Some slides for troubleshooting the Dasibi 1008 model ozone monitor.

1. Peformance Checks and
Troubleshooting
The Dasibi 1008 Series Ozone
Monitor

2. Sample Flow Check
Make sure the pump is on and then tap the
analyzer flowmeter to make sure the float is
not stuck.
The flowmeter should read about 2 l/min.
Even though the instrument flow independent,
flow should not be <1.5 l/min or >3.5 l/min.
The flow rate can be further validated using a
flow meter that corrects for temperature and
pressure.

3. Span Check
Turn the mode switch to SPAN.
Record the displayed value.
The digits must read 30.8 and the last
two numbers dependent on what zero
offset has been set in the instrument.

4. Recorder Span Check
Turn the mode switch to SPAN.
Take a voltmeter, set it to VDC (select
minimum value), and touch the Red lead to
(+) and the Black lead to (-) at the rear of the
sintrument.
The voltmeter should read 0.800V or 80% of
full scale. If not adjust to proper value by
turning the “Analog Span” at the front of the
instrument.
Check recorder output to see if it matches
display.

5. Recorder Span Check (cont.)
Sometimes at the higher end, the output
voltage may not match the display (0.400 on
display, but 0.396V at recorder terminal). Use
the following procedure to adjust output
voltage variation:
1.Move operator switch to “Span”. Should see
30809 if “zero” offset thumbwheel at ‘9’.
2.Adjust output voltage to 0.800V as in previous
slide if necessary.
3.Open the unit, and adjust the “zero” offset to
‘0’. Set the LSD thumbwheel to ‘400’.

6. 4. Check voltage output to see how close it is
to 0.400V. Adjust analog span pot on front
panel of monitor accordingly.
5. Adjust LSD thumbwheel to some other
values like 2 or 3. It is better to adjust span
pot on the upper end of the scale, and then
the lower ends should be better.
6. Return “zero” offset to chosen preset value.

7. Zero Check
Set the mode switch to ZERO.
The front panel display should read 00.000
Take a voltmeter, set it to VDC (0 to 2V
minimum), and touch the Red lead to (+) and
the Black lead to (-).
The voltmeter should show 0V.
If not adjust, span pot on the right hand side
of “D/A” Board.

8. Control Frequency Check
Set the mode switch to CONT/PRESS.
Set the T/P switch to OFF.
Record the value. It should be 500kHz,
or very close to 50.000 on the display.

9. Sample Frequency Check
Mode switch set to SAMP/TEMP.
T/P switch set to OFF.
VALVE switch set to OFF.
Record the value. If below 35, try to
adjust the UV lamp position.

10. Adjusting Lamp Frequency
Loosen the two screws at right hand corner of
instrument. Gently push the lamp forward to
increase frequency; pull out to decrease lamp
frequency.
Note: Use a plastic pen or some other
insulated tube to push or tug the lamp in or
out of the UV lamp housing. Do not pull the
lamp out while instrument is on since UV is
harmful to the eyes.

11. Temperature Check
Disconnect all gas lines from back
panel. Ozone monitor must be warmed
up (about an hour).
Set mode switch to SAMP/TEMP.
T/P switch set to ON.
Analyzer PUMP switch set to OFF.
VALVE switch set to OFF.

12. Temp. Check (cont)
A value will appear in Celsius.
The display should read about 30 C.

13. Pressure Check
Disconnect all lines from back panel.
Mode switch set to CONT/PRESS.
T/P switch set to ON.
Analyzer PUMP switch set to OFF.
Compare displayed value with a
barometer. The value on the ozone
monitor is in Pascals.

14. System Leak Check
Mode switch set to CONT/PRESS.
T/P switch set to ON.
Analyzer PUMP switch set to ON.
VALVE switch set to ON.
Analyzer flow within an acceptable
range (1.5 l/min to 3.5 l/min).

15. System Leak Check (cont)
Plug the INLET. The flow should drop to zero
within about a minute.
If it does not reach zero, there is a leak in the
system.
Check internal plumbing connections to
scrubber, valve, or other points. Check optics
tubes to see that each is screwed firmly and
that seals in place if removed for cleaning.