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  • Operating environment
    • DMT345: temperatures up to 180°C (356 °F)
    • DMT346: temperatures up to 350 °C (662 °F)
  • Range
    • DMT345: -40 to 100 °C (-40 to 212 °F)
    • DMT346: -25 to 100 °C (-13 to 212 °F)
  • Accuracy: ±2 °C (±3.6 °F) for both models
  • Unique auto-calibration
  • Vaisala DRYCAP® Sensor provides accurate, reliable measurement with excellent long-term stability and fast response
  • Withstands condensation
  • Optional local display with keypad, mains power supply module and alarm relays
  • User-programmable, versatile and easy to use
  • Integrated data logging, with over four years of measured history
  • LAN and WLAN communication options

The Vaisala DMT345 and DMT346 Dewpoint Transmitters are designed for humidity measurement in industrial drying applications with particularly high temperatures.

Both transmitters incorporate the Vaisala DRYCAP® sensor, which is accurate, reliable, and stable. The sensor withstands condensation and is immune to particulate contamination, oil vapor and most chemicals. The DRYCAP® sensor stands out for its swift response time and rapid recovery after getting wet.

The DMT345 and DMT346 are constructed for direct measurement in hot processes. Therefore, there is no need for sampling systems and trace heating. As a result, high accuracy and constancy are maintained.

The accuracy and stability of the DMT345 and the DMT346 are due to the unique auto-calibration function, patented by Vaisala. This auto-calibration makes the transmitter perform a calibration and adjustment by itself while the measured process is running. If the measurement accuracy is not confirmed, corrections are made automatically. The procedure is so quick and corrections are so minor that it will go unnoticed. This ensures low maintenance and high performance. In normal conditions, it is recommended to have a traceable calibration performed once a year.

The DMT345 is designed for temperatures up to 140 °C. It can, however, operate safely in temperatures up to 180 °C. The stainless steel probe is especially designed for high temperatures and has an optional installation flange that allows an adjustable installation depth and, therefore, precise positioning. When process temperatures range between 140 to 350 °C, the DMT346 provides the best measurement performance. The DMT346 comes with a cooling set as a standard feature. The cooling effect may be regulated by adding or removing the cooling fins. The cooling system operates without moving parts, additional power or cooling utilities, thereby eliminating the risk of sensor damage due to a mechanical cooling failure. Additionally, sensor warming minimizes the risk of condensing on the sensor. In low humidity the combination of auto-calibration and DRYCAP® ensures accurate measurement.

The DMT345 and DMT346 transmitters are available with a large numerical and graphical display allowing the user to clearly monitor operational data, measurement trends and up to one-year of measurement history. The optional data logger with real-time clock makes it possible to generate more than four years of the measured history and zoom in on any desired time or time frame. The recorded data can be transferred to a PC with Microsoft Windows® software.

The Vaisala DMT345 and DMT346 can be connected to a network with an optional (W)LAN interface, which enables a wireless) Ethernet connection. For serial interface, the USB connection, RS232 and RS485 can be used. The transmitter can have up to three analog outputs. The transmitters are also capable of applying the MODBUS communication protocol and, together with an appropriate connection option, provide either MODBUS RTU (RS485) or MODBUS TCP/IP (Ethernet) communication. Units are delivered installation-ready.