Humidity - GE Optica Operator's Manual

Appendix B. Humidity Equations and Conversion Chart
B.3 Humidity
Relative Humidity is defined as the ratio of the water vapor pressure (e) to the saturation vapor pressure (e
prevailing ambient or dry bulb temperature (Ta):
Absolute humidity is expressed as water vapor density: water vapor mass per unit volume of dry air, according to the
following:
Water vapor content expressed as parts per million by volume is given by the following:
Expressing water vapor content as parts per million by weight (or mixing ratio) requires multiplication of the above by
the ratio of the molecular weight of water to that of air as given by the following:
See Figure 50 on page 93 for a graphical humidity conversion chart.
92
E
 
---- -
= 100 = 100
%RH
 
E
S
(
216.7E T
G
D
------ - = ------------------------- -
3 T 273.16 +
M
(
E T
6
PPM = 10 --------------------- -
V
P E T
–
×
PPM = 0.622 10
W
( )
E T
W D
------------------- -
( )
E T
WS A
)
)
D
( )
D
6 E
---------- -
P E
–
) at the
S
Optica™ Operator's Manual