04 Tactical Air Monitoring Flashcards
What is the most important training step you can take to size-up life-and-death situations?
Knowing your monitor and its strengths and limitations
The second most important consideration for your air monitoring equipment is:
calibration
Calibration
when you show the instrument a known concentration of gas and tell it to adjust its measurements to that known concentration or number.
Bump Testing
When the meter is shown a known concentration and reacts properly to it.
Five main types of gas detectors:
- Laser
- Wheatstone Bridge
- Metal Oxide Sensor
- Catalytic Bead
- Electrochemical
Laser
Range: 100’
Gas Detection: 5-50,000 ppm range
Can detect gas through glass
Limitations of Laser
- LEL risk evaluation - indicates presence and volume but not concentration
- Bright light - might be hard to see green spotter light
- Only works for methane
- Reflective windows - Tinted or mirrored windows mess it up
- Shades, blinds, and drapes - Prevent laser from penetrating deep into building
Advantages of Laser
- Speed
- Critical Information -Is there gas? a lot or a little?
- Distance - long range
- Locked buildings - effective against most windows
- Training - easy
- Versatility - can be used to find source of leak
- Flooded building
Wheatstone Bridge
Older Tech
Metal Oxide Sensor
Strength: ability to detect very low levels of combustible gases almost instantly.
Advantages: Almost instant ability to detect and provide data; Ability to detect at much lower levels (0-990 ppm) than a catalytic bead or Wheatstone bridge.
Catalytic Bead Sensor
Advantages: more accurate than most and can read 0-100% LEL.
Electrochemical Sensors
Usually included in 4-gas meters
Response Time (t90)
The time for a sensor to reach 90% of its final stable reading.
What is likely the most important sensor and why?
The oxygen sensor.
A reduced oxygen level may negatively affect your combustible gas reading.
Chlorine Gas and Hydrogen Sulfide Immediately Dangerous to Life or Health (IDLH) level is
10 ppm
