IES940378A2 - Improved protective clothing - Google Patents

Abstract

Protective or other clothing in which the ability ofthe clothing to lose or gain heat by radiation from the environment, other clothing layers or the wearer’s body is modified by selecting materials or surface coatings for outer, internal or inner surfaces which have the required reflective or absorbtive characteristics for the ultra-violet, visible light or infra-red wavelengths generated by the temperatures ofinterest. Protective clothing which incorporates reflective surfaces 12 and 14 so located that internal heat transfer by radiative processes is minimised.

Description

Protective clothing can be used for reasons which include protecting the body against airborne dusts, gases or vapours or protecting the body against extremes of heat or cold. Protective clothing may also be required to provide protection simultaneously against airborne substances and extremes of heat or cold.

If protective clothing is worn to protect against airborne dusts etc. it is important that the clothing seals to the body at openings at the neck or ankles etc. However, for moderate or harder work in warm or hot environments, well sealed clothing can cause heat stress unless the clothing permits suffient heat loss from the body through the fabrics of construction by heat conduction or air or water vapour permeation. Unless sufficient heat can be lost through the clothing, wear durations may need to be limited to prevent the wearer being exposed to health or life threatening heat stress. Conversely, for light work in moderate or cold conditions, the body may lose too much heat and the wearer may suffer from cold stress. In extreme situations wear and exposure durations to the cold may need to be limited to prevent the wearer being exposed to health or life threatening cold stress.

Heat transfer through clothing is generally by conduction with heat loss or gain by convection and/or radiation at surfaces of the clothing which are not in physical contact with other surfaces. Although the use of reflective fabrics has frequently been adopted in firemens' clothing to protect against thermal radiation, the deliberate modification of protective clothing heat transfer by means of reflective or emissive surfaces has not been generally adopted.

Where such reflective surfaces have been used, these surfaces have typically been on the outermost layer only.

This invention describes means by which heat transfer through protective clothing can be increased or decreased as required by selecting internal, interior and/or external surfaces with the required reflective or emissive characteristics at the wavelengths generated by the temperatures of interest. -. 94 0 37 8 ’ Because outer clothing or underclothing frequently is not completely in direct contact with the underclothing or body respectively, and because human skin is a very good absorber and emitter of infra-red radiation, heat transfer could be controlled as desired by suitably selecting the reflective characteristics of the underclothing surfaces and of the inner surfaces of the outer clothing.

In this invention, surfaces of the required reflectivity could be used on outer, inner or internal surfaces of protective or other clothing, including underclothing, to achieve the desired overall radiant heat transfer characteristics of any clothing combination.

This invention will now be described by way of example only.

Consider protective clothing and underclothing to be worn in situations where there is a potential for heat stress where: a) the radiant temperature of the clothing surface is higher than that of the environment, ie. heat could be lost to the environment by radiation, or, b) the radiant temperature of the clothing surface is lower than that of the environment, ie. heat could be gained from the environment by radiation.

Consider protective clothing and underclothing to be worn in situations where there is a potential for cold stress where: c) the radiant temperature of the clothing surface is higher than that of the environment, ie. heat could be lost to the environment by radiation, or, d) the radiant temperature of the clothing surface is lower than that of the environment, ie. heat could be gained from the environment by radiation. 940378 In example a) the innermost and outermost surfaces of the outer clothing and of the underclothing would be selected so that all had the highest possible emissivity at the wavelengths generated by the temperatures of interest to maximise heat loss to the environment by radiation.

In example b) the innermost and outermost surfaces of the outer clothing and of the underclothing would be selected so that all had high reflectivities at the wavelengths generated by the temperatures of interest to minimise heat gain from the environment by radiation.

In example c) the innermost and outermost surfaces of the outer clothing and of the underclothing would be selected so that all had high reflectivities at the wavelengths generated by the temperatures of interest to minimise heat loss to the environment by radiation.

In example d) the innermost and outermost surfaces of the outer clothing and of the underclothing would be selected so that all had the highest possible emissivity at the wavelengths generated by the temperatures of interest to maximise heat gain from the environment by radiation.

Additionally, for example d), the outermost surface of the clothing could be designed to be absorbtive at solar radiation wavelengths and reflective at the infra-red wavelenths generated by the surface temperature of the clothing.

The use of such a selective reflection/absorbtion surface would enhance heat gain from the sum while simultaneously minimising heat loss from the clothing to the environment by radiation.

Suitable selective reflective/absorbtive surfaces could be used in any of the examples above to optimise the heat loss or gain characteristics of the clothing as required.

In situations where the need is for highly insulative clothing where the potential for radiant heat transfer is very great, eg. clothing to be worn by firemen or in the extreme cold, the present invention could result in a garment as shown, for illustration only, in Figure 1. 0378 * In this garment the outer clothing consists of three layers, Layer 10 with Surfaces 11 and 12, Layer 13 with Surfaces 14 and 15 and Layer 16 consisting of an open mesh or open or skeleton foam of material of low thermal conductivity. Surfaces 11,12,14 and 15 are highly reflective at the wavelengths generated by the temperatures of interest. The object of Layer 16 is to separate Layers 10 and 13 by a layer of static trapped air which forms an insulating layer while leaving the majority of Surfaces 12 and 14 unobstructed so minimising heat transfer by radiation between these surfaces. Alternatively, if Layer 16 is constructed from a foam which is inherently reflective at the relevant wavelengths, the foam structure could simultaneously form reflective Surfaces 12 and 14. The reflective outermost Surface 11 of Layer 10 minimises heat gain or loss by absorbtion or emission respectively of radiant energy from or to the environment or any outer clothing and the reflective innermost Surface 15 of Layer 13 similarly minimises heat transfer by radiation to or from the body or underclothing.

The protection against high or low temperatures afforded by the above clothing combination could be increased if the outermost and innermost surfaces of any underclothing are also reflective at the relevant wavelengths.

Where it is wished to minimise heat transfer to the underclothing from the wearer's body, the inner surface of the underclothing could be in the form of an open mesh or foam or deep corrugations to reduce the area of fabric in contact with the body so minimising heat transfer by conduction through the fabric and to trap air so forming a low heat conductive path for those areas of the underclothing not in contact with the body. The surface behind the mesh or foam or the surface of the corrugations would be reflective at the wavelengths generated by the temperatures of interest so also minimising heat transfer by radiation between the body and the underclothing.

Where it is wished to maximise heat transfer to the clothing closest to the body, the surface closest to the body would be made smooth to maximise the area of fabric in contact with the body and given a highly absorbtive surface at the wavelengths generated by the temperatures of interest so maximising heat transfer by both conduction and radiation. 940378 ’

Claims (5)

1. IMPROVED PROTECTIVE CLOTHING 1) Protective clothing in which the fabrics of construction or surface coatings thereon on innermost or outermost surfaces are selected to achieve high emissivity where it is intended that heat be lost from or gained to the clothing by radiative processes or high reflectivity where it is intended that heat is neither gained by or lost from the clothing by radiative processes. In every case, the required emissive or reflective characteristics shall be achieved at the ultra-violet, visible light or infra-red wavelengths generated by the temperatures of interest.

2. ) Clothing as in CLAIM 1) above where the clothing can be the outermost, innermost or intermediate clothing layer.

3. ) Underclothing or other clothing closest to the wearer's body in which the mode of construction and fabrics of construction or surface coatings thereon are selected to be highly reflective or absorbtive at the wavelengths generated by the body so minimising or maximising respectively heat transfer to or from the body by radiative processes as required.

4. ) Protective clothing which has an internal structure which ' incorporates unobscured reflective surfaces thus minimising heat transfer through the clothing, i.e. as illustrated in FIGURE 1.

5. ) Protective clothing in which the structure described in CLAIM 4) is generated between the adjacent surfaces of two items of clothing.