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Introduction to Fabric Performan

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					Protection and Safety

        Chapter 14
        Safety Aspects and Protective
        Properties of Textiles
        (Collier & Epps, 1999)
All textiles are protective
      to some extent

          ?!?!
  What is, then, the main
difference between common
textiles and PROTECTIVE
 TEXTILE MATERIALS?
   Protection/Safety Properties

Protection/Safety properties of textile
 materials are those that protect the
 human body from a variety of
 hazardous environments and harmful
 substances
What is HAZARD?
A hazard is any source (event,
conditions, substance) of potential
damage, harm or adverse health effects
on something or someone under
certain circumstances.
Basically, a hazard can cause harm or
adverse effects (to individuals as
health effects or to organizations as
property or equipment losses).
Sometimes a hazard is referred to as
being the actual harm or the health
effect it caused rather than the hazard.
For example, the disease tuberculosis
(TB) might be called a hazard by some
but in general the TB-causing bacteria
would be considered the "hazard" or
"hazardous biological agent".
             What is RISK?


Risk is the chance or probability that a
person will be harmed or experience an
adverse health effect if exposed to a hazard.
It may also apply to situations with property
or equipment loss.
  Protection/Safety Properties

Hazardous Environments
   Chemical
   Thermal (heat, fire, molten metal, and electric
    arc)
   Mechanical (impact and cut/slash/puncture)
   Radiation (nuclear, UV and electromagnetic)
   Biological
   Extreme ambient conditions
EXAMPLES OF HAZARDS AND THEIR EFFECTS
Workplace   Example of    Example of
Hazard      Hazard        Harm Caused
Thing       Knife         Cut
Substance   Benzene       Leukemia
Material    Asbestos      Mesothelioma
Source of                 Shock,
            Electricity
Energy                    electrocution
Condition   Wet floor     Slips, falls
                          Metal fume
Process     Welding
                          fever
            Hard rock
Practice                  Silicosis
            mining
              Protective Clothing
Personal Protective Clothing is designed to
 extend people’s physical and physiological
 limitations in response to environmental and
 hazardous conditions.
Selection Criteria:
      Protection and safety
      Comfort and functional fit
      Durability
      Functional design details
      Appearance
      Maintenance
      Cost
 Protection From Thermal Hazards
The primary function of thermal protective
 clothing is to minimize or eliminate
 physical harm as a result of fire or exposure
 to hot surfaces, molten metal splashes,
 electric arc explosions, etc.
The performance of thermal protective
 clothing depends on its ability to insulate
 and to maintain structural integrity when
 exposed to high heat.
Materials for Thermal Protection
   Inherent thermal-stable fibers:
     •   Aramid (Nomex®, Kevlar®, Kermel®)
     •   Polybenzimidazole (PBI)
     •   Carbon
     •   Novoloid
     •   Sulfar
     •   Polyphenylene sulfide (PPS)
   Fire-retardant (FR) finished fibers:
     •   Cotton
     •   Wool
     •   Rayon
     •   polyester
 Factors Affecting Fire/Heat Protection
    Burning behavior (thermal resistance)
    Fabric structure
    Thermal inertia (TI)
   TI = density x heat capacity x thermal conductivity

 Guidelines to Ensure Maximum Effectiveness
    Anything worn over protective clothing should be made
     of FR material, specially the outermost garment or layer
    Avoid undergarments such as nylon or polyester/cotton
     blends that can melt against the skin and increase the
     severity of burn injury
    Wear controlled loose-fitting clothing to increase the
     insulating effect of air between clothing layers
Methods of Testing Heat/Fire Protection
   Ignition Resistance and Flammability
     •   Resistance of textile materials to burn
     •   Tendency of textile materials to burn
     •   Flame spread properties
     •   Ease of ignition
   Limiting Oxygen Index
   Heat Protective Properties
    Thermal Protective Performance (TPP) or Exposure
    Energy to Thermal End Point is the thermal energy
    input to a fabric specimen that is required to result in a
    heat transfer through the specimen sufficient to cause a
    second-degree burn in human tissue
 Protection From Chemical Hazards
Workers need to be protected from a wide range
 of hazardous chemical substances, such as
 pesticides, in the form of solid, liquids, or gases.
Effectiveness as barrier against a specific
 chemical, the style and construction, comfort
 factor, mode of use, and cost have an impact on
 the selection of CPC.
Polymer materials used in CPC:
    Tyvek®
    Saranex® (Saran-laminated Tyvek®)
    Teflon®
Permeation Testing
   Permeation of a liquid or vapor through
    protective clothing material, involves three
    steps:
     • The sorption of the chemical at the outside
       surface of the CPC material
     • The diffusion of the chemical through the CPC
       material
     • The desorption of the chemical from the inside
       surface of the CPC
Factors Affecting Permeation Assessment
     Temperature
     Material Thickness
     Solubility Parameter
     Multi-component Liquids
     Persistent Permeation
     Design and Construction of Protective Clothing
Performance Standards for CPC
   NFPA 1991, Standard on vapor protective suits for
    hazardous chemical emergencies
   NFPA 1992, Standard on liquid splash protective suits
    for hazardous chemical emergencies
   NFPA 1993, Standard on protective suits for non-
    emergency, non-flammable hazardous chemical
    operations
 Protection From Mechanical Hazards
Impact Protection
   Impact is defined as a violent contact or collision.
    During the impact event, three actions result from the
    application of forces on impact:
     • Tension
     • Shear
     • Compression
   In order to design protective body coverings, it is
    important to understand the factors in impact on the
    human body that may lead to injury. Critical conditions
    for body protection:
     •   Pressure
     •   Gradual deceleration
     •   Momentum
     •   Elasticity
    The most basic objective of impact protective
     equipment is that prevents penetration of the body by
     an impacting object.
    Age, gender, build up, general health, and physical and
     psychological condition on an individual affect body
     tolerance to a specific injury.

Material for Impact Protection
      Elastic solid foams
      Fiber-reinforced resins
      High-performance polyethylene
      Para-aramid (Kevlar®)
      Light-weight metals
      Ceramics
Factors Affecting Impact Protection
      Material content
      Fabric structure
      Tensile, shear and compression strength
      Resistance to extreme temperatures
      Fabric stiffness

Testing Impact Protection
    Ballistic tests (V50 ballistic limit)
    ASTM Guide F2053-00 Standard Guide for
     Documenting the Results of Airborne Particle
     Penetration Testing of Protective Clothing Materials.
Cut/Slash/Puncture Protection

   Protection against mechanical aggressors is based on
    the same principles as protection from larger scale
    impacts.
   Materials that protect from cut, slash or puncture either
    have a strong, solid surface that repels the aggressor
    (sending its kinetic energy off in another direction) or
    are composed in a way that allows some sort of energy
    exchange to take place.
   Materials used solely for cut resistance do not have to
    provide impact protection but need to resist cutting
Materials Used for Cut/Slash/Puncture Protection
      Cotton
      Leather
      Nylon
      Polyester
      Carbon fiber
      High-performance polyethylene
      Para-aramid (Kevlar®)
Common Protecting Products
      Cut-resistant gloves
      Protective sweaters
      Medical glove liners
      Chain saw cut protection
Testing Cut/Slash/Puncture Protection (ASTM)
   F1342-91(1996)e2 Standard Test Method for Protective
    Clothing Material Resistance to Puncture
   F1414-99 Standard Test Method for Measurement of
    Cut Resistance to Chain Saw in Lower Body (Legs)
    Protective Clothing
   F1458-98 Standard Test Method for Measurement of
    Cut Resistance to Chain Saw of Foot Protective
    Devices
   F1790-97 Standard Test Method for Measuring Cut
    Resistance of Materials Used in Protective Clothing
   F1818-97 Standard Specification for Foot Protection
    for Chain Saw Users
   F1897-98 Standard Specification for Leg Protection for
    Chain Saw Users
  Cut Protection
Performance Tester
Protection From Biological Hazards
Biological hazards involve living organisms that
 can reproduce in supportive environments. They
 are particular dangerous because small amounts
 can contaminate a community once they have
 entered just one “host” and subsequently been
 passed to others while they continue to grow.
Biological hazardous substances may reach and
 eventually harm the body by four different routes:
      Direct contact
      Breathing in
      Ingestion
      Injection
Materials for Biological Protection
    Physical Methods of Imparting Protection
      • Three-layered composite non-wovens (spun-bonded/
        melt blown/spun-bonded)made of polypropylene or
        polyester/pulp.
      • Polyethylene-coated wet-laid non-wovens
      • Melt blown microfiber filter media for masks
    Chemical Methods of Imparting Protection
      • Antimicrobial-coated woven and non-woven
        materials
      • Liquid-repellent fabrics and membranes
                Mechanical Pressure Tester1

1 ASTM   F23.40.04, Draft test method for the resistance of materials
used in protective clothing to penetration by synthetic blood.
Testing Biological Protection (ASTM)
   F1670-98 Standard Test Method for Resistance of
    Materials Used in Protective Clothing to Penetration
    by Synthetic Blood
   F1671-97b Standard Test Method for Resistance of
    Materials Used in Protective Clothing to Penetration
    by Blood-Borne Pathogens Using Phi-X174
    Bacteriophage Penetration as a Test System
   F1819-98 Standard Test Method for Resistance of
    Materials Used in Protective Clothing to Penetration
    by Synthetic Blood Using a Mechanical Pressure
    Technique
   F1862-00a Standard Test Method for Resistance of
    Medical Face Masks to Penetration by Synthetic Blood
    (Horizontal Projection of Fixed Volume at a Known
    Velocity)
 Protection From Radiation Hazards
Protection Against Nuclear Radiation
   The effects of large nuclear radiation can have severe,
    often fatal, consequences to human beings for short and
    long terms.
   Protective clothing designers must understand how
    radiation affects the body to determine the types and
    levels of protection needed.
   Types of radiation:
     •   X rays
     •   Ionizing radiation
     •   Alpha, beta and gamma radiation
     •   Microwaves
   There is protective clothing against alpha and beta
    radiation, but not for gamma radiation.
Clothing for Nuclear Radiation Protection
    Protective clothing for nuclear power workers
     generally takes the form of completely encompassing
     coverall with integrated gloves, boots and hood.
    These anti-contamination suits are made of
     impermeable vinyl to closely woven materials such as
     cotton.
Clothing for X-Rays Radiation Protection
    The material most commonly used in X-ray protective
     clothing is lead-impregnated vinyl. It is also possible to
     use antimony instead of lead because it is about four
     times lighter than lead, but antimony is more expensive.
    The protection offered by radiation-protective materials
     is expressed in millimeters of lead equivalency.
                               X-rays Radiation
Nuclear-radiation Protection      Protection
Protection Against UV Radiation
   Ultraviolet radiation (UVR), from the sun or artificial
    sources, is associated with problems such as
    carcinogensis, cataracts, sunburns, and photo-aging.
   UV-A radiation (320 to 400 nm) causes little visible
    reaction on the skin, but can decrease the
    immunological response of skin cells.
   UV-B radiation (290-320 nm) can cause sunburn and
    may be also responsible for the development of skin
    cancer.
   Factors affecting UV protection
     • Fabric cover factor
     • Fiber content
     • UV-absorbent finishes
Testing UVR Protection
   Sun Protection Factor (SPF)
      % UVR transmission = 100 - % cover factor
      SPF = 100 / % UVR transmission
      SPF = 100 / 100 - % cover factor
   Total UV transmission evaluated as a function of
    wavelength measured by a spectrophotometer.
   In order to calculate the SPF value from the
    transmitted radiation, two additional spectral factors
    must be taken into account: The relative strength of the
    solar radiation as a function of wavelength and the
    relative erythermal response (reddening) of the skin to
    each given wavelength of light.

				
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posted:4/3/2010
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