GE Moisture Image 1 Series Service Manual page 87

Application of the Hygrometer (900-901D1)
B: Special Case
As mentioned earlier, saturated straight-chain hydrocarbons represent
a special case, where the Henry's Law constant does not vary
appreciably with temperature. In such cases, use the nomograph for
liquids in Figure A-2 on page A-32 to complete the analysis.
Determination of moisture content if the Henry's Law constant (K) is
known.
1. Using a straightedge, connect the known K value on the center
scale with the dew/frost point, as measured with the GE
Panametrics hygrometer.
2. Read moisture content (PPM
scale on the left.
Typical Problems
1. Find the moisture content in benzene, at an ambient temperature
of 30°C, if a dew point of 0°C is measured with the GE
Panametrics hygrometer.
a. From the literature, it is found that C
temperature of 30°C is 870 PPM
b. Using a straightedge on Figure A-2 on page A-32, connect the
870 PPM saturation concentration with the 30°C ambient
W
temperature and read the Henry's Law Constant of 27.4 on the
center scale.
c. Using the straightedge, connect the above K value of 27.4 with
the measured dew point of 0°C, and read the correct moisture
content of 125 PPM
moisture content scale.
2. Find the moisture content in heptane, at an ambient temperature of
50°C, if a dew point of 3°C is measured with the GE Panametrics
hygrometer.
a. From the literature, it is found that C
temperature of 50°C is 480 PPM
b. Using a straightedge on Figure A-2 on page A-32, connect the
480 PPM saturation concentration with the 50°C ambient
W
temperature and read the Henry's Law Constant of 5.2 on the
center scale.
c. Using the straightedge, connect the above K value of 5.2 with
the measured dew point of 3°C, and read the correct moisture
content of 29 PPM
moisture content scale.
) where the straightedge crosses the
W
for benzene at a
S
.
W
where the straightedge crosses the
W
for heptane at a
S
.
W
where the straightedge crosses the
W
June 2003
A-25