Vaisala HM70 - Manual (Page 11)

Chapter 2 ________________________________________________________ Product Description
VAISALA ________________________________________________________________________ 9
CHAPTER 2
PRODUCT DESCRIPTION
Vaisala HUMICAP
®
Hand-Held Temperature and
Humidity Meter HM70
HM70 consists of two main units: MI70 indicator and
HMP75/HMP76/HMP77 probe. HM70 Hand-held humidity meter
incorporates Vaisala's advanced HUMICAP
®
technology which
enables reliable and high performance humidity measurement.
HM70 is available with an optional, ready-to-use Microsoft
Windows
®
software, which allows an easy way to handle
measurement data using a serial line or a USB instrument cable.
Vaisala HM70 is delivered with a factory calibration certificate.
Display Parameters
- RH relative humidity (% RH)
- T temperature (
°
C/
°
F)
- T
d/f
: dewpoint/frostpoint
1)
temperature (
°
C/
°
F)
- T
d
: dewpoint temperature
2)
(
°
C/
°
F)
- a : absolute humidity (g/m
3
/ gr/ft
3
)
- x : mixing ratio (g/kg / gr/lb)
- T
w
: wetbulb temperature (
°
C/
°
F)
- H
2
O: humid air volume/ dry air volume (ppm)
- pw: water vapour pressure (hPa/ lb/in
2
)
- pws: saturation water vapour pressure(hPa/ lb/in
2
)
- h : enthalpy (kJ/kg / Btu/lb)
- a
w
: water activity
1)
T
d/f
shows dewpoint temperature above the freezing point
(0
°
°C/32
°
°F) and frostpoint temperature T
f
(dewpoint over ice)
below the freezing point.