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Lelia Lawson, Betty Crown, Mark Ackerman, & Doug Dale Protective Clothing and Equipment Research Facility The University of Alberta Moisture Effects in.

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Presentation on theme: "Lelia Lawson, Betty Crown, Mark Ackerman, & Doug Dale Protective Clothing and Equipment Research Facility The University of Alberta Moisture Effects in."— Presentation transcript:

1 Lelia Lawson, Betty Crown, Mark Ackerman, & Doug Dale Protective Clothing and Equipment Research Facility The University of Alberta Moisture Effects in Heat Transfer Through Clothing Systems for Wildlands Firefighting

2 Related Literature turn-out gear with moisture barriers or single layers used TPP- or RPP-type test devices and end points many different moisture applications (amount & location); results generally varied depending on moisture application

3 Objectives Examine the effects of location and source of moisture on heat transfer through materials comprising clothing systems worn by wildland firefighters. Examine alternative test procedures for measuring heat transmission through fabric systems.

4 primarily wildland (forest) firefighters structural firefighters workers in the oil and gas industry others that may be exposed to a harmful heat source Relevance To:

5 Individuals who partake in the “activities of fire suppression and property conservation in woodlands, forests, grasslands, brush, prairies, and other such vegetation, or any combination of vegetation, that is involved in a fire situation but is not within buildings or structures”. (NFPA, 1987)Individuals who partake in the “activities of fire suppression and property conservation in woodlands, forests, grasslands, brush, prairies, and other such vegetation, or any combination of vegetation, that is involved in a fire situation but is not within buildings or structures”. (NFPA, 1987) Wildland Firefighters

6 exposure to high temperature environmentsexposure to high temperature environments encounter moisture in many formsencounter moisture in many forms internal (perspiration)internal (perspiration) external:external: spray from fire hosesspray from fire hoses rain water or dewrain water or dew bog or lake waterbog or lake water Wildland Firefighters

7 moisture may increase or decrease heat transfer through a clothing system depending on:moisture may increase or decrease heat transfer through a clothing system depending on: degree of moisture sorptiondegree of moisture sorption location in the clothing systemlocation in the clothing system where it is located on the bodywhere it is located on the body its sourceits source its timing of applicationits timing of application

8 focus group interview with wildland firefighters in Whitecourt, Albertafocus group interview with wildland firefighters in Whitecourt, Alberta gain a better understanding of this environment and hazards to which wildland firefighters are exposedgain a better understanding of this environment and hazards to which wildland firefighters are exposed often exposed to internal and external moistureoften exposed to internal and external moisture implication that moisture presence increases heat transfer through thermal protective clothing systemsimplication that moisture presence increases heat transfer through thermal protective clothing systems Focus Group Interview:

9 Independent variables:Independent variables: four different fabric systemsfour different fabric systems five different moisture applicationsfive different moisture applications exposure to flame and radiant heat sourcesexposure to flame and radiant heat sources Dependent variables:Dependent variables: peak heat flux and total energy transferred through the fabric systems were measuredpeak heat flux and total energy transferred through the fabric systems were measured Experimental Design

10 Outer layer / Underwear layer: Aramid (221.5 g/m 2 ) / 100% cotton jersey knit (176.5 g/m 2 ), Aramid (221.5 g/m 2 ) / Aramid rib knit (164.0 g/m 2 ), FR Cotton (337.5 g/m 2 ) / 100% cotton jersey knit (176.5 g/m 2 ), FR Cotton (337.5 g/m 2 ) / Aramid rib knit (164.0 g/m 2 ). Fabric Systems

11 both outer and underwear fabrics oven dried prior to testingboth outer and underwear fabrics oven dried prior to testing both outer and underwear fabrics conditioned in a standard atmosphere (21°C and 65% relative humidity) prior to testingboth outer and underwear fabrics conditioned in a standard atmosphere (21°C and 65% relative humidity) prior to testing outer layer saturated prior to testingouter layer saturated prior to testing underwear layer saturated prior to testingunderwear layer saturated prior to testing both outer and underwear layers saturated prior to testingboth outer and underwear layers saturated prior to testing Moisture Application

12 specimens were tested using equipment for CAN/CGSB-4.2 No. 78.1: Thermal Protective Performance of Materials for Clothing with a 6.4mm spacer heat flux was set at 83kW/m² flame remained under specimen for 10 seconds (heat flux and total energy data were collected for 60 seconds) Flame Exposure (FE)

13 specimens were tested using equipment for NFPA 1977 Standard on Protective Clothing for Proximity Fire Fighting, section 6.2 Radiant Protective Performance with a 6.4mm spacer heat flux was set at 10kW/m² the specimens were exposed for 100 seconds (heat flux and total energy data were collected for 100 seconds) Radiant Exposure (RE)

14 Dependent Variables peak heat flux transferred through each specimen (fabric system) for both FE and REpeak heat flux transferred through each specimen (fabric system) for both FE and RE determined total energy transferred through each specimen at 60 seconds (FE) or 100 seconds (RE)determined total energy transferred through each specimen at 60 seconds (FE) or 100 seconds (RE) determined time to reach peak heat flux and time to reach 0.1 kJ for each specimen for both FE and REdetermined time to reach peak heat flux and time to reach 0.1 kJ for each specimen for both FE and RE

15 Flame Exposure (83 kW/m 2 )

16 Flame Exposure: Aramid Outer/FR Cotton Outer/ Cotton Underwear SystemCotton Underwear System Heat Flux Total Energy

17 Radiant Exposure (10 kW/m 2 )

18 Radiant Exposure: Aramid Outer/FR Cotton Outer/ Cotton Underwear SystemCotton Underwear System Heat Flux Total Energy

19 High-Heat-Flux Flame Exposure

20 Low-Heat-Flux Radiant Exposure

21 Conclusions: source and location of moisture do affect how heat is transferred through a clothing system:source and location of moisture do affect how heat is transferred through a clothing system: –at high heat fluxes, external moisture generally decreases heat transfer while internal moisture may increases heat transfer –at low heat fluxes, internal and external moisture decrease total energy transferred

22 Conclusions: layering of outer and underwear materials do affect how heat is transferred through a clothing system when moisture is present:layering of outer and underwear materials do affect how heat is transferred through a clothing system when moisture is present: –at high heat fluxes, fabric systems with an aramid generally had a better thermal protection than fabric systems with a FR cotton outer layer. –at low heat fluxes, thermal protection varied between fabric system depending on moisture application.

23 Implications: comfort:comfort: heat stress/fatigueheat stress/fatigue clothing systems:clothing systems: choice of fabric system relevant to environment, orchoice of fabric system relevant to environment, or design system to accommodate all conditionsdesign system to accommodate all conditions standard test method development:standard test method development: use of Stoll curve for an end point?use of Stoll curve for an end point? one test condition?one test condition? should consider end useshould consider end use

24 Further Research: examination of other moisture applications and their effect on heat transfer:examination of other moisture applications and their effect on heat transfer: moistened internally during exposuremoistened internally during exposure moistened externally after exposuremoistened externally after exposure full scale garment system testingfull scale garment system testing

25 Financial assistance from the Alberta Workers’ Compensation Board and the Department of Human Ecology and Faculty of Graduate Studies & Research at the University of Alberta.Financial assistance from the Alberta Workers’ Compensation Board and the Department of Human Ecology and Faculty of Graduate Studies & Research at the University of Alberta. The wildland firefighters employed by Alberta Land and Forest Service who participated in a focus group interview.The wildland firefighters employed by Alberta Land and Forest Service who participated in a focus group interview. Acknowledgements

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