The Vaisala HMP155 provides stable humidity and temperature measurement for automatic weather stations, road-weather systems, airports, research sites and demanding outdoor monitoring.
The Vaisala HUMICAP® HMP155 is designed for accurate and stable outdoor humidity and temperature measurement. Its weather-resistant probe construction, protective filter options and long-term measurement stability make it suitable for professional meteorology and other exposed environmental-monitoring locations.
Typical installations include automatic weather stations, airport observation systems, road-weather stations, agricultural research, hydrology sites, environmental-monitoring networks and industrial locations requiring meteorological-grade outdoor measurements.
| Model | Humidity output | Temperature output | Recommended use |
|---|---|---|---|
| HMP155A | Analogue voltage | Analogue voltage | Data loggers and weather stations requiring two active voltage signals |
| HMP155D | Analogue voltage | Passive four-wire Pt100 | Systems that read RH as voltage and temperature directly from a precision resistance input |
| HMP155E | RS-485 digital | RS-485 digital | Digital data-acquisition systems requiring serial measurement data |
Selection point: all HMP155 models have an RS-485 interface for service use, but HMP155E is the model intended to provide RS-485 as its measurement output. Select the complete model and output configuration according to the receiving data logger or weather-station controller.
| Measurement specification | Performance |
|---|---|
| Relative-humidity range | 0 to 100 %RH |
| RH accuracy at +15 to +25 °C | ±1 %RH from 0 to 90 %RH; ±1.7 %RH from 90 to 100 %RH |
| Factory-calibration uncertainty at +20 °C | ±0.6 %RH from 0 to 40 %RH; ±1.0 %RH from 40 to 95 %RH |
| Humidity sensor | HUMICAP® R2, HUMICAP® 180R or configuration-dependent equivalent; composite versions for purge or warming |
| Temperature observation range | −80 to +60 °C |
| Temperature sensor | Pt100 RTD, Class F0.1 according to IEC 60751 |
| Operating voltage | 7 to 28 V DC; required minimum depends on output and heating options |
| Ingress protection | IP66 |
| Probe dimensions | Approximately 279 × 40 mm |
Fog, rain, heavy dew and near-saturated air can wet an unheated humidity sensor and temporarily prevent it from representing the surrounding atmosphere. The optional warmed-probe function keeps the sensor head above the ambient dew-point temperature, reducing the risk of condensation on the sensing element.
Because warming changes the temperature at the humidity sensor, accurate ambient relative humidity is calculated using a separate temperature measurement. Select the warmed-probe and additional-temperature-sensor arrangement together rather than treating probe heating as an independent accessory.
Optional chemical purge periodically heats the humidity sensor to reduce the effect of certain chemical contaminants. This is useful where long-term stability may be challenged by airborne chemicals, but it does not replace correct siting, filter selection, inspection or calibration.
A sintered PTFE filter provides strong protection against water, dust and dirt. A membrane filter can provide faster response where the application and exposure conditions allow it. Filter condition should be checked during scheduled weather-station maintenance.
| Installation option | Purpose | Selection guidance |
|---|---|---|
| DTR503 | Natural-aspiration radiation shield for HMP155 installations | Common choice for automatic weather stations and exposed monitoring sites |
| DTR13 | Compact radiation shield for compatible probe installations | Use where its mounting arrangement and measurement requirements are suitable |
| Stevenson screen | Traditional naturally ventilated instrument enclosure | Suitable where the observation standard or existing station design requires it |
| DTR502 with additional-temperature-probe kit | Shielding of the separate temperature sensor | Used with applicable warmed-probe configurations requiring independent ambient temperature |
Radiation shielding is essential for representative outdoor temperature and humidity measurement. The shield must protect the sensor from precipitation and direct or reflected solar radiation while allowing sufficient airflow around the probe.
| Selection point | HMP155 | Industrial HMP probe |
|---|---|---|
| Primary role | Meteorological and exposed outdoor measurement | Industrial process, duct, chamber or pipeline measurement |
| Typical installation | Radiation shield, weather station or environmental-monitoring mast | Process fitting, duct kit, chamber or Indigo transmitter |
| Temperature environment | Outdoor operation down to −80 °C, up to +60 °C | Application-dependent probes covering general, high-temperature, high-humidity and pressurised processes |
| Outputs | Voltage, passive Pt100 or RS-485 according to HMP155 model | Standalone Modbus RTU or connection to an Indigo transmitter, depending on probe |
| High-humidity strategy | Optional warmed probe with additional ambient-temperature measurement | Vaisala HMP7 for continuously humid industrial processes |
Seacom Process Instruments supplies and supports the Vaisala HMP155 meteorological humidity and temperature probe in Malaysia for automatic weather stations, airports, road-weather systems, research sites, plantations and environmental-monitoring networks.
Our team can assist with choosing HMP155A, HMP155D or HMP155E, selecting warmed-probe and chemical-purge options, matching the radiation shield, reviewing power and output requirements, planning installation and arranging calibration.
Contact Seacom with your temperature and humidity range, required output, data-logger input, site exposure, shield preference, cable length and calibration requirements so we can recommend a suitable HMP155 configuration.
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Product transition: HMT120/HMT130 are expected to be phased out. For new projects, the Vaisala Origo10 is the recommended replacement platform.
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DMP370 availability: Vaisala plans first deliveries for Q1 2027. Contact Seacom for configuration and project lead time.
The Vaisala HMP110 is a high-accuracy humidity and temperature probe designed for demanding equipment integration, environmental chambers, data loggers, incubators and controlled-environment applications.
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The Vaisala HMM170 provides accurate and stable humidity and temperature measurement for demanding environmental chambers, including vacuum and pressurised applications.
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The Vaisala HMD60 Series provides high-accuracy humidity and temperature measurement for demanding HVAC ducts and light-industrial applications.
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It provides 0–100% RH and −40 °C to +60 °C measurement ranges, low power consumption, interchangeable Vaisala INTERCAP sensor and optional Modbus RTU communication.
The Vaisala XMP10 Series comprises compact humidity and temperature probes offering accuracy levels up to ±1% RH and ±0.1 °C for demanding HVAC, data-centre and critical-environment applications.
The probes feature analog or Modbus RTU outputs, a standard M8 connector, an IP65-rated body and compatibility with Vaisala Origo10 modular HVAC transmitters.
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The Vaisala Indigo520 Supervisor manages up to 100 compatible compact humidity and temperature probes through one host unit. It provides local visibility for the maintenance team and Modbus TCP communication for data centre BMS integration.
Expected availability: early 2027. Enquire with Seacom for configuration and delivery confirmation.
The Vaisala HMX110 Series provides accurate humidity and temperature measurement for demanding indoor, duct and outdoor HVAC applications.
The Vaisala HMP9 combines a miniature 5 mm probe head with fast-response, high-accuracy humidity and temperature measurement for tight spaces and rapidly changing environments.
The Vaisala HMM105 provides reliable humidity measurement for integration into environmental chambers, incubators and OEM equipment.
