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.
The Vaisala HMM100 provides reliable humidity measurement and a configurable analog output for integration into environmental chambers and OEM equipment.
The Vaisala PTU300 combined barometric pressure, relative humidity and temperature in one transmitter. The series is discontinued and has been replaced by a suitable Indigo520 barometric-pressure configuration with an application-specific HMP probe.
The Vaisala HMP5 provides high-accuracy humidity and temperature measurement in ovens, dryers, kilns and other processes operating at temperatures up to +180 °C.
The Vaisala MGP261 measures methane, carbon dioxide and humidity directly in raw biogas. Its in-situ design avoids a separate sampling system and helps operators monitor gas quality while protecting downstream equipment.
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.
It provides ±1.5% RH accuracy, a 0–100% RH range, −40 °C to +80 °C temperature measurement, a chemically resistant HUMICAP 180R sensor and analog or Modbus RTU output options.
The Vaisala HMT370EX provides intrinsically safe humidity and temperature measurement with HMP-series probes. The new DMP370 configuration combines the HMT370EX transmitter with a DMP37X DRYCAP® probe for low-dew-point measurement in hazardous locations.
DMP370 availability: Vaisala plans first deliveries for Q1 2027. Contact Seacom for configuration and project lead time.
The Vaisala HMT360 Series was an intrinsically safe transmitter platform for humidity, temperature and moisture measurement in hazardous areas. It is discontinued and replaced by the Vaisala HMT370EX with an application-specific probe.
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 HMDW80 Series provides cost-effective humidity and temperature measurement for routine HVAC and building-automation applications.
The Vaisala Indigo300 is a rugged industrial transmitter for one Vaisala Indigo-compatible smart probe, providing local measurement display and up to three configurable analog outputs.
Its corrosion-resistant IP66 metal enclosure, flexible probe mounting and interchangeable probe design make Indigo300 suitable for humidity, temperature, dew point, CO2, moisture in oil and other demanding industrial measurements.
The Vaisala HMP7 is designed for continuously humid, rapidly changing and near-condensing environments. Probe heating helps prevent condensation while maintaining reliable process measurement.
The Vaisala HMP60 is a compact, durable and cost-effective humidity and temperature probe for equipment integration, data loggers, incubators, glove boxes, greenhouses and environmental monitoring systems.
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 XMW85 Series provides reliable indoor CO2, humidity and temperature measurement for demand-controlled ventilation, smart buildings and indoor air-quality monitoring.
All models support Modbus RTU over RS-485, with two-in-one and three-in-one measurement configurations and optional metric or non-metric displays.
The Vaisala HMM105 provides reliable humidity measurement for integration into environmental chambers, incubators and OEM equipment.
The Vaisala HMT120 and HMT130 provide accurate, stable humidity and temperature measurement for cleanrooms, laboratories, data centres and demanding HVAC applications.
Product transition: HMT120/HMT130 are expected to be phased out. For new projects, the Vaisala Origo10 is the recommended replacement platform.
The Vaisala Indigo500 Series provides flagship industrial measurement integration: choose Indigo510 for a simplified single-probe system or Indigo520 for full dual-probe capability.
