Hazmat Book Ch8 Flashcards
What’s degradation?
Physical destruction or decomposition of clothing, material due to exposure of chemicals, use, or ambient conditions like storage and sunlight
What is penetration?
the flow or movement of a hazardous chemical through closures, seams, porous materials, and pinholes or other imperfections in the material. While liquids are most common, solid materials (e.g., asbestos) can also penetrate through protective clothing materials.
When does the potential for penetration generally increase?
In excessively hot or cold temperatures
What is permeation?
It is a process by which a hazardous chemical moves were given material on the molecular level. It differs from penetration in the permeation occurs at the clothing, material self, rather through the opening or gap in the clothing..
What are the 3 steps of permeation?
- Absorption of the chemical into the outer surface of the clothing, generally not detected by the wearer
- Diffusion of the chemical through the clothing material.
- Desorption if the chemical from the inner surface of the clothing material (towards the wearer)
What is the breakthrough time?
The time from the initial chemical attack on the outside of the material until it’s the absorption to its detection inside. usually expressed in minutes or hours.
What’s permeation rate ?
The rate at which the chemical passes through the camera, Cole, protective clothing material and is generally express in micrograms per square centimeter per minute (ur/cm^2/min) for reference purposes .9 µg/ centimeters square/min is equal to approximately 1 drop/ hour
What does cumulative permeation?
Total mass of chemical the permeates during a specific time for when the materials first contacted by the test chemical
What is minimum detectable permeation rate? MDPR
The minimum permission rate that can be detected by the laboratory analytical systems being used for the permeation test
What is system detection limit?SDL
The lowest amount of chemical breakthrough that can be detected by the laboratory analytical system being used for the permeation test. Lower result in lower or earlier breakthrough times.
how does temperature relate to chemical permeation rate?
Most chemical battery tester conducted at ambient temperatures(68° to 70°F/20° to 22.2°C)
Temperature increases mean information rate increases and breakthrough times will shorten
how does thickness relate to permeation rate?
permeation is inversely proportionate to the thickness of the clothing material. in other words doubling its thickness will theoretically cut the permeation rate in half. the breakthrough time will therefore become longer.
how does previous exposure relate to per permeation rate?
once a chemical has begun the diffusion process, it may continue do to diffuse even after the chemical itself has been removed from the outside surface of the material. this is significant when considering the reuse of any protective clothing. decontamination does not ensure the permeation has stopped
what should be considered when evaluating and choosing chemical protective clothing materials
chemical resistance, flammability, strength and durability, overall integrity, flexibility, temperature characteristics, shelf life and decontamination and disposal
what are the two broad categories chemical protective clothing materials are classified in?
limited use materials and reusable garments
