Leybold vacuum PhoeniXL300, Техническое руководство

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Working Principle
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GA10.218_1.01 - 11/2004
ZERO-button A constant leak rate reading may be suppressed by pressing the ZERO-
button, i.e. a constant helium background within a test sample. This but-
ton is only active in the measurement mode.
In AUTO mode and ZERO activated the indication limit is set to the high-
est sensitivity range, for. ex. <1E-12 mbar l/s>
The exponent on the hand unit is retained in the case of “Zero” when the
leak rate display always remains at the upper decade of the bargraph dis-
play. If the leak rate is indicated in the lower decade, the exponent is
decremented by one in the case of “Zero”. Thus the displayed leak rate
can always be suppressed by at least one decade so as to increase reso-
lution.
Example:
A leak rate of 4.1 x 10
-8
mbar l/s can be displayed in two ways on the
hand unit:
In both cases the exponent 8 and the bargraph display is dark after pres-
sing ZERO.
With the background set to off pressing the zero button saves the cur-
rently measured value as the “zero level”. However, the internal zero level
setting as in use remains unchanged.
After operating the zero button, only that amount of the currently measu-
red value is substracted so that the display limit is just reached. The dis-
played results of a leak rate measurement will be too high by an amunt
which corresponds to the display limit. Thus also increases in the leak rate
will be visible, which are less than the display limit. Here the internal zero
level is not changed.
It is not possible to reduce the detection limit of the instrument by pres-
sing the ZERO-button. The ZERO function is cancelled by pressing the
ZERO-button once more. The Zero function is also cancelled automati-
cally as soon as the STOP/VENT-button is pressed.
The ZERO function has an effect on all output devices such as remote
control, display, chart recorder, triggers and RS232 interface.
Acoustic signal The acoustic signal is used to indicate the leak rate. An acoustic signal is
also genereated in the case of error messages.
The volume of the acoustic signal can be increased by operating the but-
ton to the left of the loudspeaker. With the button to the right of the
loudspeaker the volume of the acoustic signal may be reduced.
To check this, a signal will be output at the selected volume for 2 seconds
after operating the button. At the same time the volume is indicated on the
seven segment display on the hand unit.
4.1.7 Displays on the Hand Unit
Measurement range display
Here the leak rate is indicated by way of a bar. In case of a range over-
a) The exponent indicates -8 and the narrow part of the bargraph dis-
play is fully on the wider section is on up to number 4.
b) The exponent indicates -7 and only the lower narrow section of the
bargraph display is on up to number 0.4.