PN 305200901, Rev YT
Overview
The 3050-OLV Moisture Analyzer measures trace concentrations of moisture in
a process gas stream. The 3050-OLV is compatible with He, Ar, Ne, Xe, Kr, O
2
, H
2
,
N
2
, NO, CO, CO
2
, light hydrocarbons, natural gas, refrigerants, air, and specialty
gases. Refer to Figure 1-3 for a Gas List. The analyzer is calibrated to measure
moisture contents from 0.1–2,500 PPMV. Data output can be in units of PPMV,
PPMW, dewpoint Centigrade, dewpoint Fahrenheit, (required process pressure
input) lb/mmscf, and mg/Nm
3
.
The heart of the 3050-OLV is a quartz crystal microbalance (QCM) sensor that is
sensitive to moisture. The QCM moisture sensor is simply a quartz crystal oscil-
lator, in which the quartz crystal has been coated with a proprietary hygro-
scopic coating. This coating selectively, and reversibly, absorbs moisture from a
Sample gas stream. As the crystal is exposed to a gas stream containing water
vapor, the hygroscopic coating absorbs moisture from the gas stream, chang-
ing the mass of the coating. Changes in the mass are detected as changes in
the natural resonance frequency of the oscillator.
In the analyzer’s normal operating mode, the QCM sensor is alternately ex-
posed to the Sample gas and a dry Reference gas. A dry Reference gas is
produced by passing a portion of the Sample gas through a Dryer to remove
any moisture present (i.e., the moisture content of the dry Reference is less
than 0.025 PPMV). The dierence in the resonant frequency of the QCM sensor,
as measured when exposed to each of the two gas streams, is a function of the
moisture content of the Sample gas. Thus, the moisture concentration of the
Sample gas is determined from this frequency dierence. The calibration data,
which relates the moisture concentration of the gas stream to the measured
frequency dierence, are stored in an EEPROM within the QCM sensor module.
Figure 1-1.
3050-OLV Analyzer.
Overview | 1-1
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