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Chapter 17 Respiratory Function
Published in B H Brown, R H Smallwood, D C Barber, P V Lawford, D R Hose, Medical Physics and Biomedical Engineering, 2017
The helium analyser is usually based upon a measurement of the thermal conductivity of the gas. The gas is passed through a cell and the transfer of heat from a heater to a temperature sensor is measured. This type of measurement is not specific to a particular gas and so corrections have to be applied for the amount of other gases, such as oxygen and nitrogen, which are present.
Experimental Investigation of Natural Circulation During Air-Ingress Scenario in a Very High Temperature Reactor
Published in Nuclear Science and Engineering, 2019
Apoorva V. Rudra, Dinesh V. Kalaga, Masahiro Kawaji
The volumetric concentrations of helium and nitrogen were recorded with the help of helium analyzers (Divesoft, M12) which were connected to the upper and lower plena through gas sampling ports (6) and (11) shown in Fig. 2a. A small volume of gas was sampled from each port for 30 s at certain time intervals and passed through a needle valve to reduce the pressure before flowing through the helium analyzer and being discharged to the atmosphere. The volumetric helium concentration in the gas sample was determined with the help of an electrochemical sensor in the helium analyzer which gave an output voltage proportional to the helium concentration in the gas mixture. For a greater accuracy of the measurement, a two-point calibration was performed with pure helium and nitrogen. The helium analyzer measured the speed of sound in the gas mixture which depends on the gas temperature and concentrations of helium and nitrogen, but little on the gas pressure. The speed of sound can be described in the mixture by a nonlinear function of the helium and nitrogen concentrations as well as the temperature of the gas mixture.