Vaisala DM500 - Manual (Page 15)

Chapter 2 __________________________________________________________ Product Overview
VAISALA _______________________________________________________________________ 13
CHAPTER 2
PRODUCT OVERVIEW
This chapter introduces the features and advantages of Precision SAW
Hygrometer DM500.
Product Description
DM500 is a high accuracy dewpoint temperature measuring
instrument capable of measuring dewpoints down to -75 ºC with an
accuracy of ± 0.2 ºC.
The DM500 system consists of the user interface unit DMI500 and the
dewpoint sensing unit DMP501. Four of the following quantities can
be displayed at a time:
- Dewpoint/frostpoint T
d/f
(ºC or ºF), more about dewpoint/frostpoint
on page 128.
- Dewpoint T
d
(ºC or ºF)
- Partial water vapour pressure P
w
(mbar)
- Humid air volume/dry air volume H
2
O (ppmv)
- Relative humidity RH (%)
- Wet-bulb temperature Tw (ºC or ºF)
- Absolute humidity a (g/m3 or gr/ft3)
- Mixing ratio x (g/kg or gr/lb)
- Enthalpy h (kJ/kg or btu/lb)
- Difference of T and T
d/f
T (ºC or ºF)
- Temperature T (ºC or ºF)
- Pressure P (bar, hPa, psi, torr)