Calibration – Dasibi Ozone
Using the 1008-PC
When to Calibrate
If an ozone monitor is out in the
field, must be done every (3)
months per CFR 50 regulations.
Must be done after replacing the
ozone scrubber assembly, solenoid
valve, pump, or UV lamp.
NOTE: Make sure to complete the Performance checks
Connect the scrubber to a particulate
matter filter and then to inlet.
Connect one ozone output manifold to
inlet of 1008-PC.
Connect second output to another
monitor to be calibrated.
Make sure each connection is firmly
attached to each port for air flow.
Setting Up the Calibration
Calibration Procedure with 1008-
1. After connections are set properly, set the mode to „Operate‟
and turn on the 1008-PC and the other monitor to be calibrated.
Set the switch next to the thumbwheel to „Auto.‟
2. The instrument will be tested at concentrations of 400, 300,
200, 90, 50, and 0 ppb. Start with 400 ppb and decrease.
Make sure to allow each instrument being calibrated to
run for at least an hour so the lamp and other elements
inside reach operational temperatures. The lamp is the
main element that needs to be warm, so the pumps
can be off.
For 0 ppb, make sure to turn the ozone generator
switch to „Off‟ and switch from „Auto‟ to „Manual‟ mode,
or else sporadic ozone readings may result.
3. Note the response time of each instrument; it should
obtain within 90% of the value within 5 to 10 minutes.
Run each concentration for at least 30 minutes. At 0-ppb,
the instrument should within 1 or 2-ppb of the offset value
that is set on the D/A board.
4. Record the number reached after 30 minutes; if not
within at least 90% within 10 minutes, disconnect monitor
and troubleshoot for leaks or other possible problems.
What do the numbers
1008-PC 400 300 (298) 200 90
1008-RS 370 281 186 82
% 92.5 94.2 93.0 91.1
Here is a table showing what happened from an actual test. Note that the percentages are
relatively the same. The 1008-RS ozone monitor passed the system leak test as well as all the
span checks and other checks as shown in the manual. The 1008-PC is the reference monitor.
Conclusion: Probably needs a new solenoid valve even though it passes the system leak test.
However, don’t hesitate to recheck all connections and settings on the respective instruments and
retest just to be sure.
Rule of Thumb
If low readings recorded, but linear
or same percentage difference, it is
likely to be a solenoid problem.
If non-linear results recorded at high
or low end, then the scrubber is
The scrubber should have Activated Charcoal, Type F-300,
The practical lower limit of ozone generation for the 1008-
PC is a thumbwheel setting of 50-ppb.
Another test against a 1008-PC and another monitor is to
set the thumbwheel to a setting of at least a 100-ppb or
more. Set the switch to „Manual‟ and leave the setting at
„Operate.‟ See if the ozone monitors read about the same.
The 1008-PC may not necessarily generate 100-ppb in
manual mode, but the point of the test is to see how close
the instruments read.
Make Sure To:
Ideally, you should run the ozone calibration
procedure under a lab fume hood.
Make sure to allow each instrument that is
checked to warm up for at least an hour.
Complete performance checks (system leak test,
lamp frequency, control frequency, etc.) before
With a new scrubber:
It is necessary to „condition‟ the
scrubber by having a high amount of
ozone (400 ppb) exposed to it for at
least an hour. This will help the
ozone monitor have a better
response time and a more accurate
reading. Only for a new scrubber.
A Discussion of the “offset”
It is recommended to operate the
ozone monitors with an offset of „9‟.
The offset is tested by turning on
the monitor and setting the mode
switch to „Span‟. Compare the
number to the thumbwheel settings
on the „D/A Board‟.
Offset discussion continued:
Make note of the offset before
calibrating in each monitor.
If each monitor has an offset of „9‟,
then you can subtract 9 from each
reading for comparison or compare
as is. The percent difference will still
be the same.