Agilent Technologies Helium User Manual page 105

Technical Information
Mass Flow Meter Setup Configuration
The following figure depicts the connection required to use the Alicat mass flow
meter in a test setting. This setup connects from the leak detector test port to the
fine metering valve assembly, to the mass flow meter (fitted on both ends with
1/4" NPT NW25 fitting (Agilent part number KAMP250250S), to the hose. This
series is important to be fitted in this order to ensure optimal helium response time.
Instead of this setup using the purchased metering valve, the operator may choose
to use the setup outlined, though that configuration can be awkward to hold as a
probe. The mass flow meter must be kept above a metering valve, whether the
sniffer probe, or the fine metering valve described. This keeps the mass flow meter
close to atmospheric pressure, ensuring maximum accuracy.
Figure 51 Alicat Scientific Mass Flow Meter Supported Method of PPM Testing
The hose may be connected to the inlet side of the mass flow meter. One
connection technique is described here, if you desire to purchase the Agilent sniffer
power probe. 1/16" ID hose may be used alone, by itself as a sniffing probe, though
it will not have a handle.
Figure 52 Alicat Scientific Mass Flow Meter Supported Method of PPM Testing
Agilent Helium Leak Detector User Manual 105