Teledyne 9110EH - Nitrogen Oxides Analyzer - Manual (Page 149)

Model 9110EH Instruction Manual EPA Protocol Calibration
assumed that only the volume of the reaction cell, V
RC
, and the concentration of the NO
standard, [NO]
STD
, are known. All flow settings (F
NO
, F
O
, F
T
, and F
D
) will be calculated. In
many uses, these flow settings are known and need only to be substituted in Equations 8-5
and 8-6 to verify the required conditions. Before doing any calculations, the URL and flow
demand of the analyzer being calibrated must be known. Operating parameters are
determined from the operations manual:
• Upper range limit = 0.5 ppm, and
• Flow demand = 500 cm
3 /min.
• Volume of calibrator reaction cell is determined by physical measurement: V
RC
= 180
cm 3
• The concentration of the NO standard gas to be used is determined by reference
against an NIST-SRM (Section 2.0.7, Q.A. Handbook): [NO]
STD
= 50.5 ppm
Determine the minimum total flow (F
T
) required at the output manifold using Equation 8-1:
F
T
= 500 cm 3 /min (110/100) = 550 cm 3 /min
Because low flows are difficult to control and measure, it is often advantageous to set a
higher total flow than needed. In this example, we will set F
T
to 2750 cm 3 /min.
Determine the highest NO concentration, [NO]
OUT
, required at the output manifold, using
Equation 8-2:
[NO]
OUT
= 0.5 ppm (90/100) = 0.45 ppm
Calculate the NO flow (F
NO
) required to generate the NO concentration [NO]
OUT
, using
Equation 8-3:
min / cm 24.5
ppm 5 . 50
min / cm 2750 ppm 45 . 0
= F 3
3
NO
=
×
Calculate the required flow rate through ozone generator (F
O
) using Equation 8-4:
min cm 24.5 -
min - ppm 2.75
cm 180 x /min cm 24.5 x ppm 50.5
= F 3
3 3
O
/
/min cm 260 = /min cm 24.5 - min / cm 80984 = 3 3 2 6
Verify that the residence time (t
R
) in the reaction cell is <2 min using Equation 8-5:
min 63 . 0
min / cm 5 . 24 min / cm 260
cm 180
= t
3 3
3
R
=
+
Verify the dynamic parameter specification (P
R
) of the calibrator reaction cell using
Equation 8-6:
min ppm 75 . 2
min / cm 5 . 24 min / cm 260
cm 180
min / cm 5 . 24 min / cm 260
min / cm 24
ppm 5 . 50 =
3 3
3
3 3
3
R
− =
+
Ч
+
Ч P
M9110EH Rev 0 135