Introduction to HM70 - HM70

HM70 Quick Guide

Document code
M212070EN
Revision
B
Language
English
Product
HM70
Document type
User guide

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 consists of 2 main units: Vaisala Handheld Measurement Indicator MI70 and the HMP75/HMP76/HMP77 probe.

HM70 can be used to measure the following parameters:

Table 1. Display parameters
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

This Quick Guide introduces the features of the MI70 indicator and the basic measurement procedure with the HM70 meter.

The HM70 User Guide (M210297EN) at www.vaisala.com/hm70 contains product specifications and instructions for operating and maintaining HM70, and using it together with the following Vaisala instruments: HMT120, HMT140, HMT330, PTU300, HMT310, and HMP155.

Using HM70 with other Vaisala instruments is discussed in the respective User Guides, also available at www.vaisala.com:
  • HMP60 and HMP110 Series User Guide (M211060EN)
  • HMDW110 Series User Guide (M211726EN)
  • HMW90 Series User Guide (M211399EN)
  • HMD62 and TMD62 User Guide (M212016EN)
  • HMD65 User Guide (M212243EN)
  • GMW90 Series User Guide (M211659EN)
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.