Transcript 1

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
Hazard
Example of
Hazard
Example of
Harm Caused
Thing
Knife
Cut
Substance
Material
Benzene
Asbestos
Leukemia
Mesothelioma
Source of
Energy
Condition
Electricity
Wet floor
Process
Welding
Practice
Hard rock
mining
Shock,
electrocution
Slips, falls
Metal fume
fever
Silicosis
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 nonemergency, 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.
Nuclear-radiation Protection
X-rays Radiation
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.