Functions of hydraulic oil and the reasons of its contamination.
- To act as an energy transmission
medium.
- To Lubricate internal moving parts
of components.
- To act as a heat transfer medium.
- To seal clearances between moving parts.
If any of
these functions is impaired, the hydraulic system in the equipment/rigs will
not perform as designed. The resulting downtime can cost a lot in Dollar and
increase the operating cost for any rig/operations on field.
Proper
hydraulic fluid maintenance helps to prevent or reduce breakdown maintenance.
This is accomplished through continuous improvement program that minimizes and
removes contaminants.
Hydraulic fluid is expected to create a lubricating film to keep precision parts
separated. Ideally, the film is thick enough to completely fill the clearance between
moving parts. This condition results in low wear rates. When the wear rate is
kept low enough, a component is likely to reach its intended life expectancy.
The actual
thickness of a lubricating film depends on.
1. fluid viscosity,
2. applied load,
3. relative speed of the two surfaces.
So, if
after multiple cycles the oil loses its viscosity or is contaminated. It will
lead to addition friction and wear and
tear.
What harm will the contaminants make?
If not
properly flushed, contaminants from manufacturing and assembly will be left in
the system. These contaminants include dust, welding slag, rubber particles
from hoses and seals, sand from castings, and metal debris from machined
components. Also, when fluid is initially added to the system, contamination is
introduced. During system operation, contamination enters through breather
caps, worn seals, and other system openings. System operation also generates
internal contamination. This occurs as component wear debris and chemical
by-products react with component surfaces to generate more contamination.
What are the types & sources of
Contamination?
There are basically 4 sources of contamination:
1. Built-in- Contamination.
2. Natural Contamination.
3. Ingressed Contamination.
4. Generated Contamination.
While the first three types of
contamination is self-explanatory , there is the further classification of
generation contamination on the basis of how it is generated:
1. Abrasive Wear: Hard particles bridging two
moving surfaces, scraping one or both.
2.Cavitation Wear: Restricted inlet flow to pump
causes fluid voids that implode causing shocks that break away critical surface
material.
3. Fatigue Wear: Particles bridging a clearance
cause a surface stress riser that expands into a spall due to repeated
stressing of the damaged area.
4. Erosive Wear - Fine particles in a high-speed
stream of fluid eat away a metering edge or surface.
5. Adhesive Wear - Loss of oil film allows metal to
metal contact between moving surfaces.
6. Corrosive Wear - Water or chemical contamination
in the fluid causes rust or a chemical reaction that degrades a surface.
Are contaminants visible with naked
eye?
Particle sizes are generally
measured on the micrometer scale. One micrometer (or micron”)
is one-millionth of one meter, or 39
millionths of an inch. The limit of human visibility is approx.. 32μm
micrometers. Keep in mind that most damage-causing particles in hydraulic or lubrication
systems are smaller than 14μm micrometers. Therefore, they are microscopic and cannot
be seen by the unaided eye. To put the sizes in perspective, below are the
sizes of some known objects.
Hence filtration of hydraulic oil is
of prime importance. Minimac System provides an array of the solution in this
regard. What we also do is filter check via our experts for any of your
rig/equipment.
At Minimac Systems we offer Flushing Services and Filter Check Services which ensure a clean system including oil tanks and lines. Book an appointment with our technical expert by clicking on https://www.linkedin.com/company/minimacsystemsprivatetlimited or call +91 8975150700
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