Measuring and testing – Instrument proving or calibrating – Volume of flow – speed of flow – volume rate of flow – or mass...
Patent
1989-05-09
1991-04-23
Noland, Tom
Measuring and testing
Instrument proving or calibrating
Volume of flow, speed of flow, volume rate of flow, or mass...
73 2322, 356307, 36457102, G01D 1800, G01N 2173
Patent
active
050090992
ABSTRACT:
A method of correcting for background changes in a plasma emission detector comprising a photodetector array is disclosed. In the photodetector array a plurality of sensors are used to detect the emission lines from a discrete number of selected elements including carbon. It is shown that, to the first order, there is a correlation between the response at detectors other than the carbon detector with the response at a carbon detector. The exact extent of this correlation is highly dependent on the amount of nitrogen present in the carrier gas used in the system. A calibration curve can be generated which allows compensation at a frequency of interest as a function of the magnitude of the carbon signal. This curve will depend on the level of nitrogen in the carrier gas and can be empirically determined each time a new bottle of gas is connected to the system. In a preferred embodiment, the calibration curve is not referred to unitl the carbon response reaches a preselected threshold value corresponding to the point on the calibration curve where there is a measurable spurious reading.
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Bolton Barbara A.
Wells Gregory J.
Cole Stanley Z.
Noland Tom
Schnapf David
Varian Associates Inc.
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