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52 Cards in this Set
- Front
- Back
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Gases
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Fluids that occupy the entire space of their enclosure. They require increased pressure and decreased temperature for liquification.
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Vapors
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The evaporation products of substances that are also liquid at normal temperatures.
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Aerosol
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Liquid droplets or solid particles dispersed in air.
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Dust
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Solid particles generated by mechanical action (crushing, grinding, impact, etc). Size ranges between 30 micrometers and 0.1 micrometers. Of particular concern for IH's are dusts below 10 micrometers.
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Particulate matter
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Find solid or liquid particles, such as dust, fog, mist, smoke, or sprays.
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Fumes
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Fine particles formed from solid materials by evaporation, condensation, and gas phase molecular reactions. Size range is 1 micrometer to less than 0.01 micrometers.
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Smokes and soot
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Products of incomplete combustion of organic materials and are characterized by optical density. Size is usually less than 0.5 micrometers.
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Fibers
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Particulate with an aspect ratio (length to width) of 3:1 or greater.
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Breathing zone
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Hemisphere in front of the shoulders with a radius of 6-9 in.
Chap 16, Plog |
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Concentration
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mass of contaminant collected/volume of air passed through collection device.
Chap 16, Plog |
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Area air sample uses
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-Evaluate background concentrations
-locate sources of exposure. -evaluate effectiveness of control measures. Chap 16, Plog |
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True or false?
Gases and vapors behave similarily |
True
Chap 16, Plog |
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Name the parts of a sampling train
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Five basic components:
- air inlet orifice - a collection device - an airflow meter - a flow-rate control valve - a suction pump Chap 16, Plog |
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What units are airflows measured in?
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L or cc/m
Chap 16, Plog |
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What is an example of a chemical that may exist as both a gas or vapor and a solid particle at the same time?
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Polyaromatic hydrocarbons
Chap 16, Plog |
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What are the advantages of grab sampling?
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-inexpensive
-simple to use -normally collects 100% of the chemical Chap 16, Plog |
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What are some of the disadvantages of grab sampling?
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- Usually cannot be used to sample reactive gases such as hydrogen sulfide, nitrogen dioxide, and sulfer dioxide unless the samples are analyzed immediately.
- Reactive gases can react with atmospheric dust particles, other gases, moisture, container sealant compounds, or the container itself. Chap 16, Plog |
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What is integrated sampling?
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Extraction of a gas or vapor from a sample airstream followed by laboratory analysis.
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What are the extraction techniques normally used in integrated air sampling?
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Absorption
Adsorption |
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Absorption
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In air sampling, the capture of a gas or vapor accomplished by passing an airstream containing the gas or vapor through a liquid.
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Adsorption
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The condensation of gases, liquids, or dissolved substances on the surfaces of solids.
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True or false?
Acids are highly soluble in water. |
True
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What is breakthrough?
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the mass of a collected gas or vapor in the backup section is greater than 10% of the mass in the front section.
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What are silica gel tubes used for?
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sample for gases and vapors that cannot be efficiently collected or extracted from activated charcoal.
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What is diffusion?
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the passage of molecules through a semipermeable barrier.
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What are NIOSH accuracy requirements?
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+- 25% for 95% of samples tested between .5 and 2.0 times the EL
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What are examples of dispersed solids?
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dusts, fumes, smoke and fibers
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What are examples of dispersed liquids?
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mists, fogs
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Name sampling techniques for the collection of airborne particulates.
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- filters
-imactors -impingers -elutriators -electrostatic precipitation -thermal precipitation -cyclones |
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What is a cyclone used for?
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Collect particles of respirable dust.
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What is considered to be a respirable particle?
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Particles that are retained in the lung and considered to be of an aerodynamic size below 10 micrometers
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What have cyclones traditionally been used for?
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Sample for mineral dusts containing crystalline silica
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How does an electrostatic precipitator work?
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Uses an electric charge to remove particles for the sampled air.
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When are electrostatic precipitators used?
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- the required sample air volume is large, high collection efficiency is required for very small particles, there is a possibility of filter clogging, or high temp airstreams must be sampled.
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How do inertial impactors work?
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collect particles by impacting them onto a surface.
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What are inertial impactors used for?
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determine particle saze distribution.
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How do impingers work?
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collect particles by impacting them into water.
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When are impingers used?
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When the number of particles must be expressed in millions of particles per cubic foot of air (mppcf).
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What are elutriators used for?
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Used in front of sampling trains to remove coarse particles.
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What are the two types of elutriators?
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horizontal and vertical
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What is the minimum air volume for asbestos clearance sampling?
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1200 L
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What are the airflow ranges of personal air sampling pumps?
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low flow: .5-500 mL/min
high flow: .5-5L/min dual range |
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When are low flow air sampling pumps used?
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solid sorbent tube sampling
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When are high flow air sampling pumps used?
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filter, cyclone and impinger sampling
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Critical orifice
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air sampling - a precisely drilled hole in a metal plate through which the airstream being sampled is directed.
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What is the critical pressure ratio?
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downstream pressure (p2)/upstream pressure (p1).
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What is the lower limit of detection?
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The smallest amount of of the chemical that the laboratory can detect.
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LOD
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lower limit of detection
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Maximum air sample
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Used to prevent breakthrough. Designed to handle concentrations up to twice the EL
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What are examples of primary standards?
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spirometers and soap bubble meters
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What are examples of secondary standards
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rotameters, wet test meters and dry test meters.
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What are the three different types of combustible gas monitors?
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-catalytic combustible gas sensor
- metal oxide semiconductor (MOS) - thermal conductivity detector |
