Agilent Technologies Helium Leak Detector
DRAFT 12/11/17
93
Figure 5-15 Sniffing Setup
4. If the leak detector is vented - Press the Te
st 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 detecto
r 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” on page 94).
❑ 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” on page 94).
❑ 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 (“Measuring PPM of Helium with a
non-Alicat Scientific brand Mass Flow Meter” on page 98).
NOTE Parts per million (PPM) of helium may be measured using a
helium leak detector 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.
The information icon provides the necessary directions for a suc-
cessful external calibration.
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