ISO 7309:1985

Overview

ISO 7309:1985 specifies the ISO reference petroleum base fluid used for testing hydraulic braking systems and components in road vehicles. This international standard defines the precise chemical composition and physical characteristics of the fluid to ensure consistent and reliable evaluation of hydraulic brakes under standardized conditions. The document supports vehicle manufacturers, testing laboratories, and component producers by providing a benchmark fluid for performance measurements and quality control.

Key Topics

• Scope and Application Defines the use of the reference fluid specifically for hydraulic braking systems mounted on road vehicles to promote uniform testing procedures internationally.

• Composition of Reference Fluid The standard details a carefully formulated mixture of petroleum-based constituents, including:

  • Pentamers of hydrogenated propylene (80% ± 1.2)
  • Poly(alkyl methacrylate) (17% ± 1)
  • 1,4-di(t-butyloxy)benzene (0.5% ± 0.05)
  • Tri(isopropylphenyl) phosphate (1% ± 0.1)
  • Specific green and yellow-green colourants in trace amounts This composition ensures the reference fluid exhibits predictable and repeatable behavior when used in tests.

• Physical and Chemical Characteristics The document tabulates required properties and test methods, including:

  • Kinematic viscosity values at 40°C, 100°C, and -40°C
  • Pour point of less than -50°C
  • Flash point exceeding 105°C (Cleveland Open Cup method)
  • Initial boiling point above 240°C
  • Neutralization number below 0.2 mg KOH/g
  • Phosphorus content analyzed by X-ray fluorescence

• Test Methods Specified The standard references established ISO test methods such as ISO 3104 (viscosity), ISO 2592 (flash point), and ISO 3016 (pour point) to ensure consistency and comparability of test results.

Applications

ISO 7309:1985 is critical for:

• Vehicle Manufacturers: Ensuring hydraulic braking systems meet performance standards using a consistent test fluid.
• Brake Component Suppliers: Validating compatibility and reliability of braking components with the ISO reference fluid.
• Testing Laboratories: Providing a standardized baseline fluid to conduct repeatable and internationally comparable hydraulic brake tests.
• Quality Assurance: Supporting compliance with safety and performance regulations in automotive hydraulic braking systems.

This standard helps maintain safety and reliability in road vehicle braking by enabling uniform evaluation across borders and manufacturers.

Related Standards

• ISO 2592: Petroleum products - Determination of flash and fire points
• ISO 3016: Petroleum oils - Pour point determination
• ISO 3104: Petroleum products - Kinematic viscosity and dynamic viscosity calculation
• ISO 3405: Petroleum products - Distillation requirements
• ISO 6618: Petroleum products and lubricants - Neutralization number titration method
• Upcoming ISO 6619 standard for potentiometric method of neutralization number determination

These referenced standards complement ISO 7309 by providing the test methodologies required to characterize the petroleum base fluid accurately.

Keywords: ISO 7309, hydraulic braking systems, ISO reference petroleum base fluid, road vehicles, brake fluids, standard test fluid, brake component testing, automotive brake standards, chemical composition, physical characteristics, brake fluid viscosity, brake fluid flash point, standardized brake fluid