The Vaisala HMM170 provides accurate and stable humidity and temperature measurement for demanding environmental chambers, including vacuum and pressurised applications.
The Vaisala HUMICAP® HMM170 is a robust open-frame measurement module for integration into environmental chambers and OEM equipment. It is designed for applications requiring dependable humidity and temperature measurement across a wide operating range, including vacuum, elevated pressure, high humidity and chemically demanding conditions.
The module combines an external stainless-steel probe with an open-frame circuit board. This allows the probe to be positioned at the representative measurement point while the electronics are installed in a protected and serviceable location inside the equipment.
The HMM170 measures relative humidity from 0–100% RH and temperature from −70 to +180 °C. At normal room temperature, relative-humidity accuracy reaches ±1.0% RH from 0–90% RH.
In addition to relative humidity and temperature, the module calculates dew point, wet-bulb temperature, enthalpy, mixing ratio, water-vapour pressure and other humidity parameters. Measurement values can be transferred to the chamber controller through Modbus RTU or up to three configurable analog outputs.
Environmental chambers may expose humidity sensors to prolonged high humidity, condensation, cleaning agents and chemical vapours. The HMM170 provides optional functions that help maintain measurement availability and long-term stability under these conditions.
The required heating function and humidity sensor should be selected according to the chamber atmosphere. Available sensor options support general humidity measurement, vaporised hydrogen peroxide environments and moisture-in-oil applications.
The HMM170 provides an RS-485 interface with Modbus RTU and three freely configurable analog output channels. It can supply several measurement parameters to the chamber controller without requiring a separate external transmitter.
An integrated service port allows connection to Vaisala Insight PC software for configuration, diagnostics, temporary live monitoring, calibration and adjustment. Probe cable options of 2, 5 and 10 metres support different chamber layouts and electronics-compartment locations.
The HMM170 circuit-board footprint also supports practical upgrades from many existing HMM100 installations. Electrical connections, outputs, mechanical dimensions and controller programming should still be checked before replacement.
All three modules are designed for integration into environmental chambers or OEM equipment. The correct model depends mainly on the controller interface, required outputs, chamber conditions and maintenance functions.
| Selection point | Vaisala HMM100 | Vaisala HMM105 | Vaisala HMM170 |
|---|---|---|---|
| Best suited for | Conventional chambers requiring one analog measurement output | OEM chambers and incubators with direct I2C controller integration | Demanding chambers requiring higher accuracy, multiple outputs or condensation protection |
| Measured parameters | Relative humidity or dew point | Relative humidity or dew point | Relative humidity, temperature, dew point and other calculated parameters |
| Humidity range | 0–100% RH | 0–100% RH | 0–100% RH |
| RH accuracy at −20 to +40 °C | ±2% RH from 0–90% RH | ±2% RH from 0–90% RH | Approximately ±1.0 to ±1.7% RH, depending on temperature and RH |
| Primary output | One configurable current or voltage output | Digital I2C | Modbus RTU and three configurable analog outputs |
| Probe temperature capability | Up to +180 °C, depending on probe and filter | Up to +180 °C continuously; +200 °C short-term peak | −70 to +180 °C |
| Probe arrangement | Plastic or stainless-steel probe with several cable and length options | Detachable 12 mm probe with fixed 300 mm flexible cable | 12 mm stainless-steel probe with 2, 5 or 10 m cable options |
| Condensation and chemical protection | Standard HUMICAP measurement without active probe heating | Standard HUMICAP measurement without active probe heating | Optional sensor purge, probe heating and sensor warming |
| Configuration and servicing | Service port and on-board adjustment trimmers | Configuration and adjustment through the I2C interface | Vaisala Insight software through the integrated service port |
Quick selection: choose HMM100 when the chamber controller needs a conventional analog signal. Choose HMM105 when direct I2C communication and a compact detachable probe are required. Choose HMM170 for demanding installations needing improved accuracy, Modbus RTU, several analog outputs, longer probe cables or active condensation protection.
Before selecting the HMM170, confirm the chamber temperature and humidity range, operating pressure, expected condensation, chemical exposure, probe-cable length, required measurement parameters, controller inputs and preferred communication interface.
For retrofit projects, provide the existing module model, output configuration, wiring details, probe installation and controller scaling. This allows the mechanical and electrical requirements to be checked before replacing an HMM100 or another chamber sensor.
Seacom Process Instruments supplies and supports the Vaisala HMM170 Humidity and Temperature Module in Malaysia for environmental chambers, stability chambers, climatic test equipment, incubators and demanding OEM measurement systems.
Our team can assist with humidity-sensor selection, probe heating, sensor purge, cable length, output configuration, Modbus integration, installation planning, commissioning and calibration support.
Contact Seacom with your chamber operating range, pressure, chemical exposure, condensation conditions, controller interface and required outputs so we can recommend a suitable HMM170 configuration.
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