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Online Monitoring of
ASTM Color (0-7) 

Online Monitoring of ASTM Color (0-7) With a ClearView db Photometer

The purpose of this application note is to determine ASTM (D1500) color with our cost-effective GUIDED WAVE™ ClearView® db Fiber Optic Photometer.

ASTM color (reference ASTM D1500, ASTM D1524) describes the color measurement method for fuels including lubricating oils, heating oils, diesel fuels, and petroleum waxes. The color scale ranges from 0.5 to 8. The lowest value of 0.5 being a light yellow, 2 being yellow, 5 being orange, and 8 being a deep red. ASTM color is an important product quality measurement for many refinery and petrochemical processes.

Summary of ASTM Measurement Results

The ClearView db Dual Beam Fiber Optic Photometer is an excellent choice for on-line, real-time ASTM color measurement from 0 to 7. It can be configured with 4-20 mA analog outputs (6 outputs max on a single channel system, and 4 outputs per channel on a dual channel system) and corresponding contact closure outputs to alert error states. The ClearView db is also capable of Modbus communication via Ethernet.

The resulting calibration is shown in figure 1. The linear calibration gives an R2 value of 0.994 and a standard error of ±0.2 ASTM units. (An R2 value of 1 indicates a perfect correlation between the model and reference method). The ClearView db Dual Beam Fiber Optic Photometer has long term photometric drift of <500 μAU rms, which provides for excellent long term measurement stability.

Figure 1 In-situ process ASTM measurement compared to QC LAB validation

Certified standards for ASTM color (<0.5 to 7) were used to calibrate a ClearView db Dual Beam Fiber Optic Photometer. It provides the ability to measure two separate sample locations on-line, in real time. The ASTM color configured ClearView db has two analytical wavelengths and one reference wavelength. The photometer is connected via fiber optics to a sample cell (flow cell or inline probe) with a 5 mm pathlength. Measurements of five certified standards were collected.

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