Hydraulic Fluid Power. Andrea Vacca

Hydraulic Fluid Power - Andrea Vacca


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0.04 2 0.01 0.02 1 0.005 0.01 0

      Example 2.3 Solid contamination of a hydraulic oil according to the ISO Standard

      Determine the contamination level, in terms of particles per milliliter of fluid, of a hydraulic oil with a code 20/16/13 according to the ISO 4406.

      The ISO 4406 fluid specification, ISO 20/16/13.

      Find:

      The particle count, per milliliter of fluid.

      Solution:

      The answer is straightforward, after understanding Tables 2.7 and 2.8. In particular, per each ml the given fluid has:

       from 5000 to 10 000 particles larger than 4 μm;

       from 320 to 640 particles larger than 6 μm; and

       from 40 to 80 particles larger than 14 μm.

      Source: Assofluid [11] and Parker Hannifin [28].

Low pressure (<70 bar) Medium pressure (between 70 and 130 bar) High pressure (>130 bar)
Pumps
Gear pumps 21/18/16 20/17/15 20/17/14
Vane pumps fixed displacement 20/18/15 19/17/14 18/16/13
Vane pumps variable displacement 19/16/14 18/15/13 17/14/13
Piston pumps fixed displacement 19/17/15 18/16/14 17/15/13
Piston pumps variable displacement 18/16/14 17/15/13 17/14/12
Actuators
Vane motors 20/18/15 19/17/14 18/16/13
Axial piston motors 19/17/15 18/16/14 17/15/13
Radial piston motors 20/18/16 19/17/14 18/16/14
Orbital motors 21/19/17 20/18/15 19/17/14
Cylinders 20/18/15 20/18/15 20/17/14
Valves
Check valves 20/18/15 20/18/15 20/18/15
Pressure and flow control valves 19/17/14 19/17/14 19/17/14
Directional control valves – on/off 20/18/15 20/18/15 19/17/14
Directional control valve – proportional 18/15/13 17/15/12 17/14/11
Servo valves 17/14/12 16/13/11 16/12/10
Cartridge valves 20/17/15 19/17/14 19/16/13

      The reader should know that there are different types of filter available on the market: each one can apply a different filtration technology, have a particular construction type, or integrate other accessories. Illustrating the details and the operating features of the different types of filters is beyond the scope of this chapter. A high‐level description of the available options for filters is provided in [11, 28].

      2.8.2 Filter Placement

      It is important to comment on the application of filters in hydraulic circuits, since there are different alternative options. In general, filters can be classified based on their location in the circuit:

      1 Suction filters (Figure 2.15) are placed between the reservoir and the pump inlet, which is usually the first component of the hydraulic system crossed by the hydraulic fluid after the tank.

      2 High‐pressure filters (Figure 2.16) are placed right after the pump outlet, before the working fluid can reach the control elements and the actuators of the hydraulic system.

      3 Return filters (Figure


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