Vaisala DMT340 Dew Point and Temperature Transmitter – Discontinued

Vaisala DMT340 Dew Point and Temperature Transmitter Series

The Vaisala DMT340 Series provided configurable dew-point and temperature measurement for industrial low-humidity applications. The series is discontinued and replaced by Vaisala Indigo500 transmitters with DMP7 or DMP8 smart probes.

  • Former models: DMT341, DMT342, DMT344, DMT347 and DMT348
  • Designed for dry rooms, industrial dryers, compressed air and process gases
  • Legacy display, data logging, analog, relay and communication options
  • Use DMP7 for compact, wall-mounted or tight-space applications
  • Use DMP8 for pressurised processes and pipelines
  • Pair the selected probe with an Indigo500 transmitter

Product status: The Vaisala DMT340 Series is discontinued. For new projects and replacement planning, Vaisala recommends an Indigo500 Series transmitter with a DMP7 or DMP8 dew-point probe, selected according to the former DMT340 probe model and installation.

Vaisala DMT340 Series for Existing Installations

The Vaisala DMT340 Series was a configurable platform for continuous dew-point and temperature measurement in demanding low-humidity processes. Different probe constructions allowed the transmitter to serve dry rooms, industrial drying, compressed-air systems, semiconductor equipment, process gases and pressurised pipelines.

The transmitter could be configured with a local graphical display, analog outputs, alarm relays, data logging and digital communication. Because these functions and the mechanical probe arrangement varied by order code, a replacement must be based on the complete installed configuration rather than the DMT340 family name alone.

Current Replacement for Each DMT340 Model

Legacy modelOriginal installationCurrent starting pointReplacement note
DMT341 Wall-mounted probe for low-humidity spaces DMP7 + Indigo500 Review mounting position, cable length and required measurement range
DMT342 Small flanged probe, commonly used with a sampling arrangement DMP7 + Indigo500, subject to application review Vaisala's current mapping does not name a direct DMT342 equivalent; confirm the flange and sampling-cell arrangement
DMT344 Pressure-tight probe for pressurised processes DMP8 + Indigo500 Confirm pressure rating, thread, insertion depth and whether removal under pressure is required
DMT347 Small pressure-tight probe for compact installations DMP7 + Indigo500 Check the mechanical connection and available installation space carefully
DMT348 Adjustable probe for pressurised pipelines DMP8 + Indigo500 DMP8 provides adjustable insertion depth and supports an optional ball-valve installation

Correction for DMT344: use the dew-point probe DMP8 as the current comparison for pressurised DMT344 applications. HMP4 is a humidity-and-temperature probe and should not be presented as the standard DMT344 dew-point replacement.

DMP7 or DMP8?

Selection pointDMP7DMP8
Best fit Tight spaces, remote installations, dry rooms and compact equipment Pressurised pipelines and industrial compressed-air systems
Probe construction Short remote probe connected by cable Long probe with adjustable insertion depth
Pressure capability Application-dependent remote installation; review the process connection Up to 40 bar absolute
Removal from a pressurised line Requires an application-specific isolation arrangement Optional ball-valve kit permits insertion and removal using the specified procedure
Standalone communication Modbus RTU over RS-485 Modbus RTU over RS-485
Transmitter compatibility Indigo200, Indigo300 and Indigo500 families Indigo200, Indigo300 and Indigo500 families
Portable use Compatible with Indigo80 Compatible with Indigo80

Explore the Vaisala DMP7 for tight spaces

Explore the Vaisala DMP8 for pressurised pipelines

Other Vaisala DMP Dew Point Probes Available from Seacom

The wider Vaisala Indigo-compatible DMP family covers dry rooms, high-temperature processes, tight installations and pressurised pipelines. These probes are not interchangeable solely by measurement range; select according to the process temperature, pressure, mounting and required insertion arrangement.

ProbeMain strengthTypical applicationSeacom product page
DMP1 Fixed probe for room and wall installations Battery dry rooms, semiconductor areas and controlled low-humidity spaces View Vaisala DMP1
DMP5 Long probe for processes up to +180 °C Ovens, dryers and high-temperature industrial processes View Vaisala DMP5
DMP6 Passive cooling for processes up to +350 °C Very-high-temperature ovens, furnaces and industrial drying View Vaisala DMP6
DMP7 Short remote probe for limited installation space Tight equipment, dry rooms, semiconductor tools and remote installations View Vaisala DMP7
DMP8 Adjustable insertion into pressurised pipelines Compressed air, industrial gases and pressurised low-humidity processes View Vaisala DMP8

For a DMT340 replacement: Vaisala specifically directs the former DMT341 and DMT347 applications towards DMP7, and the former DMT344 and DMT348 applications towards DMP8. DMP1, DMP5 and DMP6 serve different mounting or temperature requirements and should only be selected after reviewing the application.

Why Use an Indigo500 Transmitter?

The Indigo platform separates the measurement probe from the display and system-interface transmitter. The DMP probe contains the measurement intelligence and calibration data, while the Indigo500 transmitter provides local indication, outputs, relays, data handling and network access according to the selected model.

FunctionIndigo510Indigo520
Probe inputs One compatible probe Two compatible probes
Analog outputs Two configurable and isolated channels Four configurable and isolated channels
Relays Not included Two configurable relays
Ethernet Web interface and Modbus TCP Web interface and Modbus TCP
Enclosure Rugged IP66 / NEMA 4 metal housing Rugged IP66 / NEMA 4 metal housing
Typical selection Single-probe installation with straightforward system outputs Dual-probe, relay or more extensive output requirements

Compare Vaisala Indigo510 and Indigo520 transmitters

DMT340 and Indigo Migration Considerations

Migration itemWhat to verify
Legacy probe model Identify whether the installed unit is DMT341, DMT342, DMT344, DMT347 or DMT348
Mechanical installation Thread, flange, insertion depth, pressure seal, sampling cell and isolation method
Measurement range Required dew point, frost point, temperature and calculated parameters
Analog outputs Signal type, scaling, number of channels and galvanic isolation
Digital communication Existing serial or Ethernet protocol, register mapping and receiving-system configuration
Alarm functions Relay quantity, alarm logic, set points, delays and fail-safe behaviour
Power supply Available AC or DC supply and existing wiring
Data logging Required history, trends, export and time synchronisation
Physical replacement Wall space, cable entry and use of an Indigo adapter plate for the former transmitter location

An Indigo adapter plate can simplify mounting at a former DMT340 transmitter location, but it does not eliminate the need to review wiring, probe installation and system configuration.

Existing DMT340 Installations

For an operating DMT340, retain the complete order code, probe model, output scaling, relay settings, communication configuration, calibration certificates and installation drawings. These records are essential for service work and for specifying a suitable Indigo replacement.

Product discontinuation does not by itself require immediate removal of a functioning transmitter. Plan replacement around calibration status, spare availability, maintenance risk, shutdown access and the importance of the measurement to the process.

Vaisala DMT340 Support and Indigo Migration in Malaysia

Seacom Process Instruments supports existing Vaisala DMT340 Series installations in Malaysia and supplies current Indigo500, DMP7 and DMP8 configurations for dry rooms, compressed air, industrial drying, semiconductor manufacturing and pressurised low-humidity processes.

Our team can assist with legacy model identification, process connections, probe selection, Indigo510 or Indigo520 configuration, analog and digital integration, relay requirements, mounting arrangements, commissioning and calibration planning.

Contact Seacom with the complete DMT340 order code, application, operating pressure and temperature, dew-point range, mechanical connection, outputs and communication requirements so we can assess the correct Indigo replacement configuration.

Download

  DMP6 Catalogue   (194.41k)

  DMP5 Catalogue   (175.49k)

  DMP7 Catalogue   (180.16k)

  DMP8 Catalogue   (197.59k)

  Indigo200 Catalogue   (204.62k)

  Indigo 500 Catalogue   (581.96k)

  DMT340 Series Catalogue   (489.31k)

  DMT340 Order Form   (569.82k)

  DMP7 Catalogue   (180.16k)

  Indigo300 Transmitter Catalogue   (366.5k)

  DMP1 Catalogue   (517.42k)


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