Etesia HYDRO 124D, Technical Training Manual

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OILS
OILS OILS
OILS
Introduction
The fluid used to transmit the hydrostatic energy is mineral oil (except in certain cases, when there are problems
of inflammability).
The right choice of a hydraulic fluid is a determining factor in the reliability of the hydraulic transmission.
The hydraulic fluid must meet two essential criteria :
- transmit the energy
- lubricate and protect the moving parts.
These two conditions are linked to a environment specific to each use and to the choice of the components
used to make up the circuit.
- temperature
- operating pressure
- service factor of the installation
- maintenance conditions
- external conditions (humidity)
- technicality of the components
- minimum degree of filtering required
- price of the fluid, etc.
The choice of a good oil is a guarantee of long term operation.
"THE OIL IS THE BLOOD OF THE TRANSMISSION SYSTEM"
PRESENCE OF WATER
The presence of water is harmful to the operation of the hydraulic installations.
Its consequences are :
- Destruction of the oil bath solenoids
- Separation of the additives from the base fluid
- Clogging of the filter cartridges.
- Internal oxidation of the components.
Water in the hydraulic circuit is often due to the variations in temperatures in the tank above the level of the oil
(when a hot tank is moved into a cold place). This phenomenon leads to condensation, especially in
environments with high levels of hygrometry (degree of humidity). The maximum value tolerated in the oil is
0.05% (0.5 ml for 1 litre).
Corrosion
The hydraulic fluid must not attack common metals and must meet certain standards.
Oxidation
Mineral oils must have excellent resistance to oxidation (deterioration or transformation of a medium in contact
with oxygen). This quality is all the more desirable when the fluid works at high temperature with high
performances and pressure shocks.
Performances of hydraulic oils.
The mineral oils used in hydraulic installations must have certain qualities indispensable to the correct operation
of the circuits.
Anti-wear resistance.
Modern hydraulic fluids must satisfy the most severe of hydrostatic operating conditions, in particular as far as
their lubricating power and shearing (resistance of the film of oil between two parts in translation one on the
other) under high pressure are concerned. The oil companies offer mineral oils, categories HM or HV, that meet
these criteria.