Analysis of air gap volume in structural firefighter turnout suit constructions in relation to heat loss

Abstract

Air layers in multi-layer firefighter clothing ensembles resist heat transfer from the body to the environment. By reducing the volume of air between clothing layers, heat loss may be improved throughout the multi-layer firefighter turnout suit clothing system, potentially leading to reduced heat strain for the wearer. This research utilized a systems-level approach to the methodology in order to measure the effects of fabric properties and garment air gap dimensions on clothing system heat loss through specially configured turnout suit constructions. One experimental configuration incorporated a tight fitting stretchable moisture barrier garment. Another construction used thermal knit underwear to represent a closer fitting thermal liner. Air gap surface area, volume, and thickness were estimated using three-dimensional body scanning. This study showed the significant impact of fabric air permeability and clothing air gap volume on heat loss through structural firefighter suits. Tested individually, the tighter fitting moisture barrier construction permitted greater heat loss in comparison to the traditional fit moisture barrier. Heat loss differences associated with moisture barrier fit were not observed when the moisture barriers were configured in the three-layer turnout clothing system. This research showed that microclimate air gap volume is strongly correlated with total heat loss. It confirmed the significant impact of clothing air layers on heat loss through firefighter turnout systems.

A critical review of female firefighter protective clothing and equipment workplace challenges

“…Oversized, heavy, ill-fitting protective garments also create larger air gaps within the clothing microclimate or the atmosphere between the body and the garment (Havenith, 2001; Frackiewicz-Kaczmarek et al , 2015). As these gaps of air thicken or increase in size, clothing insulation also increases, thereby reducing heat transfer and effective evaporation of sweat leading to overheating (Havenith, 2001; Bouskill et al , 2002; McQuerry et al , 2017). Areas of the turnout suit that are oversized and bulky not only elevate the risk of trips and falls but also increase the thermal and evaporative resistance as heat must travel farther away from the body to be effectively released through the clothing ensemble to the external environment (Havenith, 2001; McQuerry et al , 2017).…”

“…As these gaps of air thicken or increase in size, clothing insulation also increases, thereby reducing heat transfer and effective evaporation of sweat leading to overheating (Havenith, 2001; Bouskill et al , 2002; McQuerry et al , 2017). Areas of the turnout suit that are oversized and bulky not only elevate the risk of trips and falls but also increase the thermal and evaporative resistance as heat must travel farther away from the body to be effectively released through the clothing ensemble to the external environment (Havenith, 2001; McQuerry et al , 2017). For female firefighters who often select oversized turnout gear, to accommodate their bust and hips, large air gaps due to excessive bulk may be prominent throughout their clothing microclimate.…”

A validation study on the thermal simulation of the human body-clothing-environment system through wear trials

“…Microclimate has a very important role in the thermal regulation of any clothing system. [12][13][14] Since microclimate is affected by many factors like continuously changing ambient environment, thermophysiological properties of the relevant body element, and characteristics of the clothing, therefore complex thermal transportation phenomenon exist in microclimate. Previously, many thermal simulation methods for the human body-clothing-environment system have been proposed based on the principle that either the air gap underneath the clothing has a constant thickness or does not exist.…”

The Volumetric Analysis of the Human Body as Starting Point for Clothing Pattern Design

“…According to that, the dry heat loss from the body is a combination of both the resistance provided by the clothing and from the entrapped microclimatic air, apropos the heat transferred by the exposed skin and the heat passing through the clothing [11]. The garment fit and resultant air volume is a crucial factor in determining thermal insulation value of clothing ensembles [5,[12][13][14]. The thermal insulation will increase almost linearly with air gap amplification, as long no convection is present [5,15,16].…”