Chapter 29
Product Control and Air
Monitoring
Introduction
• Product control techniques can
provide quick reduction in damage
• Reduction of surface area reduces
danger to responders and
community
• Use of air monitoring devices is
becoming more commonplace
• To ensure firefighter safety, basic air
monitoring must be accomplished
29.2
Defensive Operations
• According to NFPA, three large tasks
fit into operations-level tactical
response:
– Basic air monitoring
– Containment
– Confinement
• Type and level of PPE for each task
will vary with chemical involved
29.3
Absorption
• First responders often asked to clean
up spilled material
• Absorption commonly used for fuel
and oil products
• Know type of absorption material
carried on apparatus
• Filter fences hold absorbent material
29.4
A screen fence can be used to collect the absorbent
material floating on the water after the absorbent has
collected the spilled material. The water flows through the
fence below the absorbent.
29.5
Diking and Damming
• Quantity of material spilled determines
extent of diking and damming operations
performed
• Use earth, sand, or rocks for dikes or
dams
• Local or state highway departments are
a good source for materials
• Do not set barrier too close to spill
• Two basic dams
– Overflow
– Underflow
29.6
The overflow dam allows the clean water to flow over the dam
and collects the spilled material at the base of the dam. The
underflow dam collects the spilled material on top and allows the
water to flow through the bottom of the dam.
29.7
Overflow dam.
Underflow dam.
29.8
Diverting
• Almost anything can be used
• Keep a running spill from entering a
storm drain
• Can be used for spills on water
• Dig trench alongside waterway to
collect spilled material
29.9
Retention
• Most common method is digging a
hole
• Creating a large enough containment
area is paramount to success
• If one large area cannot be dug, dig
several smaller holes in a row
29.10
Building a retention area is a good method for holding released
products. Retention areas can be dug from existing earth or created
with truckloads of sand or dirt. Small holding areas can be hand dug,
but for larger spills heavy equipment is required.
29.11
Dilution
• Not always the solution for pollution
• Flushing of material into waterway is
not acceptable
• Dilution may work when combined
with other containment tactics
29.12
Vapor Dispersion
• Material that is being released must
be water soluble
• Not recommended unless a life
threat exists
• Water at natural gas leaks further
complicates repair
• Use of water can also result in
creation of another substance
29.13
Vapor Suppression
• With use of firefighting foam
• Type of material spilled dictates the
type of foam
• Before application of foam,
responders should ensure material
is contained
29.14
Remote Shutoffs
• Not usually a tactic used by first
responders
• Remote shutoffs could be operated
by first responders
• Usually well marked as emergency
shutoffs
29.15
Air Monitoring at the First
Responder Operations Level
• Air monitoring is one of the most
important tasks to accomplish
– pH detection
– Combustible gas detector
– Photoionization detector (PID)
• Most fire service responders have
reasonable understanding of
combustible gas indicators
29.16
First responders commonly use devices that detect the
presence of flammable gases, carbon monoxide, and hydrogen
sulfide and determine the oxygen content. This detector also
detects the presence of common toxic vapors.
29.17
Regulations and Standards
• HAZWOPER regulation does not
provide a lot of specific requirements
for air monitoring
• NFPA 472 is fairly generic
• Important for first responders to
understand how monitors work
29.18
Air Monitor Configurations
• Most departments purchase a
three-, four-, or five-gas instrument
• Also called a multi-gas detector
• Inexpensive compared to other
detection devices used by
hazardous material team
• Sensors need replacement
• Problems created by lack of
maintenance and adequate training
29.19
Meter Terminology
• Responder must understand basic
terminology that is generic to all
monitors
–
–
–
–
–
Bump test
Calibration
Reaction time
Recovery time
Relative response
29.20
Bump Test
• Exposes a monitor to known gases,
allowing the monitor to go into alarm
mode
• Most manufacturers provide bump
gas cylinders
• Used to ensure that alarms function
and instrument is reading
29.21
Calibration
• Determine if monitor responds
accurately to exposure to a known
quantity of gas
• When new sensors are installed,
monitor should be calibrated
• Regularity of calibration is subject to
great debate
29.22
Calibration involves exposing the instrument on the
right to a known quantity of gases to ensure that it is
reading the gases correctly. This kit calibrates the
monitor with a variety of gases.
29.23
Reaction Time
• All monitors have a lag time, better
known as reaction time
• Monitors operating without a pump
are in diffusion mode
– Will have 15- to 30-second lag time
• Monitors operating with a pump have
reaction time of 7 to 30 seconds
• WMD detection devices may take up
to 90 seconds to react
29.24
Recovery Time
• Recovery time is the amount of time it
takes the monitor to clear itself of air
sample
• Affected by:
– Chemical and physical properties of sample
– Amount of sampling hose
– Amount absorbed by monitor
• Sometimes instrument must be taken out
of environment and restarted
• Reaction time affects overall recovery
time
29.25
Relative Response
• When gas monitor is purchased, it is
set to read a specific type of gas
• Relative response describes the way
monitor reacts to gas other than the
one it was calibrated for
• Each person operating an air monitor
must have a basic knowledge of
relative response
• Actual LEL reading = Detector
reading  Response curve factor
29.26
Correction Factors (Calibrated to Pentane)a
29.27
Oxygen Monitors
• Oxygen: one of most important things to
sample
• Normal air contains 20.9 percent oxygen
– Below 19.5 considered a health risk
– Above 23.5 considered a fire risk
• Oxygen-enriched atmospheres result from
a chemical reaction involving oxidizers
• Temperature below 0°F can permanently
damage the sensor
• Requires calibration at pressure of sample
29.28
Flammable Gas Indicators
• All of these types of sensors work, some
better than others in different situations
– Catalytic bead sensor
– Metal oxide sensor
– Infrared sensor
• Most FGIs read up to the LEL of the gas
– Longer the exposure is above the LEL, the
quicker it loses its life
• Any flammable gas will cause a reaction in
the sensor
29.29
Examples of flammable gas indicators: catalytic bead,
metal oxide, and infrared.
29.30
Toxic Gas Monitors
• Sensors commonly used in multi-gas
monitors
– Also usually used to measure CO and H2S
• Toxic sensors are available for a variety of
gases
• Most toxic sensors are electrochemical
sensors
– Have electrodes and a chemical mixture sealed
in a sensor housing
• Gas passes over the sensor, causing
chemical reaction, creating electrical charge
• Toxic sensors display parts per million
29.31
Tactical Use of Multi-Gas
Detection Devices
• MOS sensors react quickly and detect low
levels of flammable gas
– Not accurate, fluctuate considerably
– Detect water vapor and give erroneous
readings
• Catalytic bead and infrared both are
accurate
• Most flammable gas detectors only read
methane accurately
• When LEL sensor alarms at 10 percent
level for an unidentified material, they
should retreat
29.32
Other Detectors
• Following detectors are used by a
hazardous materials team, but
should be understood by first
responder
–
–
–
–
–
Photoionization detectors
Radiation pagers
Colorimetric tubes
Chip measurement system
Air monitoring equipment
29.33
Using Air Monitoring Equipment
• Ensure battery level and bump test
the instrument
• Understand what the flammable gas
sensor detects and what it does not
detect
• The oxygen sensor indicates the level
of oxygen
• Understand the alarm levels for the
instrument being used
29.34
Carbon Monoxide Incidents
• 40,000 people treated for carbon monoxide
poisoning each year
• SCBA functioning when rescuing residents
• On arrival, fire service monitors will not read
CO even if present in dangerous
concentrations
• Brand and type of CO detector determines
performance
– Biomimetic
– Metal oxide
– Electrochemical
29.35
Biomimetic
• Gel-like material
• Prone to false alarms
• May need 24 to 48 hours to clear
itself
29.36
Metal Oxide
• Same type of sensor used in
combustible gas detector
• Has cross sensitivities and reacts to
other gases
• Responders could be walking into a
flammable atmosphere
• Requires a lot of energy, provides a
digital readout
• Clears in less than 24 hours
29.37
Electrochemical
• Also referred to as an instant detection and
response sensor
• Two charged poles in a chemical slurry
– CO causes a chemical reaction
– Changes the resistance within the housing
• Provides an instant reading of CO
– Internal mechanism that checks the sensor
• Provides the best sensing capability
29.38
Lessons Learned
• Defensive product control is a key
component
• First responders have equipment
necessary to handle these tasks
• Limiting spill will mitigate incident
sooner
• First responders are becoming more
involved with air monitoring
• Understanding action levels are an
important consideration for safety
29.39