Vaisala DRYCAP DMT345 Uživatelská příručka stáhnout pdf (Strana 153)

Appendix B ______________________________________________________ Calculation Formulas

VAISALA ______________________________________________________________________ 153

APPENDIX B

CALCULATION FORMULAS

This Appendix contains the formulas used for the calculated output

quantities.

The DMT346 series transmitters measure relative humidity and

temperature. From these values dewpoint, mixing ratio, absolute

humidity and enthalpy in normal pressure are calculated using the

following equations:

Dewpoint:

log

















(1)

is the water vapor pressure.The parameters A, m, and T

depend on

temperature according to the following table:

t A m T

<0 °C

6.1134 9.7911 273.47

0 ... 50 °C 6.1078 7.5000 237.3

50 ... 100 °C 5.9987 7.3313 229.1

100 ... 150 °C 5.8493 7.2756 225.0

150 ... 180 °C 6.2301 7.3033 230.0

1) Used for frostpoint calculation if the dewpoint is negative

Mixing ratio:

99.621 

(2)

1 2 ... 148 149 150 151 152 153 154 155 156 157

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Vaisala DRYCAP DMT345 Uživatelská příručka Strana 153