ASTM D7058 Standard Test Method for Determination of the Red Dye Concentration and Estimation of Saybolt Color of Aviation Turbine Fuels and Kerosine Using a Portable Visible Spectrophotometer
7. Apparatus
7.1 Filter Spectrophotometer, is equipped with specimen chamber, visible wavelength source, three 10 +/- 2 nm bandpass wavelength discriminating filters having center wavelengths at approximately 420 +/- 5 nm, 520 +/- 5 nm, and 650 +/- 5 nm. The bandpass filters are used in conjunction with the visible wavelength source to produce light in the blue, green, and red regions of the electromagnetic spectrum. A detector converts the transmitted light to an electronic signal that is processed by an A-D converter and a microprocessor.
7.2 Sample Cell, constructed of polymethacrylate or clear optical glass having a path length of approximately 12 cm. If more than one cell is used for calibration, validation, and sample measurement, the path length of the cells must be matched to +/- 0.005 cm.
