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6.5.3 Continuous measurement
For the continuous measurement, expert knowledge from the helium leak test
department is required.
During the continuous measurement, the device provides continuous measurement
results, but as sensor current in amperes rather than as a leak rate. It is therefore not
possible to set a trigger value. The sensor current changes by approx. 1,5 × 10
-7
amperes per mbar of helium at the sensor. It is your task to interpret the current
signal.
Whether a GROSS or a FINE measurement takes place is also set manually: In the
measurement window, select “Select GROSS” or “Select FINE”.
Fig. 22: Display of the reference values during a continuous measurement
The measurement begins when you select “Start”. Selecting “Stop” switches from the
measurement line to the reference line.
If you interrupt the measurement, you should always switch to the reference line using
“Stop” or select standby, see Standby [
}
56]. This preserves the sensor.
6.6 Settings for the measurements
When you have decided on an operating mode, set the parameters for the
measurement.
Trigger level 1 and 2 Accumulation measurement: If a trigger value greater than 1 × 10
-3
mbar l/s per liter of
the net volume is set, the device automatically carries out a turbo
measurementOperation modes [ } 47].
Carrier gas measurement: The set value determines the measurement time and
decides whether a FINE measurement takes place after the GROSS measurement,
see Operation modes [
}
47]. The limit is 6.7 × 10
-7
mbar l/s per sccm of the carrier gas
flow.
The limit is automatically increased by the device if you are working with diluted
helium and have made the corresponding change to the device settings.
A second trigger level can be helpful for the assessment of the measurement values.
You can activate the trigger level under “Trigger lever 2” and set a value. If you set a
very high value here, the display range is also expanded upwards.