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Technical Information
Figure 47 Sniffing Setup
4
If the leak detector is vented - Press the Test button in the bottom right hand
corner. Adjust the metering valve on the Sniffing Probe until a desired value
between 5.0E-1 and 1 Torr is obtained.
In this Setup Screen the leak detector can be configured to measure PPM
concentrations of Helium from the following three methods:
Calibrating to a known Helium PPM concentration ("Calibrating to a Known
Helium PPM Concentration").
Monitoring the actual flow rate in real time from a recommended Mass Flow
Meter manufacturer (Alicat Scientific) via the RS232 port to obtain the
calculated Helium PPM concentration at the adjusted test port pressure
("Measuring PPM of Helium with an Alicat Scientific Brand Mass Flow Meter").
Inputting the flow rate (sccm) from any Mass Flow Meter or Mass Flow
Controller via the displayed flow rate reading/value at the adjusted test
port pressure to obtain the calculated Helium PPM concentration
(see "Measuring PPM of Helium with a non-Alicat Scientific brand Mass
Flow Meter")
Parts per million (PPM) of helium may be measured using a helium leak detector
NOTE
that is either used in conjunction with a mass flow meter, or is calibrated using a
known concentration (PPM) of helium. PPM of helium is described as the flow rate
of helium divided by the flow rate of total gas, multiplied by 100. If there are 5 moles
of helium, and 999,995 moles of other gas, then the concentration is 5 PPM helium.
This is a typical concentration of helium at sea level on earth.
Agilent Helium Leak Detector User Manual
The information icon provides the necessary directions for a
successful external calibration.
101
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