Ludlum Measurements 3100, Руководство пользователя

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A-4
f. Once the gauge is showing -10 inHg vacuum, click on the Pressure Calibration button. A dialogue box
will appear to enter Low Pressure Value in kPa. This value is calculated by subtracting 33.86 from the
current atmospheric pressure obtained in the first step of this section.
g. Once the Low Pressure Value has been entered, select the Take Voltage Readings button.
h. The Voltage readings will populate in the window (ensure that these values are fluctuating near the
displayed average voltage reading.) Once the status bar has completed, press the ACCEPT button in
lower right corner of the dialogue box. Two possible problems indicated by non-fluctuating values
could be a loss of communication between the software and instrument or a loss of vacuum.
i.
The next dialogue box will appear to enter High Pressure Value. Remove the vacuum pump from the
pressure sensor before proceeding. Then select the Take Voltage Readings button.
j.
The voltage readings will populate in the window (ensure that these values are moving around the
average.) Once the status bar has completed, press the ACCEPT button in the lower right corner of the
dialogue box.
k.
The next dialogue box will appear as a reminder to update the new calculated pressure values. Press
OK.
l.
The UPDATE button on the main window must be selected to save the new Pressure Calibration Slope
and Offset.
A.1.5 Airflow Calibration.
This step in calibration is optional and is recommended for new instruments or
whenever airflow miscalibration is suspected.
a. Connect a calibrated airflow meter to the input (the port labeled IN) of the Model 3100.
b. Operate the instrument in SAMPLE mode, and compare readings from the external flowmeter to the
Model 3100 displayed value.
c.
If there is a significant difference between the two readings, adjust the Airflow Cal Constant value on
the Pressure/AirFlow tab of the software until the two readings match.
Note: Since this instrument utilizes a diaphragm pump, airflow readings taken from the outlet (port labeled OUT) of
the Model 3100 may be incorrect.
A.1.6 Zeroing: Electrometer Offset.
a. Adjust the Electrometer Offset value in software in order to change the background display value to 0
µCi/m
3
. This value shall be between 2.000 and 2.100
b.
If using the Electrometer Calibration Wizard, target a filtered ADC average as close as possible to zero
without being a positive value.
Note: It is recommended to confirm that the instrument is zeroed correctly by enabling streaming. Streaming
through the software is recommended since the data shown has better resolution. The instrument readings should be
less than 1.000 µCi/m
3
, but occasionally greater than 0.000 µCi/m
3
.
A.1.7 Tritium Calibration.
The Model 3100 calibration software is used to adjust the calibration constants for each
of the three tritium ranges – from 1to 100 µCi/m
3
, from 100 to 1000 µCi/m
3
, and from 1000 to 10,000 µCi/m
3
.
These three Calibration Constants are found on the
3
H Calibration tab of the software.
a. There are four calibration methods for calibration of the tritium readout on the Model 3100.