Peformance Checks and Troubleshooting

The Dasibi 1008 Series Ozone Monitor

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.

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.

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.

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’.

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.

Zero Check

Set the mode switch to ZERO.The front panel display should read 00.000Take 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.

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.

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.

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.

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.

Temp. Check (cont)

A value will appear in Celsius.The display should read about 30 C.

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.

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).

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.