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To switch between gas measurement and temperature measurement, press the Up/Down Arrow
buttons.
To backlight the LCD for approximately three minutes, press the Backlight button.
4.3 Preconditioning sensors
You can expect a more rapid and accurate first result if you precondition the sensor before you take
readings. You may want to precondition prior to each series of measurements, depending on
frequency of use.
To precondition, connect the flow chamber to a convenient sampling source at or below expected O
or H
levels. If measurements take place in carbonated samples, precondition with carbonated water.
2
Open the sampling valve on the flow chamber, just enough for a trickle. Then, switch on the
instrument and watch the LCD. You will see the values drop.
Typically for oxygen, if you are measuring in the 0.1 ppm range, then only a short time is required for
the display to fall to this level, whereas ppb level measurements may require the sensor to remain
exposed to the sample for half an hour or more. You will establish your own requirement with
experience.
Once the LCD displays the expected level of O
preconditioned and ready to use.
4.4 Storing measurements in the instrument
The instrument will store up to 500 gas measurement values, labeled by numbers 0 through 499,
along with the current date and time of each measurement. You have the choice of acquiring this
information manually or automatically, as described below.
Before storing measurements, you should verify the date and time settings of the instrument's
internal clock, as described in
4.4.1 Automatic data acquisition
Note: When the instrument is used to automatically store measurement data, all buttons except the POWER key
are disabled. If enough time elapses to store all 500 values, the instrument will return to normal measurement mode
and the buttons re-enabled.
Before starting automatic measurement storage, first select the sampling rate desired using the
Sampling Rate menu of the WinLog97 program (see
intervals
on page 13).
1. Switch the instrument OFF (by pressing the POWER key).
2. Then hold down the STO button while switching the instrument back ON. The LCD displays the
message Sto for about one second.
3. Normal gas concentration measurements are displayed for about two minutes.
4. After two minutes the instrument displays the sample number (starting at 000), then the gas
concentration measurement value followed by [- - -] to indicate the measurement is being stored.
5. This storage sequence repeats automatically, at the rate specified by the WinLog97 program
Sampling Rate menu. Values are stored sequentially in sample numbers 000 through 499.
Note: If you have not cleared previously stored values, the storage sequence automatically overwrites the older
values, as they are stored.
6. To end automatic storage, switch the instrument OFF (by pressing the POWER key) while it is in
normal measurement mode and not while it is in the process of automatically storing data.
7. Switching ON again without holding down the STO button returns the instrument to measurement
mode.
Note: If you accidentally interrupt the automatic data storage by switching off the instrument while it is in the
process of storing a value, and you then attempt to download the stored values by the WinLog97 program, you
will get a Windows Checksum Error message, and you will not be able to view the measurement data. If this
happens, then go back to the instrument and manually log one more value (as described in
acquisition
on page 10). You can then download your original set of values to your PC.
or H
2
Clock settings
on page 17.
, close off the sample. The sensor is now
2
Automatic data acquisition - setting sampling
2
Manual data
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