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Textiles For Safety | Flame Resistant Protective Clothing | Safety
Textiles in Space | Protective Health Care Garments |
Mechanical/Chemical/Electrical/Radiaton Protective Clothing
which workers are subjected are hazard from thermal nuclear radiation, and chemical hazards from liquids(sprays),gases or dust occurring in sectors such as fertilizers, electroplating ,and the pharmaceutical or petrochemical industry these hazards necessitate the wearing of clothing that is impermeable is resistant to acids and provides tight seal against toxic gases. Micro-organisms or bacteriological hazards requiring anti microbial fabrics.
In addition to this, bulletproof fabrics and other clothing’s for defense personal to protect them form hazards environment in warfare are required. In the last decade, extensive work has been carried out in the number of laboratories to develop protective clothing for both industrial workers and army .
The survey reveals the complexity of the dangers against which protection is required. Safety clothing made from woven knitted and non-woven fabrics has thus been design to suit specific requirements and performance evaluation technique to simulate the work wear conditions have been developed.
Our paper on safety textiles briefly describe the performance requirement as well as the design of specialized fabric to provide protection against thermal/flame, nuclear hazards, chemicals ,pesticides, microorganisms etc
Introduction:
Modern technological developments have brought with them a vast increase in the kinds of hazards to which workers are exposed. The dangers are frequently so specialized that no single type of clothing will be adequate for work outside the normal routine. Some of the hazards to which workers are subjected are: Hazards from 1. Extreme heat & fire
2. Extreme cold
3. Harmful chemicals and gases
4. Bacterial/ vial environment
5. Contamination
6. Ballistic hazards
7. Electrical hazards
8. Radiation hazards
In the last decade, extensive work has been carried out in a number of laboratories to develop protective clothing for both industrial workers and the army. Protective clothing made from the woven, knitted and non-woven fabric has designed to suit specific requirements, and performance evaluation technologies to stimulate the work wear condition have been developed.
Safety and protective textiles refer to garments and other fabric-related items designed to protect the wearer from harsh environmental effects that may result in injury or death. It may be also be necessary to protect the environment from the people as in the case of clean rooms. Safety and protective materials must often with stand the effect of multiple harsh environments.
Flame Resistant Protective Clothing
Protection from the heat flame molten-metal splashes and radiation sources etc, is a prime requirement for both civil and defense application. The condition influencing demand depends upon specific environmental hazards. The degree of protection, the level of comfort, durability of the garments and the aesthetic as well as sociological factors, such as legislation, consumer awareness of possible hazards etc.
Flame resistant fabrics are designed to resist ignition and self extinguishes when ignited source is removal. In general a properly designed flame resistant fabric will prevent the spread of flame when subjected to intensive heat or flame. Resistant to both flame and associated heat transfer through the garments is defined as thermal protection.
High Temperature Textile:
A high temperature textile material is defined as a material that can be used continuously at temperature over 2000C(@ 4000F) with out decomposition and with out losing its major physical properties. Thermal resistance is the ability of the Fibre to remain relatively unchanged when exposed to radiant, conductive and convective heat.Some of the factors to be considered when selecting a high temperature fibre or fabric for a particular application are:
i) The nature of application
ii) Temperature range and heat generation.
iii) Environmental condition.
iv) Special needs (Special test requirements, special coatings etc.)
Classification:
Flame resistant fibres can be divided into two classesI) Inherently flame -retardant fibres.
Eg. Aramid fibres, Modacrylic fibres, Polybenzimidazoles (PBI) fibres, Semi carbon fibres, and Phenolic fibres.
ii) Chemically modified fibres and fabric
Eg. Flame-retardant cotton, wool and synthetic fibres.
Fire fighter Protective Clothing:
A fire fighter oprotective clothing system icludes coat, pants, underwear, helmet, boots, gloves, station wear uniforms, and breathing devices. Protective clothing for structural fire fighting is made of three layers: the outer layer, the vapour barrier and the thermal barrier.
Clothing for Naval & Armed-forces Personnel:
Anti flash hood and gloves made from Kevlar are now being used by the Royal Newzealand Navy. In a U.S. Navy battledress programme, light weight Nomex fire retardant over alls for men working at engineering tasks and performing work in a hot environments on board ship have been introduced.Clothing for Coal Miners:
Indian Jute Industries Research Association (IJIRA) has developed a flame retardant Jute fabric to be used as a brattice cloth for coal miners.
Protection Against Cold
This type of protective clothing is mainly used in the field of skiwear, rainwear, manufacturing clothing and clothing inside cold storage.
a) Water Proof Breathable Fabric:
Lightweight fabric coated with polyvinyl chloride, polyurethane, and other synthetic rubbers have become increasingly popular for cold weather clothing. Although garments manufactured from these fabrics provide exceptional protection against rain and to a less extent, wind penetration, condensation can accumulate on their inner surface. This problem arises because of the water vapor impermeability of the polymer coating. A build up of moisture vapour inside the clothing may there fore cause discomfort.To overcome this problem, breathable polymer coatings are now available that have made possible great improvement in the comfort of this type of clothing. Microporous polytetrafluoroethylene (PTFE) Gore-Tex laminates have been successfully introduced as a breathable fabric.
b) Temperature-Adaptable Fabric:
Specially treated cotton and blended fibre fabric with improved thermal storage and thermal release property has been invented. For this purpose polyethylene glycol has been chemically fixed to cotton under different curing conditions. Such fabric may have potential in cold protective clothing.Some of the commercially available insulation materials on today’s market are given below.
1) Primaloft
2) Drylete
3) Hydrofil
4) Supplex
Liquid and Gas Protection
Fabrics,which are coated or laminated with special films, are suitable for chemical protection involving liquids and gases. They are used in hazardous or toxic material handling. Examples of material for liquid and gas protection are Saranex and Barricade.Protective Health Care Garments
The purpose of protective healthcare garment is to protect healthcare professional from contamination by blood and other infectious liquids. Protective health care textiles include operating and emergency room textiles, barrier products, breathable membranes, surgeon and nurse’s caps and masks, footwear coats etc.
Protective apparels in medical field should be affordable, breathable, comfortable, dependable and effective. Protective material has to be waterproof but breathable, i.e. it must allow transmission of moisture vapour.
Two types of materials are used to satisfy these contradicting demands.
1) Monolithic Membranes
2) Microporous MembranesSome of the commercially available protective health care materials ,
1) Gore-Tex
2) Gore-Lite
3)Courtek-mMechanical Protective Clothing
The mechanical performance of fibers, have hybrid yarns in their interlacing mode convey to the textile material, a personal protective function against different risk such as ballistic, blade cuts, puncture, projection of fragments, knives, slashing. Combined use of high performance material such as glass fiber, HT Polyethylene or steel e.g. anticut gloves.
Ballistic protection of a soldier involves protection of the body and eyes against projectiles with various shape, size and impact velocity.The principle of ballistic protection by cloth armor is to dissipate the energy of the fragments/shrapnel through stretching and breaking the yarns in the many layers of high performance woven fabrics in ballistic vests
Ballistic Protective Clothing
Fibres Used:
High modulus fibres having high strength and low elasticity is used for ballistic protection. Low elasticity prevents intendation of the body and subsequent trauma caused by protective pack after impact.Vest made of ballistic Nylon fabric were used in the past for protection against fragmentation weapons and low velocity small arms. New requirement for protection against more dangerous weapon have lead to the development of high performance fibres and flexible composites.
Today most widely used material for ballistic protection are Aramid ,Ultra high molecular weight polyethylene and liquid crystal polymer based fibres.
The use of hybrids fibre is increasing in ballistic protecting systems. Aramid fibres blended with ultra high molecular weight polyethylene unidirectional cross-plied non-woven material, which is impregnated with matrix; offer the flexibility and control of the fabric and the high performance of composite non-woven material.
Fabrics Used:
- woven fabric
- non-woven fabric
Woven textiles are the most commonly used for ballistic protection. The majority of ballistic fabrics of course are of plain-woven types. Continuous multifilament yarns with the minimum of twist tend to give best results. . One type of non-woven fabric, the needle felt has been used to produce ballistic protective clothing.Safety Textiles in Space
Space suits used by the austronauts during space shuttle missions represents the ultimate protective clothing in existence today they protect the austronauts from heat ,cold , chemical, micrometeoroids and pressure fluctuations among other things , & materials are nomax &Teflon with Kevlar .
Cloths like neoprene coated nylon cloth , Dacron cloths.. etc..Chemical Protective Clothing
The purpose of chemical protective clothing is to isolate the part of the body from direct contact with a hazardous chemical. Main applications of chemical protective clothing are, to protect farmers from pesticides, fire fighters from chemical substances, workers in the chemical industry etc.
Chemical protective clothing may be categorized as encapsulating and non-encapsulating. Encapsulating type covers whole body including repiratory protection equipment. The non-encapsulating system is assembled from separate components and the repiratory apparatus may be worn outside the suit. Encapsulating garments usually provide better chemical protection.
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Non-encapsulating |
Radiation Protection
Protective clothing is used in radioactive environments to prevent the transfer of radioactive materials such as dirt containing ratio active elements, from directly contaminating the body. These are used for nuclear plant employees, X-ray professionals workers in cancer treatment centers and place subject to ionizing radiation.
Electrical Protective Clothing There are mainly two types of protection from electrical hazards. Electromagnetic protection and Electro static protection
Electromagnetic Protection:
Utility workers that work close to power line and electrical equipment may be exposed to electrical shocks and acute flammability hazards, conductive protective clothing is necessary for people who work in the vicinity of very high voltage equipment. In addition to conductivity, these garments must be flame resistant, wear resistant and comfortable.Conductive protective materials are made of closely weaving metal and natural or synthetic fibres. A typical protective fabric is woven from spun yarns containing a mixture of fire retardant textile fibres and stainless steel fibres (8-12, microns). It was proved that Faraday’s suit made of fabric with 25% stainless steel fibre/75% wool blend or 25% stainless steel fibre / 75% aramid fibre can be effective at voltages up to 400 kv. These types of garment cannot protect the individual if there is direct contact with high voltage line.
Electro Static Protection:
Static electricity is an electricity at rest that is generated by the transfer of electrons. The human body can be considered as a capacitor, may get electrostatically charged .The body transfers its charge to metallic object up on contact, thus creating electrostatic discharge. This discharge can damage on electronic part, and cause an explosion in a hazardous atmosphere, cause a computer glitch through signal minister predation and can cause on involuntary reflex leading to injury.
Using textile fabrics made of intimately blended metal and textile fibres is an effective way to control static build up. Continuous multifilament metal fibres can also be woven in to fabric to control static electricity.
Metal wire content is usually varied between 1% to 5% depending on the hazards level of application. A typical antistatic garment is a blend of 65% polyester 32.5% cotton and 2.5% stainless steel fabric.
Conclusion
Two conflicting requirement that have to be met in protective clothing are:
1) Good performance, which generally requires high mass and bulk.
2) Light and comfortable clothing.
Important design considerations for protective clothing are selection of right kind of fibre. Design specification and final finish so that it will provide good comfort with satisfactory level of performance. So a lot of scopes are there in the field of protective clothing for the development of innovative fabric.References
1) Protective clothing: Textile progress-by Pushpa Bajaj, A.K. Sengupta.
2) Overview of industrial Textiles- By Sabit Adanu
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