Vaisala HUMICAP® Handheld Humidity and Temperature Meter HM70 measures relative humidity and temperature accurately in measurement range −70 … +180 °C (−94 … +356 °F), depending on the probe model. HM70 incorporates the advanced Vaisala HUMICAP® technology that enables reliable and high-performance humidity measurement. HM70 consists of 2 main units: Vaisala Handheld Measurement Indicator MI70 and the HMP75/HMP76/HMP77 probe.
| Parameter | Abbreviation | Metric unit | Non-metric unit |
|---|---|---|---|
| Relative humidity | RH | %RH | %RH |
| Temperature | T | °C | °F |
| Dew point/frost point temperature 1 | Td/f | °C | °F |
| Dew point temperature 2 | Td | °C | °F |
| Absolute humidity | a | g/m3 | gr/ft3 |
| Mixing ratio | x | g/kg | gr/lb |
| Wet bulb temperature | Tw | °C | °F |
| Humid air volume/dry air volume | H2O | ppm | ppm |
| Water vapor pressure | pw | hPa | lb/in2 |
| Saturation water vapor pressure | pws | hPa | lb/in2 |
| Enthalpy | h | kJ/kg | Btu/lb |
| Water activity | aw | aw | aw |
1 Td/f shows dew point temperature above the freezing point (0 °C/32 °F) and frost point
temperature Tf (dew point over ice) below the freezing point.
2 Td shows dew point over water throughout the entire measurement range.