Total radiation pyrometry

While disappearing filament pyrometers are convenient and accurate, they require human interaction and hence are not well suited for use in feedback control systems. In a total radiation pyrometer, a lens system focuses incoming radiation onto 

Fitting blackbody and detector temperature data to this function should yield a straight-line fit, allowing determination of n and In C as slope and intercept, respectively. 

Usage of this device for non-blackbody sources is not practical. Greybody conditions would have to be valid over the entire spectrum incident on the detector in order to legitimately apply an emittance correction. 

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A significant concern in the use of total radiation pyrometry is that it must be calibrated at the distance it will be from the source because of the influence of the atmosphere. Normal atmosphere contains a small fraction of carbon dioxide and water vapor (the latter dependent on the relative humidity, which varies with the day). When combustion is used for furnace heating (e.g. CH4+2O2 = 2H2O+CO2), water vapor and carbon dioxide are the predominant, atmospheric constituents. As... 

Equation (5) states that the total radiation of all wave lengths emitted by a black body is proportional to These two laws which form the basis of optical and radiation pyrometry respectively are in agreement with the temperature scale defined by the gas thermometer up to 1,550°C., the upper limit at which a gas thermometer has been used satisfactorily. Above this range to 2,500°C. the scales defined by these two laws have been found, experimentally, to be in mutual agreement, and it is believed that they correctly represent the thermodynamic scale for all temperatures. 

The definite integral can be evaluated to give a purely numerical quantity, so that the total radiation density is seen to be proportional to the fourth power of the absolute temperature. This is Stefan s law, also a well-known result of experiment and the basis of high-tempera-ture pyrometry. 

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