Influence of the working conditions on the metal hose design

In view of the variety of the different applications the working pressures and bending radius stated in the technical tables can only be used as a guideline. Predominantly they are valid for statical stress and room temperature (20°C). The pressure values provide a minimum of four times the safety factor to the burst pressure in acc. with ISO 10380. The usual test pressure is at 1.3 times the working pressure, unless the user specifies a higher pressure for testing. The existing working conditions (i.e. pulsating and discontinuous demand, type and frequency of motion, higher working temperature etc) exert additional demands on the hose material. These influences can be taken into account in favour of the working safety and working life by the following tables and diagrammes. 

Single motion
Minimum bending radius for single motion tested according to ISO 10380 7.4.2 - picture 2.

Repeated motion
For repeated motion without major dynamic demand.

Dynamic motion
For dynamic motion the radius  Rb is to be re-calculated according to the table using the corrective factors ft and fdyn.

The allowed working pressure is calculated as follows:

P zul. = Allowed working pressure (bar)
PT     = Working pressure acc. to table (bar)
ft       = Safety factor for increased  temperature (without dimension)
fdyn   = Safety factors for dynamic stress (without dimension)

The allowed bending radius is calculated as follows:  

Rdyn. = Bending radius for dynamic stress (mm)
Rb     = Bending radius for repeated motion acc.to table (mm)
ft       = Safety factor for increased temperature (without dimension)
fdyn.  = Safety factor for dynamic stress (without dimension)