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Application of the Hygrometer (900-901D1)
Flow Rate
GE Panametrics hygrometers are unaffected by the fluid flow
rate. The moisture probe is not a mass sensor but responds only to
water vapor pressure. The moisture probe will operate accurately
under both static and dynamic fluid flow conditions. In fact, the
specified maximum fluid linear velocity of 10,000 cm/sec for The
M Series Aluminum Oxide Moisture Sensor indicates a
mechanical stability limitation rather than a sensitivity to the fluid
flow rate.
If the measured dew point of a system changes with the fluid flow
rate, then it can be assumed that off-gassing or a leak in the
sample system is causing the variation. If secondary moisture is
entering the process fluid (either from an ambient air leak or the
release of previously absorbed moisture from the sample system
walls), an increase in the flow rate of the process fluid will dilute
the secondary moisture source. As a result, the vapor pressure
will be lowered and a lower dew point will be measured.
Note:
Refer to the
Specifications
chapter in this manual for the
maximum allowable flow rate for the instrument.