Protective Clothing.pdf

7/27/2019 Protective Clothing.pdf

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Dr. V. K. Kothari

Department of Textile Technology, IIT, Delhi

Schematic of classifications of Protective Textiles


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Flame retardanto Kermel and Kermel / Viscose fabrics for

flight suits, station wear and turnout gear.o Nomex for military applications

o Molten Aluminum splash protective fabric.

o Electrical Arc

Ballistic protectiono p Aramid woven fabric for hard and soft

ballistic applications

Lint free antistatico Continuous filament polyester / carbon fabrics

Medical textileso Systemic and non systemic antibacterial and

antistatic fabrics for surgeons gowns, scrubs and

warm up jackets.

Chemical protectiono Liquid chemical protective fabrics

UV protectiono Fabrics that offer a UPF rating for the wearer.

Industrial work wearo Component fabrics for chain saw protection

o freezer suits

o waterproof clothing

Military textileso Uniforms

o Parachutes


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Materials & Technologies

Processing technologies for specific

protective clothing are different, the main

processes generally include:

Material manufacturing or selection;

Producing fabrics and other related items;

Finishing, and

Clothing engineering.


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Schematic of materials and technologies for

manufacturing protective textiles

Steps in selection of protective clothing materials

Step 1: Assess hazards

Type of hazard(s)

Severity of the hazard

Step 2: Identify relevant standards,

specifications, or guidelines

With well defined performance requirements

Not well defined performance requirements


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Steps in selection of protective clothing materials

Step 3 Screen materials based on protection

performance of fabrics, e.g. Cold climate protection performance

Chemical protection performance

Biological protection performance

Flame and thermal protection performance

Mechanical protection performance

Step 4 Select materials based on other majorfactors

Job performance

Comfort Cost

Durability

Use, care & maintenance

AGENDA

Look at some aspects related to:

Extreme old protection

Chemical & Biological protection

Radiation protection

Electrical protection

Heat & Flame protection

Mechanical protection High visibility Protection


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EXTREME COLD PROTECTIVE CLOTHING

Hazards of Extreme Cold Climate

Increased incidence of Arthritis,Rheumatism and Bronchitis

Cold metal injury

Hypothermia - one of the serious

hazards of cold exposure Frostbite


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Comfort & Survival Factors in

Cold Protective Clothing

1. Physiological Factors

Metabolic heat output

Perspiration rate

2. Environmental Factors

Wind Chill

Relative Humidity or Dampness of theEnvironment

3. Fabric Factors

Thermal insulation

Air permeability

Moisture vapour permeability

4. Design of the Fabric Assembly


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The human heat balance equation

Appropriate protection against cold is provided when the human body is in heat

balance at acceptable levels of body temperatures (for example skin and core

temperatures).

This implies that heat losses are equal to metabolic heat production.

The following equation describes the heat balance.

where S is the rate of change in body heat content,

M is the metabolic heat production,

C is the convective heat exchange,

R is the radiative heat exchange,E is the evaporative heat exchange,

and RES is the respirative/airway heat loss, all in W/m2.

Thermal insulation

Evaporative resistance

Wind resistance

Water resistance

Measurements of clothing performance


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Category of Fibres which provides

Thermal Insulation

A. Heat Insulating

- to entrap as much air as possible.

- Low compressibility and high resilience

- Conventional fibres, hollow fibres & highbulk fibres

B. Heat Absorbing

- to maintain the microclimate inside theclothing

- Solar radiation absorbing fibre and fibrescontaining ceramic particles to absorb IRradiation

C. Heat Storing- Phase change materials


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Types of Layer- Combination

Outer layer should provide adequateresistance to wind penetration & shouldbe water vapour permeable

Next-to-skin layer of the garment shouldwick the liquid sweat away from thebody rapidly

Middle layer(s) should provide the maininsulation. Body heat should be

reflected back using a inner reflectivelayer.


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Structural Model of a Cold Weather

Protective Clothing

Laminates with Aluminum Film


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Engineered Fibres

An unique polyester fibre such as Primaloft Air pockets increases the thermal resistance and

help it to resist the passage of water whileallowing body moisture in form of water vapour toescape

Insulation through Incorporation of

Integrated Heating Panels

Light weight, washable heating panelspowered by batteries are laminated inthe fabric


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Smart Polymeric Membranes

Laminated fabrics made frommonolithic breathable membranewhich react to build up of heat andmoisture

As the microclimate temperaturerises, the openings between thepolymer molecules in the membrane

expand, thereby increasing the fabricmoisture permeability. As thetemperature drops the pores in the

Chemical Protection

Chemical Hazard

Affects human based on its characteristics and mode of entry

Chemicals present a variety of hazards such as toxicity,

corrosiveness, flammability, reactivity, and oxygen deficiency

Routes of chemical entry into the human body are oral,

respiratory, and dermal

Dermal exposure considered primary mechanism of chemical

entry through human body


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Chemical Resistant Clothing

It provides an effective barrier between thechemicals used & area of the body to be protected

No single material will protect against all chemicals

Appropriate chemical resistant clothing must demonstrate:

No penetration

No significant degradation

Low permeation rate


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Chemical/Biological (CB) warfare agents and their effects

To design and to fabricate effective CB protective clothing, it is necessary to

have an understanding of the hazardous threats that must be prevented from

reaching the wearer.

CWAs are defined as natural or synthesized chemical substances, whether

gaseous, liquid or solid, which might be employed because of their direct toxic

effects on man, animals and plants.

BWAs are microorganisms (viruses and bacteria) or toxins derived from

living organisms.

They are used to produce death, or incapacitation in humans, animals, or

plants. Typical effects of selected CWAs are listed in Table given in the

next slide.

Chemical and biological protection

Typical effects of toxic chemicals, microorganisms, and toxins


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There are basically four different types of CB Protective Materials.

Figure illustrates the differences in their protective capabilities.

Different types of protective materials

Examples of Chemical Protective Cloth ing

z Three layers outer fabric, sorptive layer and inner layer

Layers of Protective Clothing

Outer shell is water repellent layer protecting from liquid chemicals Sorptive layer is soul of protective clothing absorbing liquid &

air borne chemicals

Inner layer provides comfort to the wearer


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Development of Chemical Protective Clothing

Polyester fabric

Cotton Nonwoven

Activated carbon

Cotton Nonwoven

Cotton fabric

Formed by five layers

Outer shell made of polyester as it has low absorption of 2% &

provides good strength to the fabric and polyester has a good

resistance to lab grade chemicals

Inner layer is made up of cotton fabric as it gives good

absorbency and comfort

Middle layer comprises of activated carbon sandwiched in

cotton nonwoven

Chemical Protective Clothing


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CPC Garment materials

Textiles

Unsupported rubber or plastics

Microporous film basics

Adsorbent-based fabrics

Coated fabrics

Plastic laminates

Combinations

The use of excellent protective materials, effective closures, and

ergonomic survival equipment for an individual will be meaningless

and unproductive without proper garment designs.

There are different garment designs given as follows:

Coverall or one-piece garments

Two-piece garments

Undergarments

Multilayered garments

Closure system, components, and systems

Clothing system designs


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UV exposure and human skin

Effect of UV rays on different types of skin

Radiation Protection

Ultraviolet radiation band

UVA(320 to 400 nm)

UVB(290 to 320 nm)

UVC(200 to 290 nm)

Causes little visiblereaction on skin

but decreaseimmunologicalresponse of skin cells

Responsible for

development ofskin cancers

Totally absorbed by

atmosphere &doesnt reach theearth

Radiation Protection


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Fabric's ability to block UVR dependent on several parameters:

Principal Parameters

Fiber Chemistry Fabric Construction Moisture content Wet Processing History

WeightThicknessPorosity

Dye

Concentration

Fluorescent

Whitening

Agents

UV-absorbers

Textiles as protection from ultraviolet radiation

Schematic representation of a textile as a barrier to UV radiation


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Electrostatic Protection

The term `electrostatic' or `static electricity' refers tothe phenomenon associated with the build up of

electrical charges generated, for example, by contact

and/or rubbing of two objects. Static electricity is

generated by unbalancing the molecular configuration

of relatively non-conductive materials.

Discharge of static electricity

In principle, there are three methods for

neutralizing charges on insulators:

conductance through the bulk of the material

conductance along the surface of the material

the attraction of oppositely charged ions from

the air


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Measurement techniques

There have been two main approaches to assessing theelectrostatic propensity of textile materials.

One is to measure the charge built up on a clothed

person or the electrical capacitance of a body (human-

body model)

The second is to measure some electrostatic

characteristics of textiles (e.g., surface resistivity,

charge decay rate, peak potential, etc.) in small-scaletests.

The most common way to confer anti-static properties on a fabric is to

incorporate conductive fibres/yarns.

Common conductive elements used in

fabrics include carbon, copper, silver,

stainless steel or metallic salts.

The choice of conductive product will

partly depend on the end use and the

required level of static protection.


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Modern ESD-textiles

Many ESD-garments are made of heterogenouscomposite fabrics where a grid or stripes of

conduct ive threads are present inside an

insulating matrix of cotton, polyester or mixtures

of these materials.

The conduct ive threads are more and morefrequently made by composites, i.e. by a mixture

of conductive and insulating fibres.

There are several variations in both fabric andthread s tructures.


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Gore-tex: Antistatic

Source: AVANTEX 2000

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Protective Clothing.pdf