Vaisala HMP3 Humidity & Temperature Probe


  • RH accuracy up to 0.8 %RH and temperature accuracy up to 0.1 °C (0.18 °F).
  • Temperature measurement range -40 … +120 °C (-40 … +248 °F).
  • Compatible with Indigo series transmitters.
  • PPS plastic grid filter with stainless steel mesh delivered as standard.
  • Modbus RTU over RS-485 for flexible connectivity.
  • Includes traceable calibration certificate.

Dpstar is a leading supplier of environmental measurement sensors for temperature, relative humidity, pressure, dew point, CO2, and other environmental condition monitoring for industrial process application and research. Since the ’90s, we earned a reputation as a trusted partner to our clients through our commitment and dedication. We are an authorized distributor and supplier of measuring sensors solutions from renowned manufacturers Vaisala. Vaisala is a global leader in environmental and industrial measurement. Building on 80 years of experience, Vaisala provides observations for a better world. Vaisala is a reliable partner for customers around the world, offering a comprehensive range of innovative observation and measurement products and services.

Vaisala HUMICAP Humidity and Temperature Probe HMP3 is a general-purpose probe designed for processes with moderate humidity and temperature levels. The probe structure allows the sensor to be replaced in the field without tools, making it suitable for applications such as industrial HVAC systems, paint booths, clean rooms, environmental chambers, and applications where periodic recalibration is not sufficient for maintenance. HMP3 is part of the Indigo family and is compatible with Indigo500 and Indigo200 series transmitters. It can be used with Vaisala Insight PC software for data visualization, easy probe configuration, and field calibration.


Key Benefits

For general purpose humidity and temperature processes

HMP3 is a general-purpose probe suitable for various industrial applications with moderate humidity and temperature levels. It uses Vaisala’s thin-film capacitive humidity measurement technology, which is now the industry standard in humidity measurement. Vaisala’s HUMICAP technology provides the best stability, a fast response time, and low hysteresis in a wide range of applications.

Exchangeable sensor with several filter options

The design is ideal for a range of operating environments and allows for flexible field maintenance. The filter and sensor element are field-exchangeable for applications which require frequent replacements. Filters suitable for the HMP3 include stainless-steel 12 µ mesh filters (for applications such as air control units), sintered stainless-steel filters (for applications where maximum protection against dust ingress is essential), and PPS plastic grid filters for improved humidity response time.

Use standalone or with an Indigo Transmitter

Its measurement intelligence and digital Modbus RTU over RS-485 connection within the probe mean that HMP3 can be used as a standalone device. It can also be easily integrated into other systems. HMP3 is part of the Vaisala Indigo family, so it can be used with Vaisala Indigo series transmitters. The transmitters offer various additional benefits such as a display for data visualization, easy access to probe configuration, and more extensive options for connectivity, supply voltage, and wiring. Whether using the HMP3 on its own or with an Indigo transmitter, it can be connected to the free Vaisala Insight software for easy field calibration, probe configuration, and device analytics. Whether using HMP3 standalone or with an Indigo transmitter, it can be connected to the free Vaisala Insight software for easy field calibration, probe configuration and device analytics.



Measurement Performance
Relative Humidity
Measurement range 0 … 100 %RH
Accuracy at +23 °C (+73.4 °F) 1) ±0.8 %RH (0 … 90 %RH)
Factory calibration uncertainty 2)  ±0.5 %RH (0 … 40 %RH)
±0.8 %RH (40 … 95 %RH)
T63 response time 15 s
Sensor options HUMICAP R2
HUMICAP 180VC 3) 4)
Sensor Pt100 RTD Class F0.1 IEC 60751
Measurement range −40 … +120 °C (−40 … +248 °F)
Accuracy 1) ±0.1 °C (±0.18 °F)
Factory calibration uncertainty 2) ±0.1 °C (±0.18 °F) at +23 °C (+73.4 °F)
1) Defined against calibration reference. Including non-linearity, hysteresis, and repeatability.
2) Defined as ±2 standard deviation limits. Small variations possible; see calibration certificate.
3) Chemical purge feature available with this sensor.
4) H2O2 resistant. With HUMICAP 180VC sensor, accuracy is not specified below −20 °C (−4 °F) operating temperature.
Operating environment
Operating temperature of probe head −40 … +120 °C (−40 … +248 °F)
Operating temperature of probe body −40 … +80 °C (−40 … +176 °F)
Storage temperature −40 … +80 °C (−40 … +176 °F)
Operating environment Suitable for outdoor use
Measurement environment For air, nitrogen, hydrogen, argon, helium, and oxygen 1)
IP rating of probe body IP66
1) Consult Vaisala if other chemicals are present. Consider safety regulations with flammable gases.
Inputs and Outputs
Operating voltage 15 … 30 V DC
Current consumption 10 mA typical, 500 mA max
Digital output RS-485, non-isolated
Protocols Modbus RTU
Output Parameters
Absolute humidity (g/m3) Relative humidity (%RH)
Absolute humidity at NTP (g/m3) Relative humidity (dew/frost) (%RH)
Dew point temperature (°C) Temperature (°C)
Dew/frost point temperature (°C) Water concentration (ppmv)
Dew/frost point temperature at 1 atm (°C) Water concentration (wet basis) (vol %)
Dew point temperature at 1 atm (°C) Water mass fraction (ppmw)
Dew point temperature difference (°C) Water vapor pressure (hPa)
Enthalpy (kJ/kg) Water vapor saturation pressure (hPa)
Mixing ratio (g/kg) Wet-bulb temperature (°C)
EU directives EMC Directive (2014/30/EU)
RoHS Directive (2011/65/EU)
EMC compatibility EN 61326 1, industrial environment
Type approvals DNV GL certificate no. TAA00002YT
Compliance marks CE, China RoHS, RCM, WEEE
Mechanical Specifications
Connector M12 5-pin A-coded male
Weight 302 g (10.65 oz)
Probe AISI 316L
Probe body AISI 316L
Cable jacket FEP
Duct installation kit 210697
Solar radiation shield DTR502B DTR502B
Indigo USB adapter 1) USB2
1) Vaisala Insight software for Windows available at


Vaisala HMP3 Series Humidity & Temperature Probe_DpstarGroup