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Filters
Pressure Hydraulics has developed the filtration expertise to
provide a full service in Hydraulics. This includes design
consultancy, equipment supply and manufacture, service and
installation, condition monitoring, flushing of systems.
As distributors for the worlds leading filter manufacturers
Pressure Hydraulics can offer access to the latest filtration
technology. It is important to see filtration as a benefit
rather than a cost and the following are examples of industry
comments;
What the Industry is saying...
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With over 70% of hydraulic failures known
to be due to poor fluid condition, there is a clear need for
a more systematic approach to contamination control." -
PALL
Filtration.
-
"Users should be encouraged to regularly monitor the dirt
levels of the oil as this is the only way that a check can
be made on whether the correct filtration level has been
specified or the filter is working correctly." - REXROTH
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"Contamination is a prime enemy of industrial hydraulic
systems. Controlling it could mean elimination of more than
half of all the servo valve failures." - MOOG
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"Reliability and maintainability are a function of
contamination control and contamination control leads to
long life." - ARBURG Injection Moulding
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"Effective filtration in hydraulic systems prevents
breakdowns and at the same time increases the life
expectancy of important and expensive components". -
HYDAC
As Irish Distributors for Rexroth, Pall, Moog, and Hydac,
Pressure Hydraulics can fully confirm the reality of the above
statements.
Suppliers of Filtration Products From...
Sources and Effects of Particle Contamination
It is necessary to appreciate where this destructive
contamination comes from but there are basically two sources :
- From within the system.
- From outside the system.
Contamination from within the system
By its very nature a hydraulic system consists of many moving
parts; some are moving at slow speed, some at high speed, some
are at high pressure, some at low pressure, some are hard
materials, some are soft materials. All these parts are going to
wear over time no matter how good the components.
The wear generates particles in the fluid and these particles
(if left unfiltered) will help to generate more wear and more
particle contamination. It should be noted that small particles
do the most damage over time so it is important to have good
filtration.
Within the system another source of contamination can arise from
manufacture. Debris and dirt may have been in the system during
installation or manufacture.
For this reason a new system should always be flushed (consult
Pressure Hydraulics) before going into service.
Within the system the oil itself may not be to the required
cleanliness level. Consider that a new barrel of oil is only
filtered to 80 micron and a very ordinary hydraulic system will
have 10 micron filters specified. To overcome this problem oil
filling or topping up should always be done through a filter
transfer unit (available from Pressure Hydraulics).
Maintaining the oil at a suitable cleanliness level can be
helped by having a "by pass type" filtering system permanently
on the system. This is a filter unit that circulates the
reservoir oil through a filter continuously.
For machines that have expensive down time implications this is
very highly recommended and we can offer special filter products
for this application.
Contamination from Outside the system
When a hydraulic systems is operating, oil is being moved around
a circuit. This causes the oil level in the reservoir to rise and
fall, or in other words to breath. It is essential for the
reservoir to be able to breath, and draw in air as the oil level
falls and let the air out as the oil level rises.
Failure to do so could cause a vacuum in the reservoir with
damage to the pump, or pressurise the reservoir which would be
dangerous. For this reason the reservoir will be fitted with a
breather BUT the filter in the breather must be kept clean for
it to function.
Oil reservoirs will also have a filling cap to be used for
topping up or filling. It is important that during this
operation dirt is not allowed to fall into the reservoir.
Remember this should be done through an oil filter pack.
Contamination can also enter the system through worn seals on
cylinders, rods, pump seals, motor seals, and quick release
couplings. If oil is leaking from a cylinder rod seal during the
cylinder out stroke, it will mean that contamination is being
sucked in during the in stroke.
It must be remembered that contamination is not only physical
particles as it can also be air or water which are not meant to
be in the oil. Although air will sometimes work itself out of a
system, water will not and can do serious damage as well as
affecting the performance of the system.
Some examples of water contamination problems :
- Breakdown of the fluid e.g. oxidation
- Reduced lubrication qualities.
- Increased metal surface fatigue
- Corrosion
- Loss of dielectric strength
Some examples of air contamination problems :
- Foaming of the oil
- Slow and erratic system movements
- Reduction in system stiffness
- Higher fluid temperature
- Cavitation and pump damage
- Oil oxidation
Problems maintaining pressures
Maintaining the temperature within the working specifications is
very important as already mentioned. Excessive temperatures will
lead to carburisation of the oil and a layer of "black" will be
found in the tank. This will rapidly destroy components and
filters themselves. Where there may be local "hot spots" in a
system the oil may form a gel on components leading to sticking
valves (e.g. in servo systems).
Solutions to Contamination Problems
HSP Portable Oil Purifier
 The PALL HSP (Hydraulics Spinning Disk) purifier has been
developed as a conditioner for hydraulic and lubrication fluids.
It removes 100% of free water and up to 80% of dissolved water.
The unit is also fitted with a particle filter for removal of
dirt.
It is portable, for moving between different systems or
permanently hooked up. In addition to selling new units Pressure
Hydraulics also has a unit for hire. Email
filters@pressure-hydraulics.com
for more information.
Oil Analysis
Oil Analysis Pressure Hydraulics can carry out particle analysis
on-site or in our Carlow laboratory. Trending can provide useful
condition monitoring.
Hydac Filter Trolley Filter units are available either portable
or on wheels with 3 phase or 110v or 24v DC supply
Pressure Hydraulics can also supply...
- Replacement Elements
- Pressure and Return Line Housings
- Oil Particle Count Analysis
- Clogging Indicators
- Filtration Units
- Ultrasonic Cleaning
- Servo & Proportional Valve Filters
- Lubrication and Heavy Oil
Filters
- Condition Based Monitoring
- Worldwide Sourcing of Elements
Installed
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