Hach ORBISPHERE3650 Manuel D'utilisation De Base page 9

valve. The sample flow can be regulated by adjusting the knurled stainless steel knob on top of the
flow chamber.
Minimum flow rates, measurement limits and response times for the various available membranes
are given in the accompanying Sensor Manual.
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.
Note: For measurements of gaseous samples in % units, you must open the barometric pressure sensor relief
valve switch on the top of the instrument from time to time, to allow the pressure inside the instrument to equilibrate
to the barometric pressure.
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
levels. If measurements take place in carbonated samples, precondition with carbonated water.
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.
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.
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
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.
, close off the sample. The sensor is now
2
Clock settings on page 18.
Automatic data acquisition - setting sampling
2
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