Abstract: In a chromatographic analysis, errors in the chromatographic analysis caused by barometric pressure variations are corrected by dividing the actual measured analysis (C.sub.m) by a correction factor which is calculated based on the actual atmospheric pressure at the time the measurement is made (P.sub.a), the atmospheric pressure at which the chromatographic analyzer system was calibrated, and the slope of a plot of C.sub.m /C.sub.a as a function of P.sub.a /P.sub.c where C.sub.a is the magnitude that C.sub.m would have if errors were not introduced by changes in barometric pressure.

Abstract: A continually repeated chemical analysis of a process stream sample is effected by interposing the sample in a flow of titrant, flow of which is interrupted only to permit the interposition of the sample in the line of flow. A holding zone or chamber, e.g. a chromatographic column receives and holds titrant until the interposed sample in the column is titrated. Reaction product eluted from the column is detected.

Abstract: In a chromatographic analysis system a bypass conduit operating in parallel with a chromatographic separation column diverts a portion of the sample fluid directly to the chromatographic detector prior to elution through the chromatographic separation column of the remaining portion of the sample material. Comparison of the detector response to the bypassed portion of the sample with the detector response to selected constituents or groups of constituents exiting the chromatographic separation column is used to normalize the analysis response to one or more constituents or groups of constituents eluted through the chromatographic separation column.

Abstract: A method and apparatus is disclosed for providing a very reproducible chromatographic analyzer output by reducing variations in the chromatographic analyzer output due to changes in barometric pressure. An absolute back pressure regulator is utilized to provide a reference pressure for the chromatographic analyzer system. The reference pressure is not affected by changes in barometric pressure and thus the chromatographic output is not affected by changes in barometric pressure.Method and apparatus is also disclosed for reducing noise in a chromatographic analyzer system caused by pressure variations due to the switching of the chromatographic analyzer sample valve. A pneumatic accumulator is utilized to smooth small pressure surges resulting from actuation of the chromatographic analyzer sample valve and thus provides a smoother and more reproducible chromatographic analyzer output signal.

Abstract: A method and apparatus is disclosed for correcting errors in a chromatographic analysis caused by changes in ambient atmospheric pressure. The output signal from a chromatograph is summed with the output signal from a pressure transducer. The output signal from the pressure transducer varies with changes in the atmospheric pressure from a reference pressure and is calibrated in such a manner as to provide a corrected chromatographic analyzer output signal when it is summed with the output signal from the chromatograph. In this manner pressure compensation is provided where normalization of the chromatographic analyzer output signal is not possible or is undesirable.

Abstract: Analysis of the reflectance characteristics of a surface such as a sample of knitted fabric utilizes one or more photosensitive detector means to scan the surface and to automatically produce at least one surface quality signal in response to the reflective characteristics of the surface. In preferred embodiments of the invention a modulated light source is used to illuminate the surface in order to minimize the effect of ambient lighting conditions, and a plurality of detector means are used to obtain a more accurate representation of the quality of the surface being scanned.