Met One E-BAM, Руководство по эксплуатации

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E-BAM-9805 Manual Rev B.docx Page 41
5.4 Background Determination (Mass Offset)
It is recommended that the E-BAM undergo a background test annually and after any major repairs
have been performed.
Required Tools : Zero Filter (Met One Instruments Part No. BX-302)
Use the following steps to conduct a zero-filter background test and set the mass offset.
1. Ensure that the E-BAM has been calibrated and that leaks are not present.
2. Go to the Operate menu and select Stop Sample to stop the current sample.
Figure 5-5 BX-302 Zero Filter Assembly
3. Remove the size selective inlet(s) from the sample tube and install the zero filter.
4. Verify that the zero-filter leak valve is in the open position.
5. Go to the Setup menu and select Background.
6. Set the Background value to zero (see section 3.6.3 for details).
7. Exit the Background menu, go to the Operate menu, select Start Sample, and begin
sampling.
8. After no less than 48 hours, retrieve the E-BAM hourly concentration data. Confirm that the
monitor ran without disruption. If errors, power outages or maintenance occurred, the test will
have to be restarted.
9. Calculate the average of the most recent 48 hourly PM concentrations. This allows the first
few hours of the test to be used for warming up the system and allowing it to stabilize before
collecting data for the 48 -hour average. Record this value.
10. Calculate the new Background value by determining the negative of the 48-hour average
calculated in Step 9. For example, if the 48 hour mean = 1.07 µg /m3, the new Background
would be -1.07 µg/m3. Since all Background values are entered in units of mg/m
3
, round to
the fourth decimal place and use -0.0011 mg/m
3
.
11. Return to the Setup menu and select Background.
12. Enter the new Background value.