ISO 7233:2021 PDF

Overview

ISO 7233:2021 specifies test methods to determine the resistance to vacuum of rubber and plastics hoses and hose assemblies. The standard defines three test methods (A, B and C), the applicable hose dimensions for each method, required apparatus, specimen preparation and conditioning, test pressures and durations, inspection criteria, and required test-report contents. Its purpose is to verify that hoses will withstand differential pressure caused by reduced internal pressure in service and to detect internal defects such as delamination.

Key topics and requirements

• Scope of methods
  • Method A: for hoses of nominal size up to and including 80. Also used to detect lining/reinforcement delamination in hard-wall hose by observing the travel of an internal ball.
  • Method B: for hoses of nominal size greater than 80; uses transparent end plates for internal visual inspection.
  • Method C: applicable to all hose dimensions; may be used as an alternative to A and B where product standards do not specify a method.
• Apparatus
  • Vacuum pump with gauge capable of reducing internal pressure to the specified value within 60 s and maintaining it for ≥10 min.
  • Method A: smooth solid ball with diameter = 0.9 × bore (rounded down to nearest mm).
  • Method B: two transparent airtight plates, one permitting visual inspection and pump attachment.
• Specimens and conditioning
  • Test pieces: minimum 1 m of hose clear of fittings (or whole hose if