Factors influencing the choice of the appropriate hydraulic hose
Hydraulic hose lines are used to transmit power by means of oil pressure and consist of flexible hydraulic hoses that are fitted with force-locking and form-fitting connection fittings at both ends.
Choosing the right hydraulic hose for your application is influenced by a variety of factors.
You can find out here which factors have to be taken into account in detail:
1. regulations
Legal and other regulations must be observed with special care when using hydraulic hose lines and the manufacturer must be informed of them at the time of the inquiry.
2. hose line size
The required inner diameter of a hose line is determined by the intended operating pressure and the conveying speed.
Do not dimension too small!
Hose lines that are too small in size result in a high flow rate of the medium, causing considerable pressure losses, noise and increased temperatures as a result of turbulent flow. This harms the entire system.
If, in exceptional cases, undersized valve connections require smaller hose diameters, we recommend using adapters in step sizes to make the transition to the correctly sized hose line.
3. dynamic operating pressure
In practice, hydraulic hose lines are mainly subjected to dynamic loads and are designed to withstand the maximum permissible operating pressure specified for the respective hose types and dimensions.
Safety factor 4:1
As a rule, the operating pressure is one-fourth of the determined or specified burst pressure. This safety factor of 4:1 complies with SAE, DIN and EN regulations.
Dynamic operating pressures are the predominant load type of hydraulic systems. Purely static loads are the absolute exception; for this reason, the specification “static operating pressure” has been removed from the sets of standards, since this is only of theoretical significance.
Observe pressure peaks!
For systems where pronounced pressure peaks occur, a hose with a higher pressure rating in relation to the actual operating pressure of the equipment should be selected.
4. burst pressure
The data on burst pressure are minimum values, and apply only to hose assemblies that are still unused.
For the user, the burst pressure of a hose or hose assembly may only have theoretical significance. Taking into account the safety requirements to be met by each plant, this may never – even approximately – be achieved in practice.
It is a mistake to assume that comparable hoses from different manufacturers will have a longer service life under the same operating conditions the higher the value specified for the burst pressure. Only the dynamic pressure values are relevant for the designer!
5. high pressure gas systems
Should you wish to install a hose line in your high pressure gas system, please note that these systems are dangerous and require regular inspections.
Due to the increased risk potential, the hose assemblies must be protected against mechanical damage as well as chemical and environmental influences. They must also be secured during installation so that the hose cannot whip in the event of a defect. In any case, when conveying gaseous media, the outer rubber must be perforated.
6. temperature
The operating temperatures specified for hoses refer to the maximum temperature of the medium, whereby the ambient temperature must also be taken into account.
Continuous operation at high temperatures can affect the service life of the hose assemblies as well as the secure seating of the fittings.
The temperature resistance of a hydraulic hose also depends on the medium. Hose assemblies can therefore not be used for all media in the specified temperature range.
In special cases of application we ask for your inquiry.
If hydraulic hose lines are not continuously stressed to the limit in terms of operating pressure, bending radius and temperature of the medium and the environment, a much longer service life can be expected.
7. length changes
Length changes occur in every hose under pressure load.
According to the standard, these values may be between -4% and +2% at maximum operating pressure. When determining the nominal length of a reinforced hose assembly, this change in length must be taken into account – on a case-by-case basis.
8. chemical resistance
When selecting a hose assembly, it is also important to consider the chemical resistance of the hose core in relation to the type, concentration and temperature of the medium, the ambient temperature and the duration of exposure.
In principle, the hose core is resistant to mineral or synthetic oil-based hydraulic fluids, glycol-water mixtures and oil-water emulsions in the specified temperature range, but not to phosphate-ester fluids (HFD).
Further details regarding resistance to various other media can be found in the resistance list.
However, this table can only be considered as a guideline for chemical resistance. In case of doubt and possible influence of the medium on the outer rubber, please contact us.
9. bending radius
The specified minimum bending radii apply to the permissible maximum operating pressure with the hose assembly unmoved.
If the recommended minimum bending radius is not achieved, the service life of hose assemblies will be impaired. In this case, the operating pressure must be reduced.
10. storage
Proper storage extends the service life of hydraulic hoses. The storage room should be cool (up to +20°C), dry (relative humidity max. 65%) and protected from sunlight.
Ozone and UV exposure affect the service life of the hose.
In each case, the oldest hoses or lines in stock are to be used first. (The storage time should not exceed 4 years for hoses and 2 years for hose assemblies). For more details, see DIN 7716.
We will help you!
Please feel free to contact our experts in the office and in the field, who will be happy to help you select the right hydraulic hose for your application at any time.
In our online store you will find the right hydraulic hose for you from our extensive selection.
You can find out how to determine the correct hose length here.
How to correctly mark a hose assembly, you will learn here.
Here we show you how to install hydraulic hoses correctly.
