HMT331 Humidity and Temperature Transmitter for Wall Mounting, 1%RH accuracy - Vaisala Online Store

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HMT331 Humidity and Temperature Transmitter for Wall Mounting, 1%RH accuracy

The HMT331 is the top-of-the-line wall-mounted transmitter for demanding HVAC and condition monitoring applications. The Vaisala HUMICAP® Humidity and Temperature Transmitter HMT330 series incorporates Vaisala’s 40 years of experience in industrial humidity measurement.

The instrument offers a wide variety of different psychrometric units, including dew point, enthalpy, wet bulb temperature, absolute humidity, and mixing ratio.

The transmitter has a keypad and a large graphical display for convenient monitoring of the reading and transmitter setting changes. For example both output signal type (voltage or current) and scaling can easily be changed by the user.

See other HMT330-series transmitters
Field check and adjust your transmitter using a HM70 humidity meter

Vaisala offers a 10-year warranty for new HMT331 transmitters that are calibrated annually at a Vaisala Service Center. Please see the details on our web page and the conditions of the 10-year warranty.

Analog outputs are preset at the factory to:

  • Channel 1: 4…20 mA = 0...100% RH
  • Channel 2: 4...20 mA = -40...+60°C (-40...+140°F) T

The package includes:

  • Calibration certificate (ISO9001 compliant, traceable)
  • M20x1.5 cable gland and NPT1/2" conduit fitting included to facilitate wiring
  • User's Guide in English

HMT331 Humidity and Temperature Transmitter for Wall Mounting, 1%RH accuracy
HMT330 series: The HMT331 Humidity Temperature Transmitter is ideal for data centers, museums and laboratories
Standard delivery time for single unit: 1 week
About delivery times »
Warranty: 24 months, extended to 10 years if calibrated annually at a Vaisala service center
About warranty »
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Detailed information

Measurement parameter(s)Relative humidity
Absolute humidity
Dew point temperature
Mixing ratio
Water vapor pressure
Wet bulb
Measurement range0 ... 100 % RH
-40 ... +60 °C (-40 ... +140 °F) T
Measurement accuracy±1.0 % RH (0 ... 90 % RH)
±1.7 % RH (90 ... 100 % RH)
±0.2 °C (±0.36 °F) T
Operating temperature-40 ... +60 °C (-40 ... +140 °F)
Operating voltage10 ... 35 VDC, 24 VAC ±20%
Analog outputs4 ... 20 mA (default setting)
0 ... 20 mA
0 ... 1 V
0 ... 5 V
0 ... 10 V
Digital outputsRS-232
Housing classificationIP65 (NEMA 4)
Links See full specifications on
Download user guides and other product documents on

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