HYDAC FILTER SYSTEMS GMBH
Mounting/installing | 5
MoWa OLFP-3-6 3819798a en-us
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5.3 Observing/calculating pressure loss
The pressure loss in a hydraulic line depends upon:
– Flow
– Kinematic viscosity
– Pipe dimensions
– Fluid density
The pressure loss can be estimated as follows for mineral oil-
based hydraulic oils:
Fig. 17:
Pressure loss formula
Δp Pressure differential
[bar]
L Line length
[m]
d Internal pipe diameter
[mm]
Q Flow
[l/min]
ν Kinematic viscosity
[mm²/s]
D Density
[kg/dm³]
The mineral oil-based hydraulic oil has a density of ≈ 0.9 kg/
dm³.
This formula applies to straight pipe runs. Particularly with re-
gard to the suction side connection, note that additional con-
nectors and pipe bends increase the pressure differential.
Observe the following points for hydraulic connection:
– Keep the height difference between the pump and the oil
level in the reservoir as small as possible.
– Use a suction hose that is suitable for a vacuum of ≥
-0.5 bar.
– Avoid constrictions in the connected hoses. This reduces
the power and increases the risk of cavitation.
– Note that the nominal size of the connected hose/piping
must correspond to the cross-section of the connection
thread.
