Gas Phase Titration Mixtures For Oand No - Teledyne T750 User Manual

The calibrator's level of control is so precise that bottles of mixed gases can be used as
source gas. Once the exact concentrations of all of the gases in the bottle are programmed
into the calibrator, it will create an exact output concentration of any of the gases in the
bottle.
G P T
9.2.
AS HASE ITRATION
Because ozone is a very reactive and therefore under normal ambient conditions a short-
lived gas, it cannot be reliably bottled, however, an optional O
in the portable calibrator, which allows the instrument to be used to create calibration
mixtures that include O
This ability to generate O
to create calibration mixture containing NO
precisely mixing bottled NO of a known concentration with O
and diluent gas (zero air).
The principle of GPT is based on the rapid gas phase reaction between NO and O
produces quantities of NO
NO
Under controlled circumstances, the NO-O
therefore the concentration of NO
accurately predicted and controlled as long as the following conditions are met:
•
•
•
•
Given the above conditions, the amount of NO
(at a 1:1 ratio) the amount of O
Since:
•
•
•
Once the TOTALFLOW is determined and entered into the T750's memory and target
concentration for the O
adjusts the NO flow rate and diluent (zero air) flow rate to precisely create the appropriate
NO concentration at the output.
2
156
M
IXTURES FOR
.
3
internally also allows the T750 Portable Calibrator to be used
3
as according to the following equation:
2
O NO
+  →
3
resulting from the mixing of NO and O
2
The amount of O used in the mixture is known.
3
The amount of NO used in the mixture is AT LEAST 10% greater than the
amount O in the mixture.
3
The volume of the mixing chamber is known.
The NO and O flow rates (from which the time the two gases are in the
3
mixing chamber) are low enough to give a residence time of the reactants in
the mixing chamber of >2.75 ppm min.
added.
3
The O flow rate of the T750's O
3
0.105 SLPM);
The GPT chamber's volume is known,
The source concentration of NO is a fixed value,
generator are entered into the calibrator's software, the T750
3
O NO
AND
3 2
generator can be included
3
using a gas phase titration process (GPT) by
2
of a known n concentration
3
ν
O h
+ +
( )
light
2 2
reaction is very efficient (<1% residual O
3
being output by the T750 will be equal to
2
generator is a fixed value (typically about
3
that
3
Equation 9-2
),
3
can be
3
083730750B DCN8606