Moisture in Oil, Fuel Transmitter

Vaisala HUMICAP® MMT310 Series provides continuous online measurement of moisture and temperature in transformer, lubrication and hydraulic oils.

The compact transmitter measures water activity (a_w) or relative saturation (%RS), showing how close the oil is to forming free water. Optional ppm calculation is available for mineral transformer oil and configured oil types.

• Models MMT317 and MMT318
• Water activity range: 0 to 1 a_w
• Temperature range: -40 to +180°C
• Two configurable analogue outputs and RS-232C
• Up to 40 bar with MMT318 and ball-valve installation
• IP66 compact transmitter enclosure
• Traceable calibration certificates included

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

The Vaisala MM70 was a portable meter for spot-checking water activity and temperature in transformer, lubrication and hydraulic oils.

• Discontinued product; not recommended for new purchases
• Legacy MI70 handheld indicator with MMP78 moisture-in-oil probe
• Water-activity measurement from 0 to 1 a_w
• Temperature measurement from −40 to +100 °C
• Direct insertion through a ball valve without draining the process
• Numerical display, trend graph and portable data logging

The Vaisala Indigo500 Series provides flagship industrial measurement integration: choose Indigo510 for a simplified single-probe system or Indigo520 for full dual-probe capability.

• Indigo510: one probe and two isolated analog outputs
• Indigo520: two probes, four isolated outputs and two relays
• Ethernet web interface and Modbus TCP communication
• Rugged IP66 and NEMA 4 metal enclosure

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 MMP8 provides continuous online measurement of dissolved moisture and temperature in transformer oil, lubrication oil, hydraulic fluid and other liquid hydrocarbons.

• Measures water activity from 0 to 1 a_w, relative saturation, temperature and ppm_w
• Dry-end accuracy up to ±0.01 a_w or ±1%RS
• Temperature measurement from −40 to +180 °C
• Available in standard 262 mm and long 448 mm probe versions
• Adjustable insertion depth with ISO 1/2 or NPT 1/2 process fittings
• Standalone Modbus RTU or connection to Vaisala Indigo transmitters