Filtration System - Danfoss LPV Technical Information

Technical Information
LPV Axial Piston Pumps
System design parameters

Filtration system

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Filter βx-ratio is a measure of filter efficiency defined by ISO 4572. It is defined as the ratio of the number of particles greater than a
given diameter ("x" in microns) upstream of the filter to the number of these particles downstream of the filter.
© Danfoss | September 2017
Fire resistant fluids are also suitable at modified operating conditions. Please see Hydraulic Fluids and
Lubricants Technical Information, 520L0463, for more information. Refer to Experience with Biodegradable
Hydraulic Fluids Technical Information, 520L0465, for information relating to biodegradable fluids.
The following hydraulic fluids are suitable:
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Hydraulic Oil ISO 11 158 - HM (Seal compatibility and vane pump wear resistance per DIN 51 524-2
must be met)
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Hydraulic Oil ISO 11 158 - HV (Seal compatibility and vane pump wear resistance per DIN 51 524-3
must be met)
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Hydraulic Oil DIN 51 524-2 - HLP• Hydraulic Oil DIN 51 524-3 - HVLP
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Automatic Transmission Fluid (ATF) A Suffix A (GM)
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Automatic transmission fluid Dexron II (GM), which meets Allison C-3 and Caterpillar TO-2 test
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Automatic transmission fluid M2C33F and G (Ford)
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Engine oils API classification SL, SJ (for gasoline engines) and CI-4, CH-4, CG-4, CF-4 and CF (for diesel
engines)
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Super Tractor Oil Universal (STOU) special agricultural tractor fluid
To prevent premature wear, ensure only clean fluid enters the hydrostatic transmission circuit. Danfoss
reccommends a filter capable of controlling the fluid cleanliness to ISO 4406 class 22/18/13 (SAE J1165) or
better, under normal operating conditions.
Filtration strategies include suction or pressure filtration. The selection of a filter depends on a number of
factors including the contaminant ingression rate, the generation of contaminants in the system, the
required fluid cleanliness, and the desired maintenance interval. Select filters to meet the above
requirements using rating parameters of efficiency and capacity.
You can express measured filter efficiency with a Beta ratio
transmissions and open circuit transmissions with return line filtration, a filter with a β-ratio within the
range of β = 75 (β ≥ 2) or better should be satisfactory. For some open circuit systems, and closed
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circuits with cylinders being supplied from the same reservoir, we recommend a considerably higher
filter efficiency. This also applies to systems with gears or clutches using a common reservoir. These
systems typically require a charge pressure or return filtration system with a filter β-ratio in the range of
β = 75 (β ≥ 10) or better.
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Because each system is unique, only a thorough testing and evaluation program can fully validate the
filtration system. Please see Design Guidelines for Hydraulic Fluid Cleanliness Technical Information,
520L0467 for more information.
Ensure fluid entering pump is free of contaminants to prevent damage (including premature wear) to the
system. LPV pumps require system filtration capable of maintaining fluid cleanliness at ISO 4406-1999
class 22/18/13 or better.
Consider these factors when selecting a system filter:
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Cleanliness specifications
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Contaminant ingression rates
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Flow capacity
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Desired maintenance interval
Locate filter either on the inlet (suction filtration) or discharge (charge pressure filtration) side of the
charge pump. Either strategy is applicable for LPV pumps.
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(βX). For simple suction-filtered closed circuit
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