How much pressure do we lose in 100 meters of hydraulic pipe?

How much pressure do we lose in 100 meters of hydraulic pipe?
There may be situations where feeding multiple valve blocks with a large power unit is advantageous over installing a separate power unit for each valve block. In such facilities, pressure hydraulic lines, pilot pressure lines or low pressure return lines may inevitably have to travel many meters. In order to carry the fluid in the pipe from one point to another, we have to overcome the frictional resistances, even horizontally. As a natural result of this, the pressure of the fluid entering the pipe will be higher than the pressure of the exiting fluid, and our lost pressure energy will turn into heat energy. So, how can we determine how much pressure we will lose in the pipes in such a case, let's examine it now.
How much pressure do we lose in 100 meters of hydraulic pipe?
We need many parameters to answer this question. What is the diameter and material of the pipe? What is system flow? Is there a level difference between the starting point and the ending point? What are the physical parameters of the transported fluid? We need to know all this, so unfortunately it is not possible to make a short calculation such as x bar pressure in 10 meters of pipe and 10x bar pressure loss in 100 meters of pipe.

Now let's set the parameters for a simple example;
Place to be used: Pressure Line - oil temperature 40 °C
Fluid to be used: ISO VG 46 Mineral oil (at 40 °C ѵ = 46 mm²/s)
Pipe inner diameter: 30 mm
System flow: 120 lt/min
If the pipe cross-sectional area is calculated for a pipe with an inner diameter of 30 mm and the system flow rate in mm³/s is substituted in the continuity equation on the left, the intra-pipe fluid velocity is found.
In-pipe flow rate: 2830 mm/s
Reynolds number is calculated according to this calculated pipe flow rate and 46 mm²/s viscosity value.
Reynolds number: 1865 (unitless)
Since the calculated Reynold value is less than 2300, the type of flow that will occur in the pipe is laminar, layered flow.
Fluid density: 891 kg/m3
Pipe length: 100 m
Pipe diameter: 0.03 m
Fluid velocity: 2.83 m/s
If the above values ​​are substituted in the formula, the pressure loss is
It is found as ΔP=478280 Pascal => ΔP= 4.78 Bar.
As can be seen, the pressure losses inside the pipe depend on many variables, and in our example, there is a loss of around 100 meters of 5 bar, but if the pipe diameter or system flow rate is different, we may encounter much larger or smaller pressure losses. Another point we should not forget while making these calculations is that local losses are not included in the calculation. Calculation has been made for a straight pipe. If there are elbows, turns at various angles, T connections or any valve on the line, the resistances they will create must be calculated separately and added to the pressure loss.