The Vaisala HMT330 Series was a flagship industrial transmitter platform for humidity, temperature and calculated moisture parameters. It is discontinued and replaced by an Indigo500 transmitter with the HMP probe selected for the application.
Product status: The Vaisala HMT330 Series is discontinued. For a new installation or planned migration, use a Vaisala Indigo510 or Indigo520 transmitter with the appropriate Indigo-compatible HMP probe.
The Vaisala HMT330 Series combined an industrial transmitter enclosure with one of several application-specific humidity and temperature probes. It was used for wall mounting, ducts, environmental chambers, high-pressure processes, vacuum systems, ovens, dryers, continuously humid environments and pressurised pipelines.
The platform measured relative humidity and temperature and calculated parameters such as dew point, mixing ratio, absolute humidity, wet-bulb temperature, enthalpy and water-vapour pressure. Configuration-dependent outputs included analogue signals, RS-232, RS-485, relays and a local display.
| Legacy model | Original application | Current HMP probe | Current transmitter |
|---|---|---|---|
| HMT331 | Wall-mounted humidity and temperature measurement | Vaisala HMP1 | Indigo510 or Indigo520 |
| HMT333 | Duct mounting, chambers and restricted installation spaces | Vaisala HMP3 or Vaisala HMP9 | Indigo510 or Indigo520 |
| HMT334 | High-pressure processes up to 100 bar and vacuum conditions | Vaisala HMP4 | Indigo510 or Indigo520 |
| HMT335 | High-temperature ovens, dryers and industrial processes | Vaisala HMP5 | Indigo510 or Indigo520 |
| HMT337 | Continuous high humidity and meteorological applications | Vaisala HMP7 | Indigo510 or Indigo520 |
| HMT338 | Pressurised pipelines up to 40 bar | Vaisala HMP8 | Indigo510 or Indigo520 |
| Selection point | HMP3 | HMP9 |
|---|---|---|
| Main advantage | Field-maintainable general-purpose 12 mm probe | Compact 5 mm sensing head with fast response |
| Best fit | Ducts, chambers, paint booths, HVAC and industrial process air | Tight spaces and rapidly changing conditions |
| Temperature range | −40 to +120 °C at the probe head | −40 to +120 °C at the probe head |
| Maintenance approach | Replaceable filter and field-replaceable sensor option | Small probe selected where access and response are the priorities |
| Choose when | A robust general-purpose replacement and practical maintenance are required | The former installation has very limited clearance or needs faster response |
| Comparison point | HMT330 Series | Indigo500 with HMP probe |
|---|---|---|
| Product status | Discontinued | Current modular platform |
| Measurement architecture | Transmitter and model-specific probe supplied as one configured system | Interchangeable smart probe connected to a separate transmitter |
| Humidity accuracy | Up to ±1.0 %RH at +20 °C | Up to ±0.8 %RH with the applicable current HMP probe |
| Temperature accuracy | Up to ±0.2 °C at +20 °C | Up to ±0.1 °C with the applicable current HMP probe |
| Analogue output | Configuration-dependent current or voltage outputs | Isolated current or voltage outputs through Indigo510 or Indigo520 |
| Digital communication | RS-232 and optional RS-485 | Ethernet, Modbus TCP and browser-based interface; probe also supports Modbus RTU |
| Probe replacement | Legacy model-dependent service arrangement | Probe can be disconnected, calibrated or exchanged independently |
| Local interface | Optional legacy display and keypad | Optional modern touchscreen interface |
| Enclosure | IP65 industrial enclosure | IP66 and NEMA 4 metal enclosure |
| Requirement | Indigo510 | Indigo520 |
|---|---|---|
| Connected probes | One | Two simultaneously |
| Analogue outputs | Two isolated channels | Four isolated channels |
| Relays | Not included | Two configurable relays |
| Ethernet and Modbus TCP | Yes | Yes |
| Best fit | Premium single-probe replacement | Advanced control, dual-probe or multi-parameter installation |
Compare Vaisala Indigo510 and Indigo520 transmitters
Not automatically a drop-in replacement: the Indigo500 and HMP combination replaces the HMT330 measurement function, but enclosure dimensions, wiring terminals, probe connections, cable arrangements and output configuration may differ. Review the complete installation before ordering.
A functioning HMT330 does not need to be removed solely because the series is discontinued. Retain the model code, configuration records, wiring drawings, calibration certificates and user documentation while the instrument remains operational.
For critical measurements, check calibration and repair availability and plan migration before a failure creates an extended interruption. Replacement priority should consider instrument condition, calibration performance, spare availability and the effect of measurement downtime on the process.
Seacom Process Instruments supports existing Vaisala HMT330 humidity and temperature transmitters in Malaysia and supplies the current Indigo500 and HMP probe platform for industrial processes, chambers, high-humidity environments, high temperatures, vacuum systems and pressurised pipelines.
Our team can assist with identifying the correct replacement probe, selecting Indigo510 or Indigo520, reviewing process fittings and cable lengths, mapping analogue outputs and relays, planning Ethernet or Modbus integration, commissioning and calibration.
Contact Seacom with the complete HMT330 model code, application conditions, pressure and temperature range, existing outputs, power supply, process connection and installation photographs so we can recommend a practical migration arrangement.
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 HMP3 is a high-accuracy, field-maintainable probe for industrial HVAC, air-handling units, cleanrooms, paint booths and environmental chambers.
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 HMP8 provides high-accuracy humidity and temperature measurement in compressed air, refrigerant dryers and pressurised industrial processes up to 40 bar.
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 Indigo200 Series is the standard transmitter platform for one interchangeable Indigo-compatible smart probe, providing local display and practical automation-system connectivity.
The Vaisala Indigo500 Series provides flagship industrial measurement integration: choose Indigo510 for a simplified single-probe system or Indigo520 for full dual-probe capability.
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 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 HMD60 Series provides high-accuracy humidity and temperature measurement for demanding HVAC ducts and light-industrial applications.
The Vaisala Indigo200 Series is the standard transmitter platform for one interchangeable Indigo-compatible smart probe, providing local display and practical automation-system connectivity.
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 HMP3 is a high-accuracy, field-maintainable probe for industrial HVAC, air-handling units, cleanrooms, paint booths and environmental chambers.
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 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 HMM100 provides reliable humidity measurement and a configurable analog output for integration into environmental chambers and OEM equipment.
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 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 HMM105 provides reliable humidity measurement for integration into environmental chambers, incubators and OEM equipment.
The Vaisala HMP8 provides high-accuracy humidity and temperature measurement in compressed air, refrigerant dryers and pressurised industrial processes up to 40 bar.
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 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 Origo10 Series comprises modular HVAC transmitters with interchangeable probes for humidity, temperature, CO2 and dew-point measurement.
Available with analog, Modbus RTU and BACnet MS/TP outputs, wall or duct mounting, an optional display and an IP65-rated enclosure.
