Chemgard Infrared Gas
Monitor
TM
EVERY LIFE HAS A PURPOSE…
Chemgard Overview
 What is Photoacoustic Infrared and how does it
compare with other technologies:
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Review of traditional IR
PIR Theory –What happens when light meets sound?
Comparison w/ traditional IR
Electrochemical Sensors
Flame Ionization Detectors
Gas Chromatography
Solid State Sensors
 Chemgard Markets & Applications
Photoacoustic Infrared Gas Detection Technology
 To better understand the advantages of Photoacoustic Infrared
Technology, we will briefly compare it to the older, more commonly
used Absorptive Infrared Technology.
 How Does It Differ?
Infrared Detection Methodology
 Both absorptive and photoacoustic techniques
utilize infrared energy of a selective wavelength.
 Majority of gases absorb infrared energy of
various wavelengths.
 The wavelength selected for use in detection is
determined by the gas in use and its specific
characteristics.
Infrared Technology
 Red is representative
of a typical gas
absorption
characteristic.
 Yellow is an infrared
wavelength used to
detect this specific
gas.
Absorptive Technique
 All absorptive infrared detection methods differ from
manufacturer-to-manufacturer. However, the basic
principal remains the same.
 Sample and Reference measurements must be taken.
 The Sample cell is exposed to the gas to be detected.
 The Reference cell is either isolated from the gas to be detected
or infrared energy outside the absorptive wavelength
characteristics of the gas to be detected is used.
 The two measurements are compared. If they are equal, the
instrument will indicate zero (0).
Absorptive Technique
 When the gas to be detected is present, it
absorbs some portion of the Sample infrared
energy.
 The Reference infrared energy is unaffected by
the gas to be detected.
 The change in ratio of the Sample and
Reference detectors is the actual concentration
of gas present.
Photoacoustic Infrared Technology
 Has been in use since the
1960’S
 MSA –10 Years of experience
in PIR gas monitors
 Has replaced many traditional
infrared analyzers as well as
other sensing technologies
Advanced Technology
Photoacoustic Infrared sensing technology differs
from all other available detection techniques on
the market.
 It has Two distinct advantages:
 The ability to sense a leak as low as in the PPB level
for some applications.
 The ability to operate long periods of time without
adjustment or zero drift, a common problem with all
other technologies in use today.
Basic PIR Cell Assembly
Photoacoustic IR Optical Bench
 IR source - wire filament emitting multiple wavelengths of
light
 Chopper (not shown) - used to setup modulation
 Optical filters
 provide sensitivity and selectivity for a given gas
 selected for specific application
 Optical block - volume can be changed for specific
ranges
 Detector-high sensitivity microphone
 Solenoid valves - sample inlet and outlet provide seal
during photoacoustic gas detection
 Heater and thermostat - temperature control critical for
low PPM or PPB detection
Photoacoustic Infrared Technology
 Sample Gas
Enters the Cell…..
Toxic Gas Sensors
Electrochemical Sensors
Flame Ionization Detectors
Gas Chromatographs
Solid State Sensors
Chemical Tape Technology
Technology Comparison
Gas Detection Comparison
Chemgard Applications
 Applications include:
 CO, CO2, cleaning agents,
solvents, heat transfer fluids &
many other common industrial
chemicals
 Photoacoustic Infrared Gas
Detection used in:
 plastics, paint, automotive,
pharmaceutical, semiconductor,
rubber & other general chemical
industries
Some Chemgard Customers
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3M
Air Products
BASF
Chrysler
Dow Chemical Co
Dupont
GE Plastics
Kimberly Clark
LA Municipal Authority
Miller Brewing
Mitsubishi
Praxair
Toshiba
Walt Disney
Xerox
The Chemgard Advantage
The Chemgard Advantage
The Chemgard Advantage
The Chemgard Advantage
Chemgard Industries
Petrochemical Industries
Plastics & Paint Industry
Agricultural Industry
Rubber Industry
Medical & Pharmaceutical Industry
Semiconductor Industry
Automotive Industry
The Chemgard Advantage
 Utilizes Photoacoustic Infrared Gas Detection
Technology
 Can detect a wide range of industrial
compounds
 Detection of Percent, PPM or in some cases
PPB levels
 High Sensitivity and Selectivity to Gas of Interest