Effect of Air Gap Entrapped in Firefighter Protective Clothing on Thermal Resistance and Evaporative Resistance

Abstract Heat and water vapor transfer behavior of thermal protective clothing is greatly influenced by the air gap entrapped in multilayer fabric system. In this study, a sweating hot plate method was used to investigate the effect of air gap position and size on thermal resistance and evaporative resistance of firefighter clothing under a range of ambient temperature and humidity. Results indicated that the presence of air gap in multilayer fabric system decreased heat and water vapor transfer abilities under normal wear. Moreover, the air gap position slightly influenced the thermal and evaporative performances of the firefighter clothing. In this study, the multilayer fabric system obtained the highest thermal resistance, when the air space was located at position B. Furthermore, the effect of ambient temperature on heat and water vapor transfer properties of the multilayer fabric system was also investigated in the presence of a specific air gap. It was indicated that ambient temperature did not influence the evaporative resistance of thermal protective clothing. A thermographic image was used to test the surface temperature of multilayer fabric system when an air gap was incorporated. These results suggested that a certain air gap entrapped in thermal protective clothing system could affect wear comfort.

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Quantitative assessment of the thermal stored energy in protective clothing under low-level radiant heat exposure

Textile Research Journal ◽

10.1177/0040517517732084 ◽

2017 ◽

Vol 88 (24) ◽

pp. 2867-2879 ◽

Cited By ~ 1

Author(s):

He Jiazhen ◽

Chen Yan ◽

Wang Lichuan ◽

Li Jun

Keyword(s):

Energy Storage ◽

Thermal Resistance ◽

Thermal Energy ◽

Protective Clothing ◽

Heat Exposure ◽

Radiant Heat ◽

Air Gap ◽

Heat Fluxes ◽

Total Thermal Resistance ◽

Fabric System

In addition to direct thermal energy from a heating source, a large amount of thermal energy stored in clothing will continuously discharge to the skin after exposure. Therefore, thermal protective clothing may have a dual effect on human skin in reality. An experimental investigation was conducted to study the energy storage within 15 different combinations of clothing layers exposed to low heat fluxes ranging from 2.5 kW/m2 to 8.5 kW/m2. The energy storage process, the distribution of energy storage, and variables critically impacting energy storage, including fabric layers, air gap under clothing, thermal resistance and heat source intensity were discussed. It is demonstrated that the weight and thickness of the fabric are dominating factors affecting energy storage. For a multilayer fabric system, 36–57% of the total amount of energy is stored in the outer shell. The neighboring layer proves to be very important for the energy storage in an individual fabric. The air gap that exists between the fabric and the skin exerts an influence on the energy storage within fabric layers. In addition, a linear correlation is observed between the energy storage and the total thermal resistance of a fabric system. The research findings will be brought to researchers to better understand the mechanism and factors associated with energy storage and help develop new fabric combinations in order to minimize heat transmission to the skin.

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Thermal and moisture behavior of a multi-layered assembly in a pneumatic compression device

Textile Research Journal ◽

10.1177/00405175211006942 ◽

2021 ◽

pp. 004051752110069

Author(s):

Nimesh Kankariya ◽

Cheryl A Wilson ◽

Raechel M Laing

Keyword(s):

Water Vapor ◽

Thermal Resistance ◽

Total Surface Area ◽

Skin Layer ◽

Vapor Transfer ◽

Knit Fabrics ◽

Pneumatic Compression Devices ◽

Set Up ◽

Compression Treatment ◽

Water Vapor Transfer

The objective of this research was to determine the effect of multiple layers of materials typical of those used in air pneumatic compression devices (which require air impermeable layers to function) on thermal and water vapor resistance. The experimental set-up included: (a) single layers of two next-to-skin knit fabrics in both relaxed and extended conditions, (b) two layers of silicone, and (c) a multi-layered assembly comprised of a next-to-skin fabric and two layers of silicone. Structural properties (thickness, mass) dominated thermal resistance of the multi-layered assembly, and the silicone layers rendered this assembly impermeable to water vapor as expected. Results confirmed the need for some form of 'ventilation' to facilitate water vapor transfer from a potential user’s skin to the environment. By creating 18 circular vents across the silicone layers (each vent 314 mm2), which formed ventilation of ∼2% of total surface area, the water vapor resistance of the multi-layered assembly dropped significantly from very high (but non-measurable) to below ∼300 m2 Pa/W, although ventilation did not improve the thermal resistance of the multi-layer arrangements. Results of this research will enable manufacturers of pneumatic compression devices to develop devices comprised of a multiple layer arrangements i.e. a knit fabric next-to-skin layer and silicone layers with optimized vents across the silicone layers, so that the user can continue the compression treatment with an acceptable microenvironment.

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Thermal performance of fire fighters' protective clothing. 1. numerical study of transient heat and water vapor transfer

10.6028/nist.ir.6881 ◽

2002 ◽

Cited By ~ 15

Author(s):

Kuldeep Prasad ◽

William Twilley ◽

J Randall Lawson

Keyword(s):

Water Vapor ◽

Thermal Performance ◽

Protective Clothing ◽

Numerical Study ◽

Fire Fighters ◽

Vapor Transfer ◽

Water Vapor Transfer

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Experimental Study on Heat and Water-Vapor Transfer in a Moisture Adsorbing/Desorbing, Heat-Generating Fiber Material by Thermal Visualization Using an Infrared Thermography and These Numerical Analysis

Sen i Gakkaishi ◽

10.2115/fiber.70.160 ◽

2014 ◽

Vol 70 (7) ◽

pp. 160-166 ◽

Cited By ~ 2

Author(s):

Takeshi Ogino ◽

Hiroshi Tanaka

Keyword(s):

Experimental Study ◽

Water Vapor ◽

Numerical Analysis ◽

Infrared Thermography ◽

Fiber Material ◽

Vapor Transfer ◽

Water Vapor Transfer

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Effect of hot calendering on physical properties and water vapor transfer resistance of bacterial cellulose films

Journal of Materials Science ◽

10.1007/s10853-016-0112-4 ◽

2016 ◽

Vol 51 (21) ◽

pp. 9562-9572 ◽

Cited By ~ 6

Author(s):

V. L. D. Costa ◽

A. P. Costa ◽

M. E. Amaral ◽

C. Oliveira ◽

M. Gama ◽

...

Keyword(s):

Water Vapor ◽

Physical Properties ◽

Bacterial Cellulose ◽

Transfer Resistance ◽

Cellulose Films ◽

Vapor Transfer ◽

Water Vapor Transfer

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A categorization tool for fabric systems used in firefighters' clothing based on their thermal protective and thermo-physiological comfort performances

Textile Research Journal ◽

10.1177/0040517518809055 ◽

2018 ◽

Vol 89 (16) ◽

pp. 3244-3259 ◽

Cited By ~ 2

Author(s):

Sumit Mandal ◽

Simon Annaheim ◽

Andre Capt ◽

Jemma Greve ◽

Martin Camenzind ◽

...

Keyword(s):

Performance Index ◽

Protective Clothing ◽

High Performance ◽

Clustering Algorithm ◽

Health And Safety ◽

Thermal Protective Performance ◽

Thermal Protective Clothing ◽

Low Performance ◽

Fabric System ◽

Protective Performance

Fabric systems used in firefighters' thermal protective clothing should offer optimal thermal protective and thermo-physiological comfort performances. However, fabric systems that have very high thermal protective performance have very low thermo-physiological comfort performance. As these performances are inversely related, a categorization tool based on these two performances can help to find the best balance between them. Thus, this study is aimed at developing a tool for categorizing fabric systems used in protective clothing. For this, a set of commercially available fabric systems were evaluated and categorized. The thermal protective and thermo-physiological comfort performances were measured by standard tests and indexed into a normalized scale between 0 (low performance) and 1 (high performance). The indices dataset was first divided into three clusters by using the k-means algorithm. Here, each cluster had a centroid representing a typical Thermal Protective Performance Index (TPPI) value and a typical Thermo-physiological Comfort Performance Index (TCPI) value. By using the ISO 11612:2015 and EN 469:2014 guidelines related to the TPPI requirements, the clustered fabric systems were divided into two groups: Group 1 (high thermal protective performance-based fabric systems) and Group 2 (low thermal protective performance-based fabric systems). The fabric systems in each of these TPPI groups were further categorized based on the typical TCPI values obtained from the k-means clustering algorithm. In this study, these categorized fabric systems showed either high or low thermal protective performance with low, medium, or high thermo-physiological comfort performance. Finally, a tool for using these categorized fabric systems was prepared and presented graphically. The allocations of the fabric systems within the categorization tool have been verified based on their properties (e.g., thermal resistance, weight, evaporative resistance) and construction parameters (e.g., woven, nonwoven, layers), which significantly affect the performance. In this way, we identified key characteristics among the categorized fabric systems which can be used to upgrade or develop high-performance fabric systems. Overall, the categorization tool developed in this study could help clothing manufacturers or textile engineers select and/or develop appropriate fabric systems with maximum thermal protective performance and thermo-physiological comfort performance. Thermal protective clothing manufactured using this type of newly developed fabric system could provide better occupational health and safety for firefighters.

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