Discussion
Chemical-Protective Clothing and Equipment
Chemical-protective clothing is designed to prevent chemicals from coming in contact with the body and may have varying degrees of resistance. Chemical-protective clothing material is any material or combination of materials used in an item of clothing to isolate parts of the wearer’s body from contact with a hazardous chemical. Chemical resistance is the ability to resist chemical attack. Time, temperature, stress, and reagent are all factors that affect the chemical resistance of materials. Chemical-resistant materials are specifically designed to inhibit or resist the passage of chemicals into and through the material by the processes of penetration, permeation, or degradation.
Penetration is the flow or movement of a hazardous chemical through closures (like zippers), seams, porous materials, pinholes, or other imperfections in the material. Liquids are most likely to penetrate material, but solids (like asbestos) can also penetrate protective clothing materials.
Permeation is the process by which a hazardous chemical moves through a given material on the molecular level. Permeation differs from penetration in that permeation occurs through the material itself rather than through openings in the material.
Degradation is the physical destruction or decomposition of a clothing material due to chemical exposure, general use, or ambient conditions (like storage in sunlight). Degradation may be evidenced by visible signs such as charring, shrinking, swelling, color changes, or dissolving. Materials can also be tested for weight changes, loss of fabric tensile strength, and other properties to measure degradation.
Other performance requirements must be considered when selecting chemical-protective materials. These requirements include chemical resistance, flexibility, abrasion, temperature resistance, shelf life, and sizing criteria.
Chemical-protective clothing can be constructed as a single- or multi-piece garment. A single-piece garment completely encloses the wearer and is known as an encapsulated suit or acid suit. Encapsulated protective clothing offers full body protection from hostile environments and requires the use of air-supplied respiratory protection devices, such as SCBA. A multi-piece garment works with the wearer’s respiratory protection, an attached or detachable hood, gloves, and boots to protect against a specific hazard.
Various materials are used in both encapsulated and non-encapsulated protective clothing. The most common include butyl rubber, Tyvek, Saranex, polyvinyl chloride (PVC), and Vitron, either singly or in multiple layers of several materials.
Special protective chemical clothing is adequate for some chemicals and useless for others; no single material provides satisfactory protection from all chemicals. Protective clothing materials must be compatible with the chemical substances involved and consistent with the manufacturer’s instructions. The manufacturer’s guidelines and recommendations should be consulted for material compatibility information.
Some materials are so caustic or corrosive that they could destroy SCBA after a short exposure. Personnel trained to the operations level should not be operating in encapsulated suits. Operational personnel can wear some non-encapsulated chemical protective clothing while providing support for those entering the hazardous materials area.
Liquid splash-protective clothing consists of several pieces of clothing and equipment that protects the skin and eyes from chemical splashes . It does not provide total body protection from gases or vapors and should not be used for incidents involving liquids that emit vapors known to affect or be absorbed through the skin. Vapor protective clothing must be used when hazardous vapors are present. Vapor-protective clothing traps the fire fighter’s body heat, so fire fighters and support personnel must be aware of the possibility of heat-related emergencies. SCBA or airline hose units must also be used for respiratory protection.
Fire fighters may wear liquid chemical splash-protective clothing over or under structural firefighting clothing in some situations. This provides limited chemical splash and thermal protection. Fire fighters trained to the operational level can wear liquid chemical splash-protective clothing when they are assigned to enter the initial site, to protect decontamination personnel, or to construct isolation barriers such as dikes, diversions, retention areas, or dams.
Questions
The process by which a hazardous chemical moves through closures, seams, or porous materials is:
A. penetration.
B. degradation.
C. permeation.
D. vaporization.
The physical destruction of clothing due to chemical exposure is:
A. penetration.
B. degradation.
C. permeation.
D. vaporization.
