Air Monitoring and Sampling Techniques

1
Air Monitoring and Sampling Techniques

• AERT

2
Objectives

• Understand air monitoring and sample techniques
• Knowledge of how the equipment works
• Understand the order of importance for sampling
• Techniques for effective sampling

3
Area Priorities

• Open areas generally receive the lowest priority
  for monitoring due to natural dispersal forces
• Low-lying areas, confined spaces, and containers
  merit a higher monitoring priority
• These areas allow hazardous concentrations of
  substances to persist for extended period of time

4
Sampling Objectives

• Sample with a specific objective in mind such as
  verification of the involved materials
• Help to define the area affected by a plume
• Identify conditions immediately dangerous to life
• Hygene / Continuous Sampling sample a large
  area
• Survey / Direct Sampling sample specific
  locations
• Diffusion Vs Pumps

5
Methods for Sampling

• Sampling should be done in a slow systematic
  method
• 3-levels of air monitoring, high, mid, low
• 1 person samples and monitors while the other
  provides safety
• Monitor leads the way
• Always be able to stop sampling rapidly to
  prevent saturation

6
Order of Importance

• Ph testing
• Radiation
• Oxygen
• Flammability
• Chemical/Toxicity

7
Ph Testing

• Should be tested for first
• Detects acids and bases
• To detect acid or alkali vapors, wet the paper
  then place in vapor
• Is subjective with determining color change
• Can be used in conjunction with a CGI
• Not fool proof Sodium Hypochlorite changes the
  paper to red then bleaches quickly masking a Ph
  of 12

8
Ph

• 1 piece of paper per test
• Possibility of user contamination
• Can spread contaminate
• Can be used in decontamination

9
Radiation Testing

• Second Test
• Both direct and indirect monitors
• Most read Alpha or Beta and Gamma
• Few read all 3
• Can be skipped if no radiation is present
• Time, Distance, Shielding
• Remember your Particle Properties

10
Oxygen Testing

• Third Test
• Can be used in CGI or oxygen meters
• Normal air is 20.9
• Below 19.5 OSHA considers oxygen deficient
• Above 25 considered oxygen enriched
• Work by diffusing oxygen molecules across a
  membrane into a solution
• Must be calibrated to temperature and altitude
  for use
• 1 drop in reading 10,000 ppm of something else
  present

11
Flammability Testing

• Fourth Test
• Measure the concentration of a flammable vapor or
  gas in air
• Results in a percentage of LEL of the calibration
  gas
• Need relative conversion to increase accuracy
• Normal oxygen atmospheres
• Lead vapors, sulfur compounds, silicone
  compounds, acid gases, will all poison the sensor

12
Wheatstone Bridge

• A hot wire filament
• Filament burns gas on its immediate surface
• Meter measures this change as the ratio of
  combustible vapors present, compared to the total
  required to reach the LEL

13
Chemical Testing

• Fifth Test
• Several gas monitors use electromechanical cells
  or metal oxide semiconductors to detect specific
  chemicals
• More accurate than colorimetric tubes
• Only monitor a dozen or so chemicals
• Carbon monoxide, hydrogen sulfide, hydrogen
  cyanide, ammonia, chlorine are a few

14
Oxidizer Testing

• Paper turns gray to black
• Wont tell you which oxidizer is present
• Works in air or liquids

15
Combustible Gas Indicators

• Have come along way
• Most commonly used monitoring tool

• Have ability to read 4 or more gases
• Must be calibrated or bump tested
• Multiple options available
• Increased reliability
• Need Relative Conversion Chart

16
Relative Conversion Chart
17
PID

• Detects a wide range of organic and inorganic
  vapors
• Uses an ultraviolet light to ionize particles
• Reads in ppm or ppb
• 11.7, 10.6, 9.8 eV testing
• Can be used to rule out chemicals
• Stores and converts up to 270 chemicals
• Unknown product use is difficult

18
FID

• Use combustion to ionize airborne contaminates
• Measure organic compounds in ppm
• Do not detect inorganic materials
• Can function as gas chromatographers

19
Colorimetric Tubes

• Use a chemical reaction to produce a color change
• Can be family ( Benzene, Toluene, Xylene)
  specific or product specific
• n-number number of pumps or draws on the tube
• Sampling can vary from 1-30 minutes
• Not highly accurate 25-50 error factors
• Temperatures affect reaction
• Costly with expiration dates

20
Putting it All Together

• Formulate a good plan of action
• Make sure you are monitoring or sampling for the
  right chemicals and reasons
• Allow the monitor to aid in your decisions, not
  make them for you

21
Putting it All Together

• Use the equipment the way it was designed to be
  used
• Take your time, your life may depend on it
• Make sure your actions dont leave you without a
  meter at all

• Know the potential problems before they become
  problems
• Trust your gut

22
The End