Vaisala HUMICAP HMT330 SERIES - MODBUS Diagnostic Functions

Appendix B ______________________________________________________ Calculation Formulas
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Parts per million by volume is calculated using:

w
w
v
Pp
P
ppm


6
10
(8)
Symbols:
T
d
= dewpoint temperature (°C)
P
w
= water vapor pressure (hPa)
P
ws
= water vapor saturation pressure (Pa)
RH
= relative humidity (%)
x
= mixing ratio (g/kg)
p
= atmospheric pressure (hPa)
A
= absolute humidity (g/m3)
T
= temperature (K)
h
= enthalpy (kJ/kg)