Other Operating Conditions; Oil; Particle Content, Degree Of Contamination; Filtration - Danfoss PVG 32 Technical Information

Technical Information
PVG 32 Proportional Valve Group

Other operating conditions

Oil

Particle content, degree of contamination

Filtration

© Danfoss | August 2017
The main duty of the oil in a hydraulic system is to transfer energy. It must also lubricate the moving parts
in hydraulic components, protect them against corrosion, and transport dirt particles and heat out of the
system. It is therefore important to choose the correct oil with the correct additives. This gives normal
operation and long working life.
Mineral oil
For systems with PVG 32 valves Danfoss recommends the use of mineral-based hydraulic oil containing
additives: Type HLP (DIN 51524) or HM (ISO 6743/4).
Non-flammable fluids
Phosphate-esters (HFDR fluids) can be used without special precautions. However, dynamic seals must be
replaced with FPM (Viton) seals. Please contact the Danfoss Sales Organization if the PVG 32 valve is to be
used with phosphate-esters.
The following fluids should only be used according to agreement with the Danfoss Sales Organization
for:
•
Water-glycol mixtures (HFC fluids)
•
Water-oil emulsions (HFB fluids)
•
Oil-water emulsions (HFAE fluids)
Biodegradable oils
PVG 32 valves can be used in systems with rapeseed oil. The use of rapeseed oil is conditioned by:
•
complying with the demands on viscosity, water content, temperature and filtering etc. (see chapters
below and technical data).
•
adapting the operating conditions to the directions of the oil supplier.
Before using other biodegradable fluids, please consult the Danfoss organization. Oil filtration must
prevent particle content from exceeding an acceptable level, i.e., an acceptable degree of contamination.
Maximum contamination for PVG 32 is 23/19/16 (see ISO 4406. Calibration in accordance with the ACFTD
method). In our experience a degree of contamination of 23/19/16 can be maintained by using a filter
fineness as described in the next section.
For more information, please see the Danfoss literature:
•
Design Guidelines for Hydraulic Fluid Cleanliness Technical Information, 520L0467
•
Hydraulic Fluids and Lubricants Technical Information, 521L0463
•
Experience with Biodegradable Hydraulic Fluids Technical Information, 521L0465.
Effective filtration is the most important precondition in ensuring that a hydraulic system performs
reliably and has a long working life. Filter manufacturers issue instructions and recommendations. It is
advisable to follow these.
System filters
Where demands on safety and reliability are very high a pressure filter with bypass and indicator is
recommended. Experience shows that a 10 µm nominal filter (or finer) or a 20 µm absolute filter (or finer)
is suitable. It is our experience that a return filter is adequate in a purely mechanically operated valve
system. The fineness of a pressure filter must be selected as described by the filter manufacturer so that a
particle level of 23/19/16 is not exceeded. The filter must be fitted with pressure gauge or dirt indicator to
make it possible to check the condition of the filter. In systems with differential cylinders or accumulators
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