Intrinsically Safe Humidity and Temperature Transmitter Series HMT370EX

For use up to zone 0 and 20

Please note that the HMT370EX has been released with ATEX, IECEx, CML, NEPSI, KC, FM, CSA and UKEX certificates for intrinsically safe compliance.

The intrinsically safe HMT370EX is the ideal solution for use in hazardous areas up to zone 0 and 20. In addition to measuring relative humidity and temperature, the transmitter outputs also other humidity parameters: dew point temperature, wet-bulb temperature, absolute humidity, mixing ratio, water concentration, water mass fraction, water vapor pressure, and enthalpy. Special models for moisture in oil and jet fuel measurements are available.

Typical applications

Typical applications include fuel storage tanks, manufacturing of chemicals, pharmaceuticals and food, paint booths, and any other industry or process where intrinsically safe humidity or moisture in oil measurement is required. View the current certificates for the HMT370EX:

Replaces the HMT360 transmitter series

This next-generation HMT370EX transmitter replaces the long-running HMT360 transmitter series.

The HMT370EX offers several probe options for different applications:

  • HMP371 - for wall mounting
  • HMP373 - for confined spaces
  • HMP374 - for pressurized spaces
  • HMP375 - for high temperature
  • HMP377 - for high humidity
  • HMP378 - for pressurized pipelines

Models for measuring moisture in oil and jet fuel:

  • HMP378F - for moisture in oil
  • HMP378H - for JET A-1 fuel

The HMT370EX uses the superior Vaisala HUMICAP technology


  • Intrinsically safe (Exi)
  • Interchangeable probes
  • Detachable probe module
  • Graphical LCD display and non-display model
  • Vaisala HUMICAP® sensor
  • Compatible with Vaisala Insight PC software
  • Traceable calibration (certificate included)

Key benefits

Intrinsically safe

The entire HMT370EX transmitter can be installed directly in explosive areas. It can withstand continuous exposure to potentially explosive environments that contain flammable liquids, gases or dust. Operation in any of these environments requires no additional protective enclosures.

Detachable probes

Probes can be easily replaced and removed for calibration outside the hazardous area without removing the entire transmitter. Attaching new probes involves minimal reconfiguration, as up-to-date settings can be restored from the transmitter.

Easy to configure

Output configuration and measurement calibration and adjustment can be carried out directly on the optional local display interface. Alternatively, you can connect the transmitter to Vaisala Insight PC software and configure both the transmitter and the probe together or separately.

Product Resources