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Vaisala HMT370EX & DMP370 Intrinsically Safe Humidity, Temperature and Dew Point Measurement
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.
- HMP probes for relative humidity and temperature
- DMP370 dew-point measurement from −70 to +10 °C Td/f
- Two two-wire 4–20 mA outputs
- Certified configurations for hazardous gas and dust areas, up to Zone 0 / 20
- Detachable probes and traceable calibration
DMP370 availability: Vaisala plans first deliveries for Q1 2027. Contact Seacom for configuration and project lead time.
Measuring moisture in a hazardous area starts with two questions: what needs to be measured, and where will the instrument be installed? A room-humidity application, a dry-gas pipeline and moisture measurement in oil require different probes, even when they use the same transmitter platform.
The Vaisala HMT370EX supports humidity and temperature measurement using HUMICAP® HMP probes. The new DMP370 intrinsically safe dew-point instrument combines a DMP37X DRYCAP® probe with the HMT370EX transmitter for measuring low dew point and trace moisture in gases.
Choose the Measurement Configuration
| Configuration | Main measurement | Selection focus |
|---|---|---|
| HMT370EX with HMP humidity probe | Relative humidity and temperature, with calculated humidity parameters. | Humidity control and monitoring in hazardous rooms, ducts and process environments. |
| DMP370: HMT370EX with DMP37X probe | Dew point and trace moisture in gases. | Dry-gas measurement where low moisture levels and hazardous-area certification are required. |
| HMT370EX with HMP378F | Moisture and temperature in oil. | Oil-moisture applications requiring a dedicated liquid-compatible probe. |
| HMT370EX with HMP378H | Moisture and temperature in JET A-1 fuel. | Aviation-fuel applications within the probe’s specified operating conditions. |
Selection note: A calculated dew-point output from an HMP humidity probe does not make it equivalent to a DMP370 low-dew-point configuration. Select the sensor against the expected moisture range and required accuracy.
New DMP370: Dew Point Measurement in Hazardous Locations
The DMP370 brings Vaisala DRYCAP® technology to hazardous-area gas measurement. Its drift-compensation approach supports continuous measurement without measurement gaps during compensation.
Applications include hydrogen production and storage, biomethane upgrading, natural-gas infrastructure, compressed air, nitrogen and purge-gas systems. It also supports suitable battery dry-process applications where combustible carbon dust may be present.
Availability: Announced in September 2026, with first deliveries planned by Vaisala for Q1 2027. Please confirm the required configuration and delivery schedule with Seacom.
Watch the Vaisala DMP370 Introduction
Watch DMP370 Technology Description
HMT370EX Video
DMP370 Measurement Specifications
| Parameter | Specification |
|---|---|
| Dew-point range | −70 to +10 °C Td/f |
| Dew-point accuracy | ±2 °C Td/f at +23 °C under the datasheet’s specified conditions; accuracy varies with measurement conditions. |
| Process temperature | −40 to +60 °C, subject to the selected probe and applicable installation limits. |
| Sensor technology | Vaisala DRYCAP® |
| Transmitter outputs | Two two-wire 4–20 mA outputs. |
| Pressure selection | Probe-dependent. Confirm the probe-head pressure rating and measurement-performance conditions for the actual process. |
DMP370 Probe Options
| Probe | Installation type |
|---|---|
| DMP371 | Wall-mounted measurement. |
| DMP374 | Pressurised spaces. |
| DMP375 | Long probe option for installations requiring greater reach. |
| DMP377 | Compact probe for restricted installation spaces. |
| DMP378 | Pressurised pipelines with adjustable insertion depth. |
DMP and HMP probes with similar model numbers do not necessarily share the same temperature range or measurement function. In particular, DMP375 is a long dew-point probe; the high-temperature capability of HMP375 must not be applied to it.
HMT370EX Humidity and Temperature Probe Options
For relative-humidity measurement, select an HMP probe according to the process temperature, pressure and installation arrangement.
| Probe | Typical selection |
|---|---|
| HMP371 | Wall mounting and ambient measurement. |
| HMP373 | Confined spaces, ducts and channels. |
| HMP374 | Pressurised spaces and vacuum applications. |
| HMP375 | High-temperature processes. |
| HMP377 | High-humidity applications. |
| HMP378 | Pressurised pipelines. |
The HMP humidity range includes probe options covering temperatures from −70 to +180 °C. These are probe-dependent limits, not a universal operating range for every configuration. HMP371 and HMP373 also have temperature-only ordering options.
Display, Calibration and Maintenance
- Local indication: graphical LCD and non-display configurations are available.
- Detachable probe module: probes can be removed for calibration outside the hazardous area without removing the entire transmitter.
- Configuration tools: Vaisala Insight PC software and compatible service accessories support configuration and maintenance.
- Calibration documentation: traceable calibration certificates support instrument records and maintenance planning.
For an existing HMT370EX installation, provide the transmitter serial number and current probe details before ordering a different probe type. Confirm compatibility and the approved system configuration before planning a change.
Hazardous-Area Installation and System Integration
Certified configurations support installation up to Zone 0 for gas and Zone 20 for dust. The exact certificate, temperature class and installation limits must match the ordered equipment and site classification.
The complete measurement loop must be assessed, including the intrinsic-safety barrier or isolator, power supply, cable parameters and process connection. Service connections and probe replacement must follow the applicable Vaisala instructions.
For central records and alarms, discuss connection of the 4–20 mA signals to a suitable monitoring system. A continuous monitoring system requires compatible inputs and an appropriately designed hazardous-area interface; it is not a direct network connection from the transmitter.
Discuss Your HMT370EX or DMP370 Application with Seacom
Send us the gas or liquid being measured, expected humidity or dew-point range, process temperature and pressure, hazardous-area classification, and required output. A process sketch or existing instrument model will help us review the probe and installation requirements.
Seacom Process Instruments can assist with measurement selection and quotation for projects in Malaysia, including new installations and replacement planning.
16 other products in the same category:
The Vaisala HMM105 provides reliable humidity measurement for integration into environmental chambers, incubators and OEM equipment.
- 0–100% RH measurement range
- I2C output for relative humidity or dew point
- Detachable 12 mm probe with 300 mm flexible cable
- Probe withstands +180 °C continuously and +200 °C temporarily
The Vaisala HMM170 provides accurate and stable humidity and temperature measurement for demanding environmental chambers, including vacuum and pressurised applications.
- Humidity accuracy up to ±1.0% RH
- Temperature measurement from −70 to +180 °C
- Modbus RTU and three configurable analog outputs
- Probe heating, sensor warming and chemical-purge options
The Vaisala GMW90 Series provides stable wall-mounted carbon-dioxide and temperature measurement, with optional humidity, for demanding HVAC and building-automation applications.
- Carbon-dioxide measurement from 0 to 5000 ppm
- CO₂ accuracy up to ±(30 ppm + 2% of reading)
- Temperature measurement from −5 to +55 °C
- Optional HUMICAP® relative-humidity measurement from 0 to 95 %RH
- Voltage, current or Modbus RTU output models
- Display and CO₂ status-indicator options
- Field-exchangeable calibrated measurement modules
- Traceable three-point CO₂ calibration certificate included
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 HMDW80 Series provides cost-effective humidity and temperature measurement for routine HVAC and building-automation applications.
- Humidity accuracy up to ±3% RH
- Wall, duct and outdoor installation models
- Current or voltage output configurations
- Replaceable INTERCAP® humidity sensor
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.
- Measures CH4, CO2 and water vapour in one probe
- 0–100 vol-% measurement range for methane and carbon dioxide
- Humidity output as 0–25 vol-% H2O or −10 to +60 °C dew point
- Heated optics help prevent condensation in wet biogas
- Three isolated 4–20 mA outputs and RS-485 Modbus RTU
- Ex-certified construction for direct installation in hazardous process areas
The Vaisala HMM100 provides reliable humidity measurement and a configurable analog output for integration into environmental chambers and OEM equipment.
- 0–100% RH measurement range
- Relative-humidity or dew-point output
- Current and voltage output options
- Plastic or stainless-steel probes for temperatures up to +180 °C
The Vaisala HMD60 Series provides high-accuracy humidity and temperature measurement for demanding HVAC ducts and light-industrial applications.
- Humidity accuracy up to ±1.5% RH
- Temperature accuracy up to ±0.1 °C
- Analog, Modbus RTU and BACnet MS/TP options
- Robust IP66 metal enclosure
The Vaisala HMT140 Wi-Fi Data Logger has been discontinued and is no longer recommended for new monitoring systems.
- Primary replacement: Vaisala RFL100 with AP10 VaiNet Access Point
- Existing HMT140 installations can continue to be supported
- Migration should be checked against the existing sensor and input type
- Contact Seacom for replacement selection and viewLinc compatibility
The Vaisala Indigo200 Series is the standard transmitter platform for one interchangeable Indigo-compatible smart probe, providing local display and practical automation-system connectivity.
- Indigo201 with three analog outputs and two relays
- Indigo202 with Modbus RTU and two relays
- Colour display with numerical and graphical views
- IP65 enclosure for industrial measurement applications
The Vaisala HMP7 is designed for continuously humid, rapidly changing and near-condensing environments. Probe heating helps prevent condensation while maintaining reliable process measurement.
- Humidity accuracy up to ±0.8% RH
- Probe heating for condensation prevention
- −70 to +180 °C probe-head measurement range
- Standalone Modbus RTU or Vaisala Indigo transmitter operation
The Vaisala HMP8 provides high-accuracy humidity and temperature measurement in compressed air, refrigerant dryers and pressurised industrial processes up to 40 bar.
- Humidity accuracy up to ±0.8% RH
- Operating pressure from vacuum to 40 bar
- Adjustable insertion depth with two probe lengths
- Optional ball valve for insertion and removal under process conditions
The Vaisala HMP4 provides high-accuracy humidity and temperature measurement in compressed air, breathing air, industrial gases, vacuum systems and other processes operating at pressures up to 100 bar.
- Operating pressure below 100 bar, including vacuum applications
- Humidity accuracy up to ±0.8% RH
- Temperature range from -70 °C to +180 °C
- Standalone Modbus RTU or connection to an Indigo transmitter
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.
The Vaisala HMP3 is a high-accuracy, field-maintainable probe for industrial HVAC, air-handling units, cleanrooms, paint booths and environmental chambers.
- Humidity accuracy up to ±0.8% RH
- Temperature measurement from −40 to +120 °C
- Field-replaceable filter and HUMICAP sensor option
- Standalone Modbus RTU or Vaisala Indigo transmitter operation
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.
- Legacy three-in-one pressure, humidity and temperature transmitter
- PTU301, PTU303, PTU304, PTU305, PTU307 and PTU308 variants
- Former applications include laboratories, meteorology and semiconductor measurement
- Current replacement platform: Indigo520 with barometric-pressure measurement
- Humidity probe selected according to mounting and process conditions
- Existing wiring, outputs and process connections require migration review