Agilent Technologies Helium Leak Detector
98
DRAFT 12
/11/17
Connecting from 3/16" tubing to 1/16" tubing may be accomplished using McMaster-Carr
part number 2808K105. 1/16" tubing should be used as the long line sniffer in this
application, not the thicker 3/16" ID tubing. The thinner tubing gives a faster response time
for a helium signal. 3/16" ID tubing may be purchased as McMaster-Carr part number
6516T53. This tubing should only be used as an adapter section or as use if not using a mass
flow meter. The mass flow meter restricts flow speed, requiring a thinner tube to be used for
a quick response time. 1/16" ID tube may be purchased as McMaster-Carr part number
6516T62.
Since a thin hose is required without a fine metering valve on the top of the system, if the
operator already has a power probe handle that is not in use, the gun portion of the probe
may be disassembled, striped of all valves and copper tubing, and reassembled with a 1/16"
hose inside. It is important, however, not to have another metering valve in series above the
mass flow meter. This is for optimizing response time. Of course, this only provides a
convenient handle. A naked hose may be used for sniffing.
Figure 5-21 Re-purposing a Power Probe for Thin Hose Without a Regulator
5.1.3.10.6 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).
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