Air Monitoring at SCFD #7

1. Air Monitoring at SCFD #7 Know your environment!

2. Objectives • Review the use of the MSA Altair 4x • Review basic air monitoring techniques and strategy

3. Terminology • Hydrogen Sulfide • Carbon Monoxide • LEL/UEL • TWA PEL • STEL or C • IDLH • NIOSH

4. Purpose of Air Monitoring • Rescue/Recon • Determine size and location of control zones • Develop an initial isolation zoneor an exclusionary zone • Identification of the substance and quantify • Determine exposure/contamination • Determined when the incident is safe

5. Monitoring Strategy Monitoring Priorities Determine IDLH atmospheres or values that exceed the STEL Flammability Radiation Oxygen Presence of a contaminant • Always start your instrument in fresh air • Have an idea of what readings you should expect • The absence of a positive response does not necessarily mean that contaminants are not present • Never assume only one hazard is present • Establish actions based on readings

6. Basic Air Monitoring Technique • Go slow, look at the display • Sample high, medium and low • Don’t sample haphazardly. Prior to entry, determine sampling priorities • Know the limitations of the monitor • When reporting the results, read each result separately • Example: • LEL 0% • Oxygen 20.8% • CO 0 ppm • H2S 0 ppm • You should never report a reading of “zero”or “nothing found”

7. SCFD #7 Air Monitoring Devices • MSA Altair4x

8. Air Monitor or“4-Gas Monitor” • Oxygen Concentration (in percent O2) • Flammability (in percentage of lower explosive limit) • Carbon Monoxide Concentration (in parts per million [ppm]) • Hydrogen Sulfide Concentration (also in ppm)

9. Oxygen The percentage of oxygen concentration shown by the four gas meter is a valuable piece of information that does triple duty for us, as it displays not only the possible existence of an oxygen-deficient atmosphere, but also the possibility of an oxygen-enriched atmosphere or possible contamination of the atmosphere by other products. However-for a substance to displace 1% of the oxygen it take 10,000 ppm, or even to displace 0.1% it would take 1000 ppm

10. Oxygen • Normal Oxygen Level 20.8% • Low Oxygen 19.5% • Oxygen Enriched 23.5%

11. LEL • The four gas meter displays flammability in terms of the percentage of lower explosive limit (LEL). In simple terms, our percentage of LEL tells us how close we are getting to the point at which a substance is guaranteed to ignite or explode if an ignition source is present.

12. Correction Factors • One concept of the Combustible Gas Indicator (CGI) that is often overlooked is that the CGI exhibits what is termed a “relative response” when monitoring any substance other than that which the sensor is calibrated to. • For example, if your CGI is calibrated to methane and you are monitoring another substance, the number indicated on the CGI is not the percentage of LEL, but is rather meter units. • Meter units are simply a non-dimensional number that must be multiplied by a correction factor (CF) to determine the actual percentage of LEL. • Note: The largest correction factor for a monitor calibrated to methane is 3.4

13. LEL Correction Factors • Acetone 1.7 • Acetylene 1.3 • Benzene 1.9 • Butane 1.7 • Ethane 1.3 • Ethanol 1.5 • Ethylene 1.3 • Hexane 2.3 • Isopropanol 1.9 • Methane 1 • Methanol 1.1

14. LEL Correction Factors • Pentane 1.9 • Propane 1.62 • Styrene 2.2 • Toluene 2.1 • Xylene 2.5

15. How do you use a Correction Factor? • Know what the substance is that you are monitoring for • Locate the Correction Factor • Multiply the actual reading on the device times the correction factor • Example: • Monitoring for Pentane (CF = 1.9) • LEL sensor reading = 9% • 9 x 1.9 = 17.1% • (How many ppm is 17.1% in air)

16. Carbon Monoxide • We commonly respond on CO alarms due to home CO detector. • We can use our 4-gas monitor to determine if it is a false alarm or if CO is actually present in the residence. • Low setting 35 ppm • High Setting 100ppm • IDLH 1200 ppm • TWA 35 ppm • STEL 200 ppm

17. At what PPM of CO will we advise a homeowner that it is safe to occupy their residence?

18. Hydrogen Sulfide The final sensor in our four sensor suite is the H2S sensor. H2S sensing capabilities are often times utilized in confined space or below grade settings, as the existence of hydrogen sulfide (better known as sewer gas) in such settings in sufficient concentrations can be fatal to personnel making entry without performing sufficient air monitoring.

19. Hydrogen Sulfide Levels • Low Setting 10 ppm • High Setting 20 ppm • IDLH 100 ppm • TWA 10 ppm • STEL 50 ppm

20. Daily check • At the beginning of each day your four gas monitor should be checked for proper operation. To do this you must: • Turn the monitor on • Check the battery level and charge if necessary • Ensure the monitor is working • Zero sensors • Turn monitor off • Also-the monitor should be charged on a weekly apparatus check

21. SCFD #7 Procedure Review • Review procedures 3-29 and 3-31 for more air monitoring recommendations • Never attempt to monitor a known hazardous environment in training (ie, gasoline vapors, vehicle exhaust, etc.)

22. Thank you for your time • If you have any questions or concerns regarding your four gas monitor please contact a HazMat technician or the Training Division.