ASTM D156-23 PDF

Overview

ASTM D156-23 is the Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method), developed by ASTM International. This test method provides a systematic procedure for determining the color of refined oils, including undyed motor and aviation gasoline, jet propulsion fuels, naphthas, kerosene, petroleum waxes, and pharmaceutical white oils. The Saybolt color test helps users and manufacturers monitor product quality and detect potential contamination, serving as a key quality control metric in the petroleum industry.

The Saybolt Chromometer Method evaluates color on a scale from -16 (darkest) to +30 (lightest), producing results specific to this test and reported as “Saybolt Color units.” The method is designed around inch-pound units due to industry practice and equipment standards, though SI units are used for temperature and as otherwise applicable.

Key Topics

• Significance of Color Determination:

  • Color serves as a major quality characteristic in petroleum products, immediately visible to users.
  • Unusual color variations outside a known product range can indicate contamination or changes in processing.
  • Although color may suggest the degree of refinement, it should not be the sole criterion for product quality.

• Saybolt Color Scale:

  • Uses a numerical scale from -16 (dark) to +30 (light).
  • Results are measured using specific sample tube depths, matched visually against glass color standards.

• Sample Types Covered:

  • Undyed gasoline (motor and aviation)
  • Jet propulsion fuels
  • Naphthas
  • Kerosene
  • Petroleum waxes
  • Pharmaceutical white oils

• Test Method Highlights:

  • The Saybolt chromometer visually compares the sample against reference standards using controlled lighting.
  • Precision identified: repeatability is ±1 color unit, reproducibility is ±2 color units.

• Units and Apparatus:

  • Inch-pound units are standard due to apparatus design and industry adoption.
  • The chromometer consists of glass sample and standard tubes, optical system, and a designated light source.

Applications

• Manufacturing Control: During petroleum refining, regular color testing with ASTM D156-23 helps monitor the consistency and purity of products, minimizing off-spec material and providing early detection of process disruptions.

• Quality Assurance: Saybolt color values are routinely used in quality assurance protocols to ensure that products meet specification requirements before shipment or further processing.

• Contaminant Detection: Changes outside established color ranges can quickly indicate cross-contamination with other products, triggering further testing or corrective action.

• Regulatory Compliance: Many regulations and buyer requirements specify color standards for various petroleum products, making adherence to ASTM D156-23 essential for market access.

Related Standards

• ASTM D1500 - Test Method for ASTM Color of Petroleum Products (ASTM Color Scale), used for products darker than Saybolt Color -16.
• ASTM D4057 - Practice for Manual Sampling of Petroleum and Petroleum Products, referenced for correct sampling methods.
• ASTM D938 - Test Method for Congealing Point of Petroleum Waxes, relevant for sample preparation of waxes.
• ASTM D4175 - Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants.
• ASTM E308 - Practice for Computing the Colors of Objects by Using the CIE System, referenced for colorimetric calculations.

Keywords: ASTM D156, Saybolt Color, petroleum products color test, chromometer method, motor gasoline, jet fuel, naphtha, kerosine, petroleum wax, quality control, refinery product specification, ASTM standards.