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. 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 Combustible Gas Indicators

16. Relative Conversion Chart Calibration Gas GasBeingSampled Acetone Acetylene Butane Hexane* Hydrogen* Methane* Pentane* Propane* Acetone 1.0 1.3 1.0 0.7 1.7 1.7 0.9 1.1 Acetylene 0.8 1.0 0.7 0.6 1.3 1.3 0.7 0.8 Benzene 1.1 1.5 1.1 0.8 1.9 1.9 1.0 1.2 Butane 1.0 1.4 1.0 0.8 1.8 1.7 0.9 1.1 Ethane 0.8 1.0 0.8 0.6 1.3 1.3 0.7 0.8 Ethanol 0.9 1.1 0.8 0.6 1.5 1.5 0.8 0.9 Ethelene 0.8 1.1 0.8 0.6 1.4 1.3 0.7 0.9 Hexane 1.4 1.8 1.3 1.0 2.4 2.3 1.2 1.4 Hydrogen 0.6 0.8 0.6 0.4 1.0 1.0 0.5 0.6 Isopropanol 1.2 1.5 1.1 0.9 2.0 1.9 1.0 1.2 Methane 0.6 0.8 0.6 0.4 1.0 1.0 0.5 0.6 Methanol 0.6 0.8 0.6 0.5 1.1 1.1 0.6 0.7 Pentane 1.2 1.5 1.1 0.9 2.0 1.9 1.0 1.2 Propane 1.0 1.2 0.9 0.7 1.6 1.6 0.8 1.0 Styrene 1.3 1.7 1.3 1.0 2.2 2.2 1.1 1.4 Tolulene 1.3 1.6 1.2 0.9 2.1 2.1 1.1 1.3 Xylene 1.5 2.0 1.5 1.1 2.6 2.5 1.3 1.6 JP-4 1.2 JP-5 0.9 JP-8 1.5

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. Use the equipment the way it was designed to be used Take your time, your life may depend on it Make sure your actions don’t leave you without a meter at all Know the potential problems before they become problems Trust your gut Putting it All Together

22. The End