Vaisala HM70 Handheld Humidity & Temperature Meter


  • Designed for spot-checking and field calibration
  • Multilingual user interface
  • Shows measurement trends graphically
  • Proven Vaisala HUMICAP sensor technology
  • 3 probe alternatives, temperature measurement range −70 … +180 °C (−94 … +356 °F)
  • 2 probes: also dew point and CO2 probes can be connected simultaneously
  • Displays various humidity parameters
  • Sensor preheat and chemical purge options for demanding conditions
  • Data can be logged and transferred to a PC via MI70 Link software
  • 6-point traceable calibration (certificate included)

Dpstar is a leader in environmental and industrial measurements. Curiosity and innovation are core values in our company. Our extensive knowledge and expertise are materialized in our selection of innovative products. Accurate measurements are essential for healthy indoor air and improving the energy efficiency of buildings. The unique, cutting-edge Dpstar sensor technologies are manifested throughout our versatile range of products. The transmitters have an exceptionally long lifetime and excellent measurement stability, thus being practically maintenance-free. These are among the many reasons why Dpstar’s products are a sustainable choice.

Vaisala HUMICAP HM70 Handheld is designed for demanding humidity measurement in spot-checking applications. It is also ideal for field checking and calibration of humidity instruments.

The Vaisala HM70 includes an MI70 indicator and an optional probe depending on the application.

  • HMP75 with standard plastic grid
  • HMP75B (chemical purge and sensor preheating)
  • HMP76 with standard sintered bronze filter
  • HMP76B (chemical purge and sensor preheating)
  • HMP77 with standard plastic grid and stainless steel netting
  • HMP77B (chemical purge and sensor preheating)

The optional MI70 Link Windows software in combination with a USB connection cable is used to transfer logged data and real-time measurement data from the HM70 to a PC.


MI70 indicator and HMP75 probe dimensions in mm (inches)

HMP76 and HMP77 probe with cable, dimensions in mm (inches)

HMP77 probe dimensions in mm (inches)


  • HUMICAP Technology
    The Vaisala HM70 features the top-notch HUMICAP sensor, known for its reliability and stability. It handles chemical interference well and maintains accuracy even in tough conditions.
  • Chemical Purge
    The chemical purge feature ensures accurate measurements in environments with high chemical concentrations. The sensor preheat option minimizes measurement delays by keeping the sensor dry when inserted into hot and humid processes.
  • Three Probes To Choose From
    Vaisala offers three types of probes: the general-purpose HMP75, the long stainless steel HMP76 ideal for duct spot-checking, and the small HMP77 at the end of a 5-meter cable, perfect for difficult-to-reach spots and on-site calibration of process transmitters. Additionally, the HM70 supports Vaisala’s dew point, carbon dioxide, and moisture in oil probes, enabling measurements in various multiparameter applications.
  • MI70 Link Windows Software
    The optional Vaisala MI70 Link Windows software and the USB connection cable form a practical tool for transferring logged data from Vaisala HM70 to a PC.


HMP75, HMP76, & HMP77 Measurement Performance
Measurement range 0 … 100 %RH
Accuracy (1) (2) At +15 … +25 °C (+59 … +77 °F) ±1 %RH (0 … 90 %RH)
±1.7 %RH (90 … 100 %RH)
At −20 … +40 °C (−4 … +104 °F) ±(1.0 + 0.008 x reading) %RH
At −40 … +180 °C (−40 … +356 °F) ±(1.5 + 0.015 x reading) %RH
Factory calibration uncertainty
(+20 °C / +68 °F)
±0.6 %RH (0 … 40 %RH)
±1.0 %RH (40 … 97 %RH)
Response time (90%) at +20 °C (+68 °F) in still air: HMP75 (with standard plastic grid) 17 s
HMP76 (with standard sintered bronze filter) 60 s
HMP77 (with standard plastic grid and stainless steel netting) 50 s
Typical long-term stability Better than 1 %RH / year
Temperature HMP75 measurement range −20 … +60 °C (−4 … +140 °F)
HMP76 measurement range −50 … +120 °C (−58 … +248 °F)
HMP76 short time measurement range −50 … +180 °C (−58 … +356 °F)
HMP77 measurement range −70 … +180 °C (−94 … +356 °F)
Accuracy at +20 °C (+68 °F) ±0.2 °C (±0.36 °F), see the graph below
Output parameters Dew point, frost point, absolute humidity, mixing ratio, wet bulb temperature, water content, vapor pressure, saturation vapor pressure, enthalpy, water activity
(1) Including non-linearity, hysteresis, and repeatability.
(2) Defined as ±2 standard deviation limits.
HMP75, HMP76, & HMP77 General Specifications
Humidity sensor HUMICAP 180R
HUMICAP 180RC (chemical purge, sensor preheat)
Temperature sensor Pt100 RTD Class F0.1 IEC 60751
Operating temperature range for electronics −40 … +60 °C (−40 … +140 °F)
Standard sensor protection HMP75 Plastic grid
HMP76 Sintered bronze filter
HMP77 Grid with SS netting
HMP75, HMP76, &HMP77 Mechanical Specifications
IP rating IP65 (NEMA 4)
Housing material ABS/PC blend
Probe material Stainless steel (AIS316L)
Probe cable length (between indicator and probe handle) 1.9 m (6.2 ft)
Probe cable length of HMP77 (from handle to the root of probe) 5.0 m (16 ft)
Probe diameter 12 mm (0.47 in)
Weight HMP75 250 g (8.8 oz)
HMP76 350 g (12 oz)
HMP77 500 g (18 oz)
MI70 Measurement Indicator
Operating temperature −10 … +40 °C (+14 … +104 °F)
Operating humidity 0 … 100 %RH, non-condensing
Storage temperature −40 … +70 °C (-40 … +158 °F)
Max. no of probes 2
PC interface MI70 Link software with USB or serial
port cable
Analog output 0 … 1 VDC
Power supply Rechargeable NiMH battery pack with AC adapter or 4 × AA size alkalines, type IEC LR6
Output resolution 0.6 mV
Accuracy 0.2 % full scale
Temperature dependence 0.002 %/˚C (0.01 %/˚F) full scale
Minimum load resistor 10 kΩ to ground
Housing classification IP54
Housing materials ABS/PC blend
Weight 400 g (14 oz)
EMC compliance EN 61326-1, portable equipment
Menu languages English, Chinese, Spanish, Russian, French, Japanese, German, Swedish, Finnish
Display • LCD with backlight
• Graphic trend display of any parameter
• Character height up to 16 mm (0.63 in)
Alarm Audible alarm function
Data logging capacity 2700 real time data points
Logging interval 1 s to 12 h
Logging duration 1 min … memory full
Resolution 0.01 %RH, 0.01 °C/°F, 0.01 hPa, 0.01 aw, 10 ppm / 0.01 %CO2
MI70 Battery Operation Time
Typical charging time 4 hours
Operation times Continuous use 48 h typical at +20 ˚C (+68 °F)
Data logging use Up to a month
Spare Parts & Accessories
Cables Analog output signal cable 27168ZZ
Connection cable for HMT310 series DRW216050SP
Connection cable for HMP155 221801
Connection cable for TMP115, HMD60 series, HMP60 and HMP110 series, HMW90 series, HMDW110 series, and GMW90 series 219980SP
1-m (3.3-ft) flat extension cable for 219980SP CBL210649SP
Probe extension cable (10 m) 213107SP
Connection cable for HMT330 and HMT120/130 211339
Carrying cases Weatherproof carrying case for MI70 and short probe
Weatherproof carrying case for MI70 and long probe
Soft carrying case for MI70 and short probe
Probe accessories Plastic PC grid filter (HMP75) 6221
Membrane filter (HMP75) 10159HM
Sintered bronze filter (HMP75) DRW212987SP
Plastic PPS grid filter (HMP76/77) DRW010276SP
Sintered stainless steel filter (HMP76/77) HM47280SP
Sintered bronze filter (HMP76 standard) DRW212987SP
PPS grid with SS netting (HMP77 standard) DRW010281SP
Probe holder (only for HMP76) HM36915
Others Measurement indicator MI70
USB PC connection cable (for use with MI70 Link
software) (1)
Rechargeable battery for MI70 26755
(1) Vaisala MI70 Link software for Windows 


Vaisala HM70 Handheld Humidity & Temperature Meter_DpstarGroup