Short answer
A constant pressure hose family means that the sizes within a defined product scope are offered according to a common working pressure class. It does not mean the pressure is kept constant inside the hose by itself. Temperature, impulse class and hose assembly limits still apply separately.
Source: S011
Technical explanation
ISO 18752 is an important reference for hydraulic hose types defined by pressure classes and performance requirements. Having the same pressure class does not show that all hoses have the same outside diameter, minimum bend radius or temperature performance. In addition, the limits of the fittings and other components in the hose assembly must also be met. It is not correct to extend the constant pressure approach of one product family to all sizes of another manufacturer.
Source: S011
Topic-specific checkpoints
| Item | Description |
|---|---|
| Pressure class | A common classification for a specific series and scope. |
| Performance class | The relevant type/grade distinctions of the standard and the product declaration. |
| Size-dependent data | Outside diameter, radius, weight and flow cross-section. |
| Assembly limit | All components and conditions are assessed together. |
Source: S011
How is it assessed in practice?
If a constant pressure series is being considered to simplify inventory, first list the machine groups and the sizes needed. Check the connection system and the assembly envelope separately for each size. This way, while standardizing the pressure class, you do not overlook unsuitable ends or installations. In the technical table, keep 'family class' and 'permitted operating condition of this assembly' in separate columns; do not let the value of one be copied automatically to the other.
Original editorial recommendation; not a clause of a standard.
Frequently asked questions
Does a constant pressure hose behave like a pressure regulator?
No. The term describes a product classification. Pressure control of the system is provided by the pump, valves and other design components; the hose class does not take over their function.
Source: S011
Source coverage
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S011
ISO 18752:2025 ISO · accessed 2026-10-19 Abstract; General information; Life cycle