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OPERATING INSTRUCTIONS M400E Ozone Analyzer Operator’s Manual
In general, ambient monitors are always calibrated in situ without disturbing their normal sampling setup, except
for transferring the sample inlet from the ambient sampling point to the calibration system.
Calibration should be performed with a primary UV photometer or by a transfer standard (see Section 10.1.4).
The user
should be sure that all flow meters are calibrated under the conditions of use against a reliable
standard such as a soap bubble meter or wet test meter. All volumetric flow rates should be corrected to 25°C
and 760 mm Hg. A discussion of the calibration of flow meters is in Appendix 12 of Ref. 11.
A newly installed M400E should be operated for several hours or preferably overnight before calibration to allow
it to stabilize. A brand new M400E (fresh from the factory) may require several days of operation to fully
stabilize. Allow the photometer or transfer standard to warm up and stabilize before use, particularly if stored or
transported in cold weather.
10.3.2. MULTIPOINT CALIBRATION PROCEDURE
Multipoint Calibration consist of performing a calibration of the instrument’s Zero Point and High Span Point,
then checking its accuracy at various intermediate points between these two.
The procedure for performing the Zero Point and High Span Point are identical to those described in Section
9.2.3.
After the Zero
and High Span points have been set, determine five approximately evenly spaced calibration
points between the Zero and High Span Point.
For each midpoint:
ZERO CAL M RANGE = 500.0 PPB O3 =XXX.X
< TST TST > ZERO SPAN CONC EXIT
WAIT 10
MINUTES
Or until the
reading
stabilizes and
the SPAN button
is displayed
SAMPLE RANGE = 500.0 PPB O3 =XXX.X
< TST TST > CAL
CALZ
CALS
SETUP
Record the O
3
reading as
displayed on the
instrument’s front
panel
Press EXIT to
Return to the
Main SAMPLE
Display
A
CTION:
Allow Calibration Gas diluted to
proper concentration for Midpoint N
ACTION:
Allow Calibration Gas diluted to
proper concentration for
Midpoint N+1
Plot the analyzer responses versus the corresponding calculated concentrations to obtain the calibration
relationships. Determine the straight line of best fit (y = mx + b); determined by the method of least squares
(e.g., see Appendix J of Volume I of the Q.A. Handbook
6
).
After the best-fit line has been drawn, determine whether the analyzer response is linear. To be considered
linear, no calibration point should differ from the best-fit line by more than 2% of full scale.
176 04315 Rev. C1