083730400A DCN8130
Teledyne API – Model T400 O
3
Analyzer
39
C
ALIBRATION
(S
PAN
)
G
AS
Span gas is specifically mixed to match the chemical composition of the type of gas
being measured at near full scale of the desired measurement range. Because ozone (O
3
)
quickly breaks down into molecular oxygen (O
2
), this calibration gas cannot be supplied
in precisely calibrated bottles like other gases.
•
If the T400 analyzer is not equipped with the optional internal zero air generator (IZS), an
external O
3
generator capable of supplying accurate O
3
calibration mixtures must be used.
•
Also, some applications, such as EPA monitoring, require multipoint calibration checks
where Span gas of several different concentrations is needed.
•
In either case, we recommend using a Gas Dilution Calibrator such as a TAPI Model T700
with internal photometer option.
In the case of O
3
measurements made with the Model T400 photometric ozone analyzer,
it is recommended that you use a span gas with an O
3
concentration equal to 90% of the
reporting range for your application.
EXAMPLE:
•
If the application is to measure between 0 ppm and 500 ppb, an appropriate span gas
would be 450 ppb.
•
If the application is to measure between 0 ppb and 1000 ppb, an appropriate span gas
would be 800 ppb.
2.3.2.1 PNEUMATIC CONNECTIONS: BASIC CONFIGURATION
VENT
here if input
is pressurized
Source of
SAMPLE GAS
Removed during
calibration
MODEL 701
Zero Gas
Generator
Gas Dilution
Calibrator
Instrument Chassis
ZERO AIR
DRY AIR
SAMPLE
EXHAUST
SPAN
Enclosure Wall
VENT
here if output of
calibrator is not already vented
Figure 2-13. Gas Line Connections for the T400 Analyzer – Basic Configuration