Vaisala HMT360 Intrinsically Safe Humidity and Temperature Transmitter – Discontinued

Vaisala HMT360 Intrinsically Safe Humidity and Temperature Transmitter

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.

  • HMT361 wall mounting → HMP371
  • HMT363 ducts and confined spaces → HMP373
  • HMT364 high pressure and vacuum → HMP374
  • HMT365 high temperature → HMP375
  • HMT367 high humidity → HMP377
  • HMT368 pressurised pipelines → HMP378

Product status: The Vaisala HMT360 Series is discontinued. For new hazardous-area installations and planned migrations, use the Vaisala HMT370EX intrinsically safe transmitter with the probe and regional certification selected for the application.

Vaisala HMT360 for Existing Hazardous-Area Installations

The Vaisala HMT360 Series provided intrinsically safe humidity and temperature measurement for potentially explosive gas and dust environments. Different probe versions supported wall mounting, confined spaces, high pressure, vacuum, high temperature, high humidity and pressurised pipelines.

Configuration-dependent versions also measured moisture in industrial oil, JET A-1 fuel and natural gas. The transmitter used two-wire 4–20 mA measurement channels through an approved intrinsic-safety interface, with service communication used for configuration and calibration.

HMT360 to HMT370EX Replacement Guide

Legacy modelOriginal applicationCurrent HMT370EX probeMigration note
HMT361 Wall-mounted ambient measurement HMP371 Fixed probe for wall or enclosure installation
HMT363 Ducts, channels and confined spaces HMP373 Check probe cable material, insertion depth and temperature class
HMT364 High-pressure processes and vacuum HMP374 Confirm process pressure, fitting and safe isolation arrangement
HMT365 High-temperature processes HMP375 Check probe-head temperature against the required Ex temperature class
HMT367 Continuous high humidity and demanding wet conditions HMP377 Review probe heating and external temperature compensation requirements
HMT368 Pressurised pipelines HMP378 Confirm insertion depth, fitting body and ball-valve arrangement

Explore the Vaisala HMT370EX replacement platform

Special HMT360 Moisture and Natural-Gas Versions

Legacy configurationOriginal medium or useCurrent starting pointImportant requirement
HMT368F / HMT360F Moisture in industrial oil HMT370EX with HMP378F Confirm oil type, water-solubility coefficients, process fitting and certification
HMT368H / HMT360H Moisture in JET A-1 fuel HMT370EX with HMP378H Confirm aviation-fuel application, installation and applicable approval
HMT362N Natural gas with a flanged probe arrangement Application review required Do not assume a current standard probe duplicates the legacy flange and certification
HMT364N High-pressure natural gas HMT370EX with HMP374 as the technical starting point Gas compatibility, pressure, process sealing and hazardous-area approval must be confirmed
HMT368N Natural-gas pipeline installation HMT370EX with HMP378 as the technical starting point Confirm gas service, pipeline pressure, insertion method, fitting and certification

Special-medium warning: a similar probe shape or pressure rating does not by itself approve a replacement for natural gas, oil or aviation fuel. The measured medium, complete Ex marking, sealing materials, pressure boundary and regional certification must be reviewed for the exact ordered configuration.

HMT360 and HMT370EX Comparison

Comparison pointHMT360 SeriesHMT370EX Series
Product status Discontinued Current replacement platform
Safety concept Intrinsically safe legacy transmitter Current intrinsically safe Ex i transmitter
Probe options HMT361, HMT363, HMT364, HMT365, HMT367 and HMT368 variants Interchangeable HMP371, HMP373, HMP374, HMP375, HMP377 and HMP378 probes
Special moisture versions Oil, JET A-1 and selected natural-gas configurations HMP378F for oil and HMP378H for JET A-1; natural gas requires application review
Relative-humidity range 0 to 100 %RH 0 to 100 %RH within model and dew-point limitations
Best stated RH accuracy Up to ±1.0 %RH at +20 °C Up to ±0.8 %RH at +23 °C
Temperature measurement Probe-dependent, up to −70 to +180 °C Probe- and certification-dependent, up to −70 to +180 °C
Analogue outputs Two-wire 4–20 mA, configuration-dependent Two configurable two-wire 4–20 mA channels
Probe servicing Legacy removable-probe arrangement Interchangeable smart probes with independent calibration
Ingress protection IP65 legacy enclosure Up to IP66 with the probe connected; configuration-dependent

Hazardous-Area Migration Checks

Replacing an intrinsically safe transmitter requires more than matching the measured parameter. Review the complete electrical and mechanical installation before changing the device.

  • Record the complete HMT360 model code, Ex marking and certification documents.
  • Confirm the gas or dust zone, gas group, dust group and required equipment protection level.
  • Check the required temperature class and maximum ambient and process temperatures.
  • Verify the safety barrier or galvanic isolator against the HMT370EX entity parameters.
  • Include field-cable capacitance, inductance and cable length in the intrinsic-safety assessment.
  • Confirm whether one or two 4–20 mA measurement channels are required.
  • Map the existing measurement ranges, engineering units and receiving-system scaling.
  • Check probe fitting, pressure rating, insertion depth, sealing materials and removal procedure.
  • Select the correct regional certificate for the country where the equipment will be installed.

Probe Temperature and Ex Temperature Class

The maximum measuring range of a probe is not automatically the permitted temperature in every hazardous-area installation. The allowed temperature depends on the probe model, cable material, gas or dust classification and required Ex temperature class.

Example temperature classPublished upper probe-head limit for applicable configurationsSelection guidance
T6 Approximately +55 °C Use the exact limit stated in the regional safety guide and ordered configuration
T5 Approximately +100 °C Applicable probe and cable configuration must be confirmed
T4 Up to approximately +135 °C for applicable remote probes Do not use the general probe range as the certified limit
T3 Up to +180 °C for applicable probe configurations Confirm the complete Ex approval, ambient conditions and installation method

Can an Existing HMT360 Remain in Service?

A functioning HMT360 does not need to be removed solely because the series is discontinued. Keep the transmitter label, probe model, barrier information, control drawing, wiring diagram, calibration certificates and configuration records while the installation remains in service.

For a critical hazardous-area measurement, check calibration and repair availability and plan migration before a failure creates an extended process interruption. Any service work must preserve the approved intrinsic-safety installation and be carried out by suitably competent personnel.

Vaisala HMT360 Support and HMT370EX Replacement in Malaysia

Seacom Process Instruments supports existing Vaisala HMT360 intrinsically safe transmitters in Malaysia and supplies the current HMT370EX platform for chemical production, pharmaceuticals, paint booths, powder handling, fuel storage, oil and gas processes and other hazardous areas.

Our team can assist with identifying the legacy probe, selecting the HMT370EX configuration, reviewing process fittings and pressure limits, mapping 4–20 mA outputs, coordinating safety barriers, commissioning and calibration planning.

Contact Seacom with the complete HMT360 model code, nameplate photographs, hazardous-area classification, measured medium, process temperature and pressure, existing barrier details and required outputs so we can review a suitable migration arrangement.

Download

  HMT370EX Series Catalogue   (1.11M)

  HMT360 Series Catalogue   (521.12k)

  HMT360 Order Form   (825.68k)


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