ISO 7375-2:1998

Overview

ISO 7375-2:1998 specifies the performance requirements for coiled tube assemblies used in air brake connections between towing and towed road vehicles. This international standard, developed by ISO Technical Committee ISO/TC 22 and Subcommittee SC 2 for brake systems and equipment, focuses on thermoplastic tubing assemblies fitted with suitable end fittings. Designed for vehicle combinations equipped with air brake systems, the standard ensures reliability, safety, and durability of pneumatic connections essential for effective braking performance.

The standard applies to coiled tube assemblies manufactured from virgin thermoplastic materials, capable of withstanding working pressures up to either 1,000 kPa or 1,250 kPa, operating safely within temperatures ranging from -40 °C to +100 °C. This ensures compatibility with rigorous vehicle operating conditions.

Key Topics

• Material Requirements
  Tubing must be extruded from 100% virgin thermoplastic with specific reinforcement suitability to guarantee strength and longevity.

• Design and Installation
  End fittings must be approved by vehicle manufacturers, and installation must comply with ISO 1728 to prevent damage during assembly and use.

• Testing Procedures
  Comprehensive testing validates assembly performance, including:

  • Extension Test: Coiled tubes must extend to working length within a specified time frame with minimal force.
  • Low Temperature Extension Test: Ensures flexibility and extension capability at -40 °C.
  • Coil Recovery Test: Assesses ability to return to original coil shape after extension at both ambient and elevated temperatures.
  • Leak Test: Validates airtight integrity with fittings installed.
  • Fitting Pull-Off Test: Checks firm attachment of fittings after thermal cycling between extreme temperatures.
  • Articulation Test: Subjects assemblies to repeated bending cycles to simulate operational movement without kinking or fitting displacement.
  • Kink Test: Ensures tubes resist kinking under applied lateral forces during use.

• Marking Requirements
  Coiled tube assemblies must be permanently marked with standard identification details including manufacturer code, production date, material type, and ISO 7375 compliance, supporting traceability and quality assurance.

Applications

ISO 7375-2’s coiled tube assemblies are fundamental components in air brake systems connecting tractor units and trailers or other towed vehicle types, commonly used in:

• Trucks and trailers
• Buses and coaches
• Commercial freight vehicles
• Vehicle combinations requiring robust pneumatic brake linkages

These assemblies ensure safe air supply transmission for braking systems, enhancing road safety, vehicle performance, and compliance with international vehicle regulations.

Related Standards

ISO 7375-2 is part of a broader family addressing coiled tube assemblies and pneumatic braking connections, including:

• ISO 7375-1: Dimensions of coiled pipe assemblies for air brake connections
• ISO 1728: Pneumatic braking connection interchangeability between motor vehicles and towed vehicles
• ISO 7628-1 and -2: Specifications covering thermoplastic tubing for air braking systems, including dimensions, installation, and testing methods
• ISO 1043 series: Terminology and symbols for plastics materials used in tubing manufacture

Implementing ISO 7375-2 together with these related standards facilitates harmonized engineering, product testing, and quality management of air brake system tubes, ensuring optimal safety and compatibility globally.

By adhering to ISO 7375-2:1998, manufacturers, vehicle assemblers, and maintenance professionals can ensure that coiled tube assemblies for air brake connections meet critical performance standards essential for reliable, safe, and durable road vehicle operations.