Page 10 - Parker - The Handbook of Hydraulic Filtration

Contamination Types and Sources

Filtration Fact Damage is reached, ice crystals form, adversely
▼ Corrosion of metal surfaces
A simple ‘crackle test’ will ▼ Accelerated abrasive wear affecting total system function. Operating
functions may also become slowed or
tell you if there is free ▼ Bearing fatigue
erratic.
▼ Fluid additive breakdown
water in your fluid. Apply a
▼ Viscosity variance Electrical conductivity becomes a pro-
flame under the container.
▼ Increase in electrical conductivity blem when water contamination weakens
If bubbles rise and ‘crackle’
the insulating properties of a fluid, thus
from the point of applied Anti-wear additives break down in the decreasing its dielectric kV strength.
presence of water and form acids. The
heat, free water is present
combination of water, heat and dissimilar
in the fluid.
metals encourages galvanic action. Pitted
and corroded metal surfaces and finishes
Filtration Fact result. Further complications occur as
temperature drops and the fluid has less
ability to hold water. As the freezing point
Hydraulic fluids have the
ability to ‘hold’ more water

as temperature increases.
A cloudy fluid may become

clearer as a system
heats up.

Typical results of pump wear due to particulate and water contamination

8