Linearity Check - Thermo Scientific 49i Instruction Manual

Linearity Check

Thermo Fisher Scientific
7. Replace access fittings used in steps 4 and 6 above and make sure they
are leak tight.
8. Connect the calibrated ozone analyzer to the access port on the outlet of
absorption cell of Cell A.
9. From the Service Mode menu, select Intensity Check. From the
Intensity Check menu, select Int B Reference Gas. Wait for a steady
reading and record the intensity as R(a)
10. Connect the calibrated ozone analyzer to the access port on the outlet of
absorption cell of Cell B. From the Service Mode menu, select Intensity
Check. From the Intensity Check menu, select Int A Reference Gas.
Wait for a steady reading and record the intensity as R(b)
11. Replace access fittings used in steps 8 and 10, and make sure they are
leak tight.
12. Compute percent of ozone loss from the following equation:
Percent of Ozone Loss =
R 1/4[R(a)
m input
If the ozone loss is greater than 2%, check that the absorption cells and
Teflon® tubing have not become contaminated by dirt. See "Optical Bench
Cleaning" in the "Preventive Maintenance" chapter for more information.
If the cells and Teflon® tubing are clean, recondition the optical bench by
setting the ozone generator for maximum ozone and adjust the pressure
regulator for minimum dump flow (about 1/2 liter per minute). Let the
calibration photometer run overnight sampling the high level of ozone.
Then repeat ozone loss test.
Since the Model 49i is inherently linear over the range of interest
(0-1 ppm), a linearity test is an effective overall test that the instrument is
operating properly. The checks above should identify whether any causes of
non-linearity are present. The possible causes of non-linearity are:
Calibration Photometer System Preparation
.
out
R(a) R(b) R(b)
out input
R
m
Calibration
.
out
]
(1)
out
100 %
Model 49i Instruction Manual 4-5