Eco Physics CLD 780 TR - Page 157

E C O P H Y S I C S Gas Phase Titration
CLD 780 TR / July 2000 154
A3.4 Dynamic parameter specification
a) Adjustment of O
3
Generator and NO Flow Rates
The O
3
generator air flow rate (F
O
) and NO flow rate (F
NO
) (see Fig.
A.3) must be adjusted such that the following relationship holds:
P
R
= [NO]
RC
x t
R
≥
2.75 ppm-min [2]
[NO]
RC
= [NO]
STD
x (F
NO
/( F
O
+ F
NO
)) [3]
t
R
=V
RC
/( F
O
+ F
NO
) <2 min [4]
where:
P
R
= Dynamic parameter specification, determined empirically,
to insure complete reaction of the available O
3
, ppm-min.
[NO]
RC
= NO concentration in the reaction chamber, ppm.
t
R
= Residence time of the reactant gases in the reaction cham-
ber, min.
[NO]
STD
= Concentration of the undiluted NO standard, ppm.
F
NO
= NO flow rate, scm
3
/min
F
O
=O
3
generator air flow rate, scm
3
/min
V
RC
= Volume of the reaction chamber, scm
3
b) GPT System flow conditions:
The flow conditions to be used in the GPT system are determined by
the following procedure:
1. Determine F
T
, the total flow required at the output manifold (F
T
=
analyzer demand plus 10 to 50 percent excess).
2. Establish [NO]
OUT
as the highest NO concentration (ppm) that will
be required at the output manifold. [NO]
OUT
should be approxi-
mately equivalent to 90 percent of the upper range limit (URL) of
the NO
2
concentration range to be covered.