Ruber hoses and hose assemblies - Rubber-covered spiral wire reinforced hydraulic type - Specification; German version EN 856:2015
1Key Takeaways
This European Standard specifies the technical requirements for four types of rubber covered spiral wire reinforced hydraulic hoses and hose assemblies with nominal inside diameters from 6 to 51: Types 4SP, 4SH, R12 and R13. They are suitable for use with: ——hydraulic fluids conforming to ISO 6743-4, except HFD R, HFD…
2Expert Interpretation
This in-depth analysis of the DIN EN 856:2020-08 hydraulic rubber hose standard covers the technical requirements, dimensional tolerances, pressure ratings, and test methods for four wire spiral reinforcement types: 4SP, 4SH, R12, and R13, providing professional guidance for hose selection in hydraulic systems.
Analysis of the Core Content of the EN 856 Standard
DIN EN 856:2020-08, a key technical specification for rubber hoses used in hydraulic systems, replaces the 2016 edition and sets comprehensive technical requirements for four types of steel spiral-reinforced hydraulic hoses (4SP, 4SH, R12, and R13). This standard applies to hoses and hose assemblies with a nominal inner diameter of 6 to 51 mm and covers an operating temperature range of -40°C to +120°C.
Comparison of hose types and technical characteristics
| Type | Pressure level | Maximum operating temperature | Minimum bending radius example | Impulse test requirements |
|---|---|---|---|---|
| 4SP | Medium pressure | 100°C | DN6: 150mm | 400,000 times (133% working pressure) |
| 4SH | Ultra-high pressure | 100°C | DN6: 130mm | 400,000 times (133% working pressure) |
| R12 | Medium pressure | 120°C | DN12: 240mm | 500,000 times (133% working pressure) |
| R13 | High pressure | 120°C | DN12: 240mm | 500,000 times (120% working pressure) |
Detailed Explanation of Dimensional Tolerance Requirements
The standard strictly stipulates the dimensional tolerance of hoses. The inner diameter tolerance varies according to the nominal diameter:
- Nominal diameter ≤6mm: inner diameter tolerance ±0.4mm
- 6mm＜nominal diameter ≤19mm: inner diameter tolerance ±0.6mm
- Nominal diameter＞19mm: inner diameter tolerance ±0.8mm
The concentricity requirements are equally strict. The maximum deviation between the inner diameter and the reinforcement layer diameter does not exceed 0.5-0.9mm to ensure uniform stress on the hose during use.
Technical Requirements for Pressure Performance
The standard specifies detailed pressure test requirements, including proof pressure, burst pressure and maximum working pressure:
| Nominal diameter (mm) | Type | Maximum working pressure (bar) | Proof pressure (bar) | Burst pressure (bar) |
|---|---|---|---|---|
| 6 | 4SP | 450 | 900 | 1800 |
| 51 | 4SH | 250 | 500 | 1000 |
| 38 | R13 | 345 | 690 | 1380 |
Material Structure and Performance Requirements
The hose construction consists of an oil- and water-resistant synthetic rubber inner liner, a spiral steel wire layer with alternating winding directions, and an oil- and weather-resistant synthetic rubber outer layer. Each spiral steel wire layer is separated by a synthetic rubber insulation layer to ensure good interlayer adhesion.
Bond strength requirement: 4SP and 4SH types must be no less than 2.5 kN/m, and R12 and R13 types must be no less than 1.4 kN/m. Abrasion testing requires a mass loss of no more than 1 g (2000 cycles, 50 N vertical force).
Fluid Compatibility Test Specification
The standard specifies in detail the compatibility requirements between hose materials and various hydraulic fluids:
- Oil resistance test: Use No. 3 oil specified in ISO 1817, immersion for 168 hours at 100°C
- Water-based fluid test: 1:1 mixture of ethylene glycol and distilled water, 168 hours at 70°C
- Water resistance test: Immersion in distilled water at 70°C for 168 hours
The volume expansion rate limit varies according to the type and location of the hose. The maximum expansion rate of the lining layer is 25-60%, and the maximum expansion rate of the outer layer is 100-125%.
Test Methods and Acceptance Criteria
The standard appendix provides detailed test methods, including:
- Hydrostatic Pressure Test: Performed in accordance with EN ISO 1402
- Impulse Test: Performed in accordance with EN ISO 6803, test temperature 100-120°C
- Abrasion Test: Using the dedicated equipment and procedures specified in Appendix A
- Low-Temperature Flexibility Test: Performed in accordance with EN ISO 10619-2 Method B at -40°C
Marking and Labeling Requirements
Hoses must be marked with the following information at intervals of no more than 500mm: manufacturer's identification, standard number EN 856, type, nominal diameter, year and quarter of production. Hose assemblies must also be marked with the maximum working pressure and assembly date.
Example marking: XXX/EN 856/4SP/16/1Q15, where 1Q15 indicates production in the first quarter of 2015.
Implementation recommendations and precautions
Based on the requirements of the standard, the following implementation recommendations are proposed:
- Selection guidance: Select the appropriate hose type based on the working pressure, temperature and media characteristics
- Installation specifications: Ensure that the bending radius is not less than the minimum value specified in the standard
- Regular inspection: Establish a regular inspection system based on the requirements of the standard
- Scrap standards: Establish hose replacement standards based on the degree of wear and aging
Special note: This standard does not apply to castor oil-based and ester-based fluids, nor does it include requirements for hydraulic hoses used in underground mining.