The wall-mounted Vaisala HMW90 Series provides high-accuracy humidity and temperature measurement for demanding HVAC, data-centre, laboratory, museum and warehouse environments.
The Vaisala HMW90 Series consists of high-performance wall-mounted humidity and temperature transmitters for indoor HVAC and building-automation applications that require excellent accuracy, long-term stability and dependable operation.
With humidity accuracy up to ±1.7% RH, temperature accuracy of ±0.2 °C within the specified central range, analog and Modbus RTU output options, and an exchangeable measurement module, the HMW90 is well suited to data centres, laboratories, museums, archives, production facilities, warehouses and testing environments.
The product family includes humidity-and-temperature models, temperature-only models, visible-display versions and customised configurations. The correct model can therefore be selected according to the required output signal, display, relay and measured parameters.
| Model | Measurement | Output and Features |
|---|---|---|
| HMW92 | Relative humidity and temperature | Two 4–20 mA current outputs; display hidden by the sliding cover |
| HMW92D | Relative humidity and temperature | Two 4–20 mA current outputs with visible display |
| HMW93 | Relative humidity and temperature | Two 0–5 V or 0–10 V outputs, relay and display hidden by the sliding cover |
| HMW93D | Relative humidity and temperature | Two 0–5 V or 0–10 V outputs, relay and visible display |
| HMW95 | Relative humidity and temperature | Isolated RS-485 Modbus RTU; display hidden by the sliding cover |
| HMW95D | Relative humidity and temperature | Isolated RS-485 Modbus RTU with visible display |
| HMW90 | Relative humidity and temperature | Factory-configurable analog or Modbus RTU model with selected parameter scaling |
| TMW92 | Temperature only | One 4–20 mA current output |
| TMW93 | Temperature only | One 0–5 V or 0–10 V output with relay |
| TMW90 | Temperature only | Factory-configurable analog-output model |
| Specification | Performance |
|---|---|
| Measurement Range | 0–100% RH, non-condensing |
| Accuracy at +10 °C to +40 °C, 0–90% RH | ±1.7% RH |
| Accuracy at +10 °C to +40 °C, 90–100% RH | ±2.5% RH |
| Accuracy at -5 °C to +10 °C and +40 °C to +55 °C, 0–90% RH | ±3% RH |
| Accuracy at -5 °C to +10 °C and +40 °C to +55 °C, 90–100% RH | ±4% RH |
| Typical HVAC Stability | ±0.5% RH per year |
| Humidity Sensor | Vaisala HUMICAP 180R |
| Specification | Performance |
|---|---|
| Measurement Range | -5 °C to +55 °C |
| Accuracy at +20 °C to +30 °C | ±0.2 °C |
| Accuracy at +10 °C to +20 °C and +30 °C to +40 °C | ±0.3 °C |
| Accuracy at -5 °C to +10 °C and +40 °C to +55 °C | ±0.5 °C |
| Temperature Sensor | Digital temperature sensor |
Depending on the selected HMW90 configuration, the transmitter can provide humidity values beyond relative humidity and temperature.
| Parameter | Typical Use |
|---|---|
| Dew Point | Indicates the temperature at which condensation may begin |
| Mixing Ratio | Represents the mass of water vapour relative to dry air |
| Enthalpy | Supports HVAC energy and air-treatment calculations |
| Wet-Bulb Temperature | Supports evaporative-cooling and psychrometric analysis |
| Dew-Point Depression | Shows the difference between ambient temperature and dew point |
| Absolute Humidity | Expresses the amount of water vapour per unit volume |
| Output Version | Technical Details |
|---|---|
| Current Output | Two loop-powered 4–20 mA outputs for HMW92 models |
| Current-Output Loop Resistance | 0–600 Ω |
| Current-Output Supply | 10–28 V DC at 0 Ω load; 20–28 V DC at 500 Ω load |
| Current-Channel Isolation | 500 V DC between output channels |
| Voltage Output | Two 0–5 V or 0–10 V outputs for HMW93 models |
| Voltage-Output Load | Minimum 10 kΩ |
| Voltage-Model Supply | 18–35 V DC or 24 V AC ±20%, 50/60 Hz |
| Relay | One relay on voltage-output models, maximum 50 V DC or 50 V AC, 500 mA |
| Feature | Specification |
|---|---|
| Digital Interface | Isolated RS-485 |
| Protocol | Modbus RTU |
| Modbus Address Range | 1–247 |
| End-of-Line Termination | 120 Ω termination enabled with a jumper |
| Supply Voltage | 18–35 V DC or 24 V AC ±20%, 50/60 Hz |
| Galvanic Isolation | 1.5 kV |
The HMW90 is suitable for demanding data-centre room measurements where stable humidity and temperature information is required by the building-management or data-centre infrastructure-management system.
For a broader overview, see our Vaisala Data Centre Environmental Monitoring Guide.
The sliding enclosure cover provides access to the adjustment controls and service connection without removing the transmitter from the wall.
| Specification | Value |
|---|---|
| Operating Temperature | -5 °C to +55 °C |
| Storage Temperature | -30 °C to +60 °C |
| Maximum Wire Size | 2 mm² or AWG 14 |
| Service-Port Connector | Four-pin M8 |
| Approximate Cover Dimensions | 132.7 × 81 × 30 mm |
| Colour Options | Standard white or black for configurable HMW90 and TMW90 models |
| Requirement | Recommended Model |
|---|---|
| 4–20 mA humidity and temperature outputs | HMW92 or HMW92D |
| 0–5 V or 0–10 V outputs | HMW93 or HMW93D |
| Relay with analog voltage outputs | HMW93 or HMW93D |
| Modbus RTU communication | HMW95 or HMW95D |
| Visible local display | Select the D version of HMW92, HMW93 or HMW95 |
| Temperature-only measurement | TMW92, TMW93 or configurable TMW90 |
| Special analog scaling or calculated parameter | Factory-configured HMW90 |
Seacom Process Instruments supplies and supports the Vaisala HMW90 Series humidity and temperature transmitters in Malaysia.
Our team can assist with model selection, output type, display option, calculated parameter, relay configuration, Modbus integration, installation location and calibration planning.
Contact Seacom with your required humidity and temperature range, output signal, building-automation interface and application conditions for a suitable HMW90 configuration.
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