL, A1B3T5, Canada. Electronic address: antonio.simoesre@nrc.ca.
authors.forename: António Simões
authors.initials: AS
authors.lastname: Ré
authors.affiliation: Department of Sport and Exercise Science, University of Portsmouth, Winston Churchill Avenue, Portsmouth, PO12UP, United Kingdom. Electronic address: martin.barwood@northumbria.ac.uk.
authors.forename: Martin
authors.initials: M
authors.lastname: Barwood
authors.affiliation: Department of Sport and Exercise Science, University of Portsmouth, Winston Churchill Avenue, Portsmouth, PO12UP, United Kingdom. Electronic address: michael.tipton@port.ac.uk.
authors.forename: Michael
authors.initials: M
authors.lastname: Tipton
mesh_terms: D000328:Adult; D003080:Cold Temperature / Q000009:adverse effects; D006801:Humans; D007035:Hypothermia / Q000209:etiology / Q000517:prevention & control; D007101:Immersion / Q000009:adverse effects; D008297:Male; D055641:Mathematical Concepts; D011481:Protective Clothing / Q000592:standards*; D012881:Skin Temperature; D013814:Thermal Conductivity; D022722:Thermogenesis; D014867:Water; D014919:Wind; D055815:Young Adult
chemical_list: D014867:Water
keywords: Correction factors; Hypothermia; Immersion suits