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...

1. 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.
2. "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
3. "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
4. "Reliability and maintainability are a function of contamination control and contamination control leads to long life." - ARBURG Injection Moulding
5. "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 :

1. From within the system.
2. 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.

Top of Page ^

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.

Top of Page ^

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.

Top of Page ^

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

Top of Page ^