Vaisala MMT330 Moisture in Oil Transmitter Series – Discontinued

Vaisala MMT330 Moisture in Oil Transmitter Series – Discontinued

The Vaisala MMT330 Series provided continuous measurement of moisture and temperature in transformer oil, lubrication oil, hydraulic fluid and other liquid hydrocarbons.

  • Discontinued series; not recommended for new installations
  • Legacy MMT332, MMT337 and MMT338 probe configurations
  • Measures water activity, relative saturation, temperature and calculated ppm
  • Graphical display, data logging and versatile analogue or digital outputs
  • Used for oil-condition monitoring, dryer control and free-water risk detection
  • Use Vaisala MMP8 with an Indigo transmitter for new installations

Legacy Online Moisture Measurement for Oil

The Vaisala MMT330 was designed for continuous measurement of dissolved moisture in oil. It helped operators detect water ingress, monitor oil dryers and purifiers, and assess how close the oil was to the point at which free water could form.

The series combined a fixed probe with an IP66 metal transmitter housing. Depending on the selected model, the probe could be fitted to a high-pressure process, installed through a threaded connection in a restricted space, or inserted into a pressurised pipeline.

Discontinued series: For new projects, Vaisala directs MMT330 users to the MMP8 Moisture in Oil Probe. Pair it with a compatible Indigo transmitter when a display, analogue outputs, relays, Ethernet or additional system connectivity is required.

MMT330 Model Guide

Legacy modelProbe arrangementTypical installationReplacement direction
MMT332 Small flanged probe High-pressure processes MMP8 with the suitable process fitting and pressure review
MMT337 Small pressure-tight probe with threaded connection Restricted spaces and fixed process connections MMP8 after checking available space, thread and insertion depth
MMT338 Adjustable-length probe Pressurised pipelines, including installations requiring controlled insertion depth MMP8 with the appropriate ISO or NPT fitting and, where required, ball-valve installation kit

Legacy MMT330 Measurement Specifications

SpecificationMMT330 Series
Primary measurement Water activity from 0 to 1 aw
Water-activity accuracy ±0.02 aw from 0 to 0.9 aw; ±0.03 aw from 0.9 to 1.0 aw
Moisture sensor Vaisala HUMICAP®
Calculated quantities Relative saturation and water concentration in ppm for configured oils
Temperature Measured by the probe; applicable range depended on the selected model and installation
Display Optional graphical display with trend and measurement history views

Legacy Outputs and Transmitter Construction

FeatureMMT330 provision
Analogue outputs Two standard outputs with an optional third output; current and voltage selections were available
Digital communication RS-232 standard; RS-485 with Modbus RTU available as an option
Relays Optional potential-free relay outputs
Power supply 10 to 35 VDC or 24 VAC, with additional power-supply options depending on configuration
Housing Metal transmitter enclosure, IP66; display versions were IP65
Mounting Wall, DIN rail, pole or pipeline mounting accessories were available
Probe cable Fixed probe cable; lengths depended on the ordered configuration

MMT330 and MMP8 with Indigo Comparison

Selection pointMMT330 SeriesMMP8 with Indigo
Product architecture Probe permanently connected to the transmitter Interchangeable smart probe connected to a selected Indigo transmitter
Moisture accuracy at +20 °C 2 %RS specified accuracy 1 %RS specified accuracy under stated conditions
Temperature accuracy at +20 °C ±0.2 °C ±0.2 °C
Probe output Signal processing tied to the transmitter Standalone Modbus RTU from the MMP8, or expanded outputs through Indigo
Probe replacement Probe and transmitter formed one measurement assembly MMP8 can be exchanged independently, subject to configuration and system checks
PC software Legacy service interface and terminal software Vaisala Insight for configuration, diagnostics and calibration work
Display and local interface Optional keypad display Selected through the Indigo transmitter or Indigo80 handheld
System connectivity Analogue outputs and optional Modbus RTU Modbus RTU from the probe; analogue, relay, Modbus TCP and other options depend on the Indigo model

Choose the MMP8 and Indigo Arrangement

RequirementRecommended starting pointWhy it fits
Direct digital integration MMP8 as a standalone Modbus RTU probe Suitable where the host system can power and communicate directly with the probe
Compact local transmitter MMP8 with Indigo200 Adds a local display and practical analogue, relay or Modbus connectivity according to model
Rugged single-probe installation MMP8 with Indigo300 Provides an industrial metal enclosure, display and configurable analogue outputs
Closest flagship transmitter migration MMP8 with Indigo510 or Indigo520 Provides robust enclosure, graphical interface and expanded plant-system connectivity
Portable diagnostics and spot checks Indigo80 with MMP8 Allows portable display, logging, diagnostics and field configuration with the same probe platform

Typical Moisture-in-Oil Applications

ApplicationMeasurement purposeSelection consideration
Power transformers Track dissolved moisture and changes in insulation-oil condition Confirm the required ppm calculation and representative oil-circulation point
Lubrication systems Detect water ingress before free water threatens bearings and oil performance Review normal oil temperature, pressure, flow and contamination exposure
Hydraulic systems Monitor moisture loading that can affect fluid and component life Select a stable pressurised measurement point with safe service access
Oil dryers and purifiers Monitor drying performance and control the treatment process Compare inlet and outlet conditions under consistent temperature and flow
Marine and rotating equipment Identify ingress and trend oil condition during operation Consider vibration, access, installation pressure and probe-removal procedure

Water Activity, Relative Saturation and ppm

Water activity, aw, indicates how close oil is to moisture saturation at the measured temperature. A value approaching 1 aw means the oil is approaching the condition in which free water may form. Relative saturation expresses the same relationship on a 0 to 100% scale.

A ppm value estimates the mass concentration of water in the oil. This conversion depends on the solubility behaviour of the specific oil, which can change with oil type, age and additives. Where ppm is required, the correct oil-specific coefficients and calculation method should be reviewed during migration.

Planning an MMT330 Replacement

  1. Identify whether the installed unit is an MMT332, MMT337 or MMT338.
  2. Record the complete order code, probe cable length, process fitting and mounting accessories.
  3. Confirm the oil type, normal temperature, operating pressure, flow and required insertion depth.
  4. List every required output, relay, communication protocol, supply voltage and local-display function.
  5. Check whether existing ppm conversion coefficients must be transferred or reviewed.
  6. Select the standard or long MMP8 and the correct ISO or NPT process fitting.
  7. Choose the Indigo transmitter from the required enclosure, display, outputs and communication interfaces.
  8. Verify the replacement at the same stable process condition before retiring the MMT330.

Vaisala MMT330 Replacement Support in Malaysia

Seacom Process Instruments supports users of the discontinued Vaisala MMT330 Moisture in Oil Transmitter Series in Malaysia and supplies the MMP8 and Indigo platform for new continuous and portable moisture-in-oil applications.

Our team can assist with legacy model identification, probe-length and process-fitting selection, ball-valve arrangements, transmitter outputs, system integration, oil-specific ppm configuration, commissioning and calibration planning.

Replacing an MMT330? Send Seacom a photograph of the transmitter label and probe installation, together with the oil type, temperature, pressure, fitting, insertion depth, supply voltage and required outputs. We will help check the suitable MMP8 and Indigo configuration.

Download

  MMP8 Catalogue   (190.61k)

  Indigo200 Catalogue   (204.62k)

  Indigo 500 Catalogue   (581.96k)

  MMT330 Series Catalogue   (570.34k)

  MMT330 series Order Form   (122.8k)

  Indigo300 Transmitter Catalogue   (366.5k)


Specific References

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