engleski

A New Two Temperature Humidity Generator as a Primary Standard For Measuring Humidity in Croatia

This paper describes the principle and design of two temperature humidity generator being developed at the Laboratory for Process Measurement. It is designed to eventually operate in dew point range from -15°C to 60°C and in test chamber range to 90°C, thus catering to most of the present demand for calibration in Croatia. The flow through saturator, test chamber and test chamber bypass loop is monitored and set to the desired levels with flow meters and valves. It can be adjusted from fully recirculating flow to fully open circuit flow. Gas saturation degree is determined by measuring the temperature differences between saturator gas outlet and liquid at the saturator inlet. Temperature controllers, thermometers and resistance bridge are connected to computer via digital interfaces and integrated into monitoring and control system on the custom designed, Labview based platform. The initial results of generator evaluation are presented for recirculating mode and for part of the operating range. They include saturator and test chamber responses to stepwise parameter changes and uncertainty estimates in terms of dew point and relative humidity.

humidity standard; calibration; uncertainty

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