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NATURE OF SOLID POLLUTANTS
The main pollutants found on examining hydraulic fluids are :
- silica (sand…)
- metallic material
- residue of plastics, fabrics and fibres of all kinds.
In general silica comes from outside the circuit inside (equipment operating out of doors),
unless it is original pollution due to sandblasting, which is definitely not recommended in
hydraulics.
"Mat" metallic material i.e. corroded material, often represents external pollution, whilst shiny
particles usually come from wear on the inside of the circuit.
Residue of plastics, or similar, such as pieces of seals, plugs, rags, sealer tape (Teflon) etc.
are almost always original pollution from when the equipment was made.
This type of pollution can also come from various topping up and oil change operations carried
out in inadequate conditions.
TYPES OF PARTICLES.
a) Coarse pollution
This corresponds to particles whose size is above 15
µ
m
(15
µµµµ
m =15 millionths of a metre = 0.000015 m = 0.015 mm).
The value of 15
µ
m represents the average value of the clearance found in industrial
hydraulics. When taking into account the effects of coarse pollution this value should be
lowered for the small calibres. For example, a control valve slide 10mm in diameter is mounted
with a clearance of about 8
µ
m.
The consequences of coarse pollution are as follows :
Coarse
pollution
Seizure
Instant
phenomenon
Equipment
stops
High
financial
cost
Summary of Contents for HYDRO 124D
Page 1: ......
Page 2: ...2...
Page 4: ...4 GRASSBOX...
Page 5: ...5...
Page 8: ...8 POWER CURVES CONSUMPTION TORQUE LUBRICATION...
Page 9: ...9 AIR SUPPLY CIRCUIT COMBUSTION AIR FILTER...
Page 11: ...11 ENGINE HOT...
Page 17: ...17...
Page 48: ...48 OIL RETURN FILTER H124D...
Page 50: ...50 DRIVE TRANSMISSION CIRCUIT HYDRAULIC DIAGRAM...
Page 51: ...51...
Page 52: ...52...
Page 71: ...71...
Page 73: ...73...