Overview
ISO 4397:2011 - Fluid power connectors and associated components - specifies the nominal outside diameters of rigid or semi‑rigid tubes and the nominal hose sizes to be used with hydraulic and pneumatic fluid power connectors and associated components. It defines the standard nominal sizes (irrespective of tube material) and provides a list of nominal hose sizes (rubber or plastic) to ensure compatibility between tubes, hoses and connectors in fluid power systems.
Key topics and requirements
- Scope
- Covers nominal outside diameters for rigid or semi‑rigid tubes used in fluid power.
- Lists nominal sizes for hoses made of rubber or plastic used in fluid power.
- Selection rule
- Nominal outside diameters for tubes shall be selected from the values given in Table 1.
- Nominal hose sizes shall be selected from the values given in Table 2.
- Tube nominal outside diameters (mm)
3, 4, 5, 6, 8, 10, 12, 15, 16, 18, 20, 22, 25, 28, 30, 32, 35, 38, 42, 50, 60, 75, 90, 100, 115, 140
- Nominal hose sizes (mm)
3.2, 4, 5, 6.3, 8, 10, 12.5, 16, 19, 25, 31.5, 38, 51, 63, 76, 90, 100, 125, 150
- References for actual dimensions and tolerances
- For actual outside diameters and tolerances of steel tubes: see ISO 3304 and ISO 3305.
- For hose inside diameters and tolerances: see ISO 1307.
- Terminology
- Terms and definitions follow ISO 5598 (Fluid power systems and components - Vocabulary).
Applications and users
ISO 4397:2011 is practical for:
- Engineers and designers specifying hydraulic and pneumatic systems who need standardized tube and hose nominal sizes for connector compatibility.
- Manufacturers of fluid power connectors, fittings, tubes and hoses to harmonize product dimensions.
- Procurement, quality and testing teams for selection, documentation and verification of connector/interface compatibility.
- Catalogues and technical datasheets where the identification statement is required:
“Nominal outside diameters of tubes and/or nominal hose sizes are in accordance with ISO 4397:2011.”
Using ISO 4397 helps reduce mismatches between hoses, tubes and connectors, simplify inventory management, and support international interoperability in fluid power systems.
Related standards
- ISO 5598 - Fluid power systems and components: Vocabulary
- ISO 1307 - Rubber and plastics hoses: hose sizes and inside diameter tolerances
- ISO 3304 / ISO 3305 - Plain end steel tubes: technical delivery conditions
Keywords: ISO 4397:2011, fluid power connectors, nominal outside diameters, tube sizes, hose sizes, hydraulic, pneumatic, tubes and hoses, connector compatibility.
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