MACHINERY LUBRICATION- INDIA SEPTEMBER-OCTOBER 2019 | Page 22

HYDRAULICS
and actuators.
A flushing unit can be used to remove solid
contaminants and water from the oil.
employed, be sure it is recommended
for hydraulic systems. Even small
amounts of the wrong solvent can
impair certain additives.
System flushing is done by connecting
the inlet and outlet lines of the cylinders
and motors. If possible, electrically or
manually actuate the directional valves
to allow the fluid to recirculate through
the piping. If this is not possible, bypass
the directional valves by connecting the
pressure and tank lines to the outlet
lines of the actuators. Utilize the
machine’s existing pump to recirculate
oil through the lines. Connect a high-
velocity flushing unit so it recirculates
oil in the reservoir through the filters
during the flushing process. Allow the
system to run for as long as possible.
Verify the Reservoir
Heater Setting
System Cleaning
and Flushing
When oil is removed from the reservoir,
it should be filtered going into a storage
tank with a flushing and filtering unit,
which can remove solid contaminants
and water. Use a quality, high-capture-
efficiency filter (ISO 16889) that
matches the target cleanliness level of
the system. Unless the oil is severely
degraded, it is not necessary or even
desirable to change it.
After the reservoir is cleaned, run the oil
through the filters while refilling. The
entire system should then be flushed to
clean the oil in the lines to the valves
Many times the heater is disconnected
during the summertime or may have
been omitted from the reservoir when it
was initially built. Check the heater
thermostat on the reservoir to confirm
that it will turn on at a minimum of 70
degrees F. If the pump is mounted on
top of the reservoir and the oil
temperature drops below approximately
60 degrees F, then some cavitation of
the pump may occur. location, the breather cap may need to
be changed a couple of times a year.
Many breathers have a mechanical
indicator that will provide a visual
indication when the element is dirty.
Other options include pressurizing the
reservoir with an internal bladder or
using a moisture-removal type of
breather. Remember that money spent
upgrading your breather cap is never
wasted.
Adjust Oil Level Switches Set High-temperature
Switch
Most reservoirs utilize two switch
settings — warning and shutdown. The
problem is that the difference between
these two levels may be several hundred
gallons of oil. By eliminating the warning
switch and setting the shutdown at a
higher level, oil loss will be minimal if a
hose ruptures.
Check the Breather Cap
Oil purity is shown for a system before it was
flushed (left) and then after one, four and 16
hours. This particular system had high water
content prior to flushing.
20 | September - October 2019 |
By performing
these tests,
your systems
will operate
safer and at
maximum
efficiency
while reducing
unexpected
downtime.
The breather cap is usually the most
neglected component on the reservoir.
Verify that the breather cap filter has a
capture efficiency that matches the
target fluid cleanliness. This is the first
line of defense for contaminants
entering the tank. Depending on the
www.machinerylubricationindia.com
Mineral oil will begin breaking down at
140 degrees F, but many systems will
not shut down the unit until the oil
temperature reaches 160 degrees F.
Hydraulic systems are designed to
operate below 140 degrees F. For every
15 degrees F that the oil increases above
140 degrees F, the life of the oil will be
cut in half. If the oil temperature rises
above that level, then a problem exists
in the system. This could be caused by a
cooler malfunction or excessive
bypassing at the pump. Set the high-
temperature switch at 140 degrees F to
shut off the pump, preventing oil
breakdown.