Edgetech PPM1, Operator'S Manual, Page: 7 / 29

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quantity of current used by
the cell is proportional to
the number of water
molecules being
electrolyzed. If the dc
excitation current is
measured, water vapor
content of the gas can be
displayed. This
measurement process
provides a fundamental
measurement of water
vapor. While in a typical
electrolytic cell the rate of
gas flow must be carefully
Figure 3-1 The Phosphorous Pentoxide
controlled by the user for (P
2
O
5
) Moisture Sensor
accurate measurements,
this cell is independent of
gas flow rate. Although a fundamental measurement technique normally does
not require calibration, each cell is calibrated at the Factory before shipment to
the user to compensate for variations in the diffusion membranes. Figure 3-1
shows the moisture sensor.
Figure 3-2 The PPM1 with Wall Mount housing and Moisture Sensor