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373 Dew Point Mirror

The 373 has been measuring humidity for almost 20 years. Incremental development based on operational experience and customer feedback means that the 373 continues to exceed the expectations of hundreds of users in some of the most challenging humidity applications and mission critical industries.

Despite its high performance and specification, the 373 is easy to use and simple to maintain. The touch panel user interface is simple and intuitive to use and enables even inexperienced users to perform measurements successfully. Even early instruments remain serviceable thanks to the use of industry standard components and careful control of software build records.

A unique feature of the 373 is its dual mirror PRT configuration.  In standards laboratories, this means that the user can use an external resistance bridge to measure the mirror temperature independent of the 373 electronics so that measurement uncertainty can be reduced, and long-term stability maintained in the event of changes to the 373 measurement electronics.

The latest 373 developments include improved materials of construction to further reduce sorption effects, higher pressure capability based on new measuring head designs, data acquisition software with automated humidity generator control, and multichannel thermometer data integration.


  • Wide measuring range -95 to +95 ̊C frost/dew point
  • Dual mirror temperature sensors
  • Removable mirror module for calibration in liquid
  • Heated measuring heads and sampling systems
  • High pressures up to 20000 kPa
  • Temperature controlled sampling system
  • Fast response
  • Touch screen full color LCD user interface

Key Specifications

  • Frost/dew point range: -95 to +95 ̊C
  • Sample gas inlet pressure range: 50 to 20000 kPa
  • Temperature measurement: -50 to +100 ̊C
  • Temperature measurement with T12: -200 to +250  ̊C

Typical Applications

  • Calibration transfer standard
  • Meteorology reference
  • Fundamental research projects
  • Trace humidity measurement
  • Critical process monitoring
  • Fuel cell research