Plastics hoses and hose assemblies - Textile-reinforced types for hydraulic applications - Specification (ISO 3949:2020, Corrected version 2020-12); German version EN ISO 3949:2020
1Key Takeaways
This document specifies requirements for three types of textile-reinforced thermoplastic hoses and hose assemblies with nominal diameters from 3.2 to 25 mm. Depending on the electrical conductivity requirements, each type is divided into two classes. They are suitable for use with the oil-based hydraulic fluids HH, HL,…
2Expert Interpretation
An in-depth analysis of DIN EN ISO 3949:2021, the technical specification for fabric-reinforced plastic hoses for hydraulic applications, covers core indicators such as dimensional requirements, physical properties, and liquid resistance testing for the three types of hoses, R7/R8/R18. A comparative analysis of the main technical changes between the 2021 version and the previous version of the standard is also provided.
Standard Overview
DIN EN ISO 3949:2021 specifies the technical requirements for three types of textile-reinforced thermoplastic hoses and hose assemblies, suitable for hydraulic systems with a working pressure of up to 21 MPa.
- The volume change range of the water-based liquid test is adjusted from 0%~25% to -15%~35%
- The volume change range of the water resistance test is adjusted from -10%~25% to -15%~35%
- Correct the labeling error of R18 hose in Table 6
Core Parameter Comparison
| Parameters | R7 Type | R8 Type | R18 Type |
|---|---|---|---|
| Maximum Working Pressure (MPa) | 7.0-21.0 | 14.0-42.0 | |
| Burst Pressure (MPa) | 28.0-84.0 | 56.0-168.0 | 84.0 |
| Impulse Test Pressure | 125% Working Pressure | 133% Working Pressure | 133% Working Pressure |
Key Performance Requirements
1. Dimensions and Tolerances
Hose nominal inner diameter 3.2-25mm, concentricity requirements:
- ≤6.3mm: wall thickness fluctuation ≤0.8mm
- 6.3-19mm: ≤1.0mm
- ＞19mm: ≤1.3mm
2. Physical Properties
Liquid Resistance Test Requirements:
- Oil resistance test (ISO 1817): 100℃×72h, volume change -15%~35%
- Water-based liquid test: 70℃×168h, volume change -15%~35%
- Water resistance test: 70℃×168h, volume change -15%~35%
3. Electrical Properties
Class 2 hoses must pass the 37.5kV AC withstand voltage test, with a leakage current ≤50μA
Implementation Recommendations
Key Points for Quality Control
- Production testing shall be carried out every 3000 meters or 12 months (whichever comes first)
- Type testing shall be repeated every 5 years or when the material/process is changed
- Marking is prohibited on the outer surface of Class 2 hoses
Marking Specifications
The hose shall be marked at least every 760mm:
Manufacturer/ISO 3949/Type-Grade/Nominal Size/Working Pressure (MPa)/Production Quarter
Example: XXX/ISO 3949/R7-2 NON-CONDUCTIVE/16/10.5MPa(105bar)/2Q21