Pressure and gas-dependence of humidity sensors and analyzers

Andrea Peruzzi, VSL (NL)

In the framework of the European Metrology Research Programme  (EMPR) project Biogases, the pressure and gas-dependence of humidity sensors and analyzers was investigated using the VSL flow-mixing humidity standard. Nitrogen, pure methane and synthetic biogas mixtures (CH4, CO2 and N2) were used as carrier gases at pressures ranging from atmospheric to 6 MPa to investigate the performances of different devices: chilled mirror hygrometer, Fabry-Perot interferometer, quartz crystal microbalance, tunable diode laser and impedance sensor. The investigated dew/frost point temperature range was -20 ⁰C to +15 ⁰C.
The accuracy of the flow-mixing humidity standard was found to be critically dependent on the knowledge of the enhancement factor, which for the energy gases is still not well known. Parallel measurements with calibrated chilled mirror hygrometers provided preliminary information on the energy gases enhancement factors.


Pen Profile

I graduated in Physics at the University of Florence in 1995 and received my PhD in Materials Science and Engineering from the same university in 1998. Since June 2000 I work for the VSL, the Dutch Metrology Institute, now as principal scientist for temperature and humidity.

Since 2005, I am involved in the development of a primary high-pressure non-air dew-point generator based on first thermodynamic principles, to serve the traceability needs of the natural gas industry.

In the past three years, the same primary dew-point generator has been employed in the framework of a joint EC/EURAMET project on biogas to investigate how the performances of the commercial devices, usually used to monitor the water content of natural gas, are affected when used on biogas-like synthetic mixtures.

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