Thunder Model 2500 Benchtop/Mobile "Two-Pressure" Humidity Generator

Thuner 2500 Humidity Generator
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The Model 2500 Benchtop Humidity Generator is a self contained system capable of producing atmospheres of known humidities using the fundamental, NIST proven, "two-pressure" principle.


  • Accuracy ± 0.5 %RH
  • Traceable to NIST
  • Self Contained and Mobile
  • Automated Control of User Setpoints
  • ControLog TM Automation Software
  • HumiCalc ® Humidity Conversion Software
  • Computerized Internal Transducer Calibration
  • Low Noise Air Compressor with Air Dryer
  • RS-232C Serial Interface

This system is capable of continuously supplying accurately known humidity values for instrument calibration, evaluation, and verification, as well as for environmental testing. Simply apply power and the 2500 will power-up ready to generate. Humidity setpoint values are input by the operator from the front panel keypad and are limited only by the range of the 2500 humidity generator. Relative humidities are calculated from the measurements of pressure and temperature with the formula:

%RH= fs/ fc · es/ ec · Pc/ Ps · 100

To generate a known humidity, the computer controls the pressure ratio Pc /Ps utilizing the enhancement factor ratio fs/fc and the effective degree of saturation es/ec. Humidity produced is solely dependent on the measurement of pressures and temperatures and does not rely on any other device (such as a dew point hygrometer, psychrometer, or humidity sensor) for the measurement of water vapor content. Precision humidity generation is determined by the accuracy of the pressure measurements and on the accuracy and uniformity of temperature throughout the generating system.