Agilent Technologies Helium User Manual page 107

Technical Information
Measuring PPM of Helium with a non-Alicat Scientific brand Mass Flow Meter
Scientific confidence added through accurate computation of both helium leak

rate, and gas flow rate.
Does not require use of known PPM gas mixture (though use is suggested to

check calibration).
Risk of choosing a mass flow meter that is not in the proper range. The mass

flow meter selected should be in the range of SUGGESTED 0 to 1 SLM
(equivalently, 0 to 1000 SCCM).
The smallest mass flow meter that may be used while still functioning. It could be
NOTE
as small as 300 SCCM, though this flow rate may not be capable of reading mass
flow when measuring flows of mobile unit leak detectors (units with larger roughing
pumps).
Alternatively, if using a mass flow meter that is not supported by the leak detector
software (anything other than Alicat Scientific brand mass flow meter):
1 Attach the mass flow meter in series above the Agilent power probe sniffing
gun (Agilent part number K9565306).
2 Attach the mass flow meter to the sniffing gun through use of a KF to
compression port adapter, 1/8" to NW25 (Agilent part number KCP250125),
if using the power probe as the metering valve (see the following figure).
3 Perform an internal calibration.
4 Perform an external calibration using the sniffing probe by:
a. Selecting Calibration > Calibrate With > External Leak.
b. Entering the value of the external calibrated leak. Keep the probe at the inlet
c. Pressing Calibrate.
Figure 54 External Sniff Calibration Setup
Agilent Helium Leak Detector User Manual
of the standard leak.
107