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Oil filtration

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During operation, transformer oil accumulate contaminants, which can form various chemicals. These substances reduce the oil’s performance and are, of course, undesirable.

Operation of the transformer becomes unstable. To prevent this, transformer oil is filtered and purified. Some of the methods are discussed in more detail below.

The first stage of transformer oil purification is mechanical. This is a superficial treatment to remove particulate matter and water. The next step is deeper purification performed in vacuum with heating.

The first two stages are, in fact, preliminary. The main process involves various chemicals.

One of the methods is purification of oil with a 98% sulfuric acid solution.

In comparison to other chemical purification methods, the use of sulfuric acid has a significant drawback. Beside reacting with the contaminants, the acid also adversely influecnes the structure of the oil, making it somewhat unstable. Additional processes are required to resolve that problem.

The nature of selective purification is evident from the title. Speical solvents are introduced into the oil to remove specific impurities.

De-waxing is another widely accepted process. In this process, oil is treated with special solvents: acetone, toluene, bensol etc, to remove solid contaminants.

It should be noted that chemical methods influence oil’s stability, but extend the oil’s service life at the same time.

It should also be remembered that any purification process should end with finishing purification, closing the cycle of oil processing and filtration. This is usually done by contact method.

This means that the oil is mixed with special materials, usually clay or bleaching earth. The materials are then mixed and heated. Heating facilitates acviation of all sorbents in the clay.

These absorbents capture contaminants. Deep filtration separates oil from the clay. When selecting adsorbent, it is necessary to pay attention to the content of moisture. It should be suffucient to make production efficient and to make processed oil compliant with specifications.

The most interesting technology today involves the use of bleaching clays (Fuller’s earth). Globecore manufactures a range of CMM type units for filtration of various oils with the use of Fuller’s earth. The advantages of the design are the ability of multiple reactivation of the sorbent, mobility, simplicity of operation and high quality of the output product.

Downtime is significantly reduced by the ability to reactivate the sorbent without the need for frequent replacement, thus increasing process efficiency.

Flushing of Hydraulic Systems Found in Industrial Equipment and Mobile Machinery

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Hydraulic System Contamination

In accordance with widely accepted industrial standards, preventive maintenance processes that remove contaminates from hydraulic systems can produce the following benefits and results:

  1. The effective Service Life of hydraulic motors, pumps, valves and distribution devices can be doubled.
  2. Hydraulic system warranties can be extended by as much as two years due to the reduction in the risk of hydraulic system component failure during the warranty period.  Fluid purity however, must still be monitored and controlled and the hydraulic system must be cleaned annually.
  3. Equipment downtime is reduced.
  4. The cost of transportation of equipment to repair facilities is reduced or eliminated.

Even if oil and hydraulic filters are changed completely, it still does not guarantee that the hydraulic system will be completely free of contaminants.  Solid particulate matter, can and will, remain in valves, pumps, motors and on the internal surfaces of high pressure hoses.  By introducing certain changes that greatly improve filtration system efficiency, equipment downtime can be significantly reduced because the fluid is purified and contaminates can be removed much more effectively than by a simple oil and filter change.

Studies and practical experience indicate that over 70% of hydraulic system failures occur within the hydraulic drive.  In turn, 50% of the hydraulic drive failures occur due to the presence of solid particles in the hydraulic fluid circulating in the system and the drive.  The high percentage of drive failures is due to the fact that hydraulic drive components rapidly wear down when operating with contaminated liquid.  This leads to a reduction of operating efficiency and an increase of internal energy loss.  Operational costs also rise all due to a lack of timely preventive maintenance.

If Serial Filters are used in the hydraulic system, the concentration of solids in the fluid will be approximately 0.022% by weight.  This is 4.4 times above the acceptable standard.  Particles from 10 to 40 micron in size can constitute up to 50% of the contaminants in the fluid.  These sizes mostly coincide with the clearances between friction surfaces and are therefore, the most dangerous and cause the most wear.

As with serial filters, Main Line Filters also cannot provide the required level of hydraulic fluid purification needed to prevent systems failures by themselves.   The hydraulic drive therefore, must be rinsed by special means or processes.

The importance of a thorough cleaning of the hydraulic drives is because of the high level of precision components found in hydraulic systems that are very sensitive to even small amounts of contamination.  As the system becomes larger, the rate of contamination also becomes larger increasing the need for timely preventive maintenance.

If the equipment is operated in dusty environments, particles of dust will settle on cylinder shafts and will enter the hydraulic drive.  A large portion of contaminates and wear products enter the hydraulic tank through the drain lines and cylinder shafts thereby avoiding the filter system.

A excellent way to improve and maintain the purity of hydraulic fluid is through periodic rinsing and removal of harmful particles.  GlobeCore’s UVR Purification Units are specially designed systems aimed at purification of turbine oil, industrial oil, and transformer oil and have a reputation for versatility and reliability.  They have the ability to purify oils and fluids back to their original new like condition and can even exceed well established quality standards.  The UVR plants, due to their compact design and high level of mobility, can be used at your maintenance facility or offsite at remote locations.  There are no restrictions that limit the use of the UVR systems anywhere there is a need for oil purification services.  The compact design allows GlobeCore to ship the UVR units to anywhere in the world.

While cleaning the system, it should be noted that special detergents can only be used in the beginning stages of the process since any detergent remaining is considered an unwanted contaminant.

Prevention of Contamination

Prevention of hydraulic system failures is only possible if enough attention is paid to the most likely cause of the failures.  It is generally accepted that contaminants are the leading cause of system failures. It is therefore, important to use effective methods of controlling and preventing contamination.  Controlling contamination can help to ensure efficient operation of the system, extend the service life of components, and eliminate malfunctions before costly repairs or unplanned down time is required.

Testing

A daily testing of the hydraulic system allows the operator to quickly localize leaks and other malfunctions before they impact operation.  Periodic checks include checking the pressure in the system, visual inspections, and checking fluid level before, during and after the completion of the work cycle.

Inside the Hydraulic System

Prevention of contamination is very important, but it is equally as important to understand the processes occurring inside the hydraulic system. Regular checking of hydraulic fluid is the best way of localizing part wear and contamination.

Regular sampling

In order to precisely estimate the condition of the hydraulic system, regular sampling of the fluid is required and recommended as part of a comprehensive preventive maintenance program.  It is recommended to take an oil sample for analysis every 500 hours of operation or sooner if the equipment is operated in extreme conditions.  If samples are taken regularly, a certain base line may be established and will allow the operator and maintenance manager to immediately see any deviations allowing for timely corrective action.

Influence of Hydraulic Fluid Contamination on Equipment Wear

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According to recent industry statistics, 70-80% of hydraulic system malfunctions and up to 90% of bearing failures are caused by media contamination.

Types of Contamination and the Long Term Impact

The performance, quality, and purity of operating fluids directly affect the reliability and the service life of pumps, hydraulic drives and various hydraulic equipment installed in mobile and stationary locations.  If high precision hydraulic equipment is used with gaps between moving parts of 5 to 24 microns, then the use of high quality hydraulic fluid that is free from contaminates is a must to ensure continuous trouble free operation of the system.  The effects of contamination on the performance of equipment will vary and depends on the size and composition of the contamination.

The aggressive effects of fluid contamination is detrimental to the reliability and durability of hydraulic systems.  Undesirable consequences may be caused by solid particles carried by the fluid that enter through the gaps in the system.  Contamination will be found on the surfaces of flat friction pairs, valve facets etc.  This unwanted contamination leads to increased wear and equipment failures that include hydraulic lock, clogging of small valves, plunger jamming, loss of valve tightness and other system failures.

Axial-plunger pumps and the control slides of automatic control systems are especially sensitive to fluid contamination.  Solid particles of comparable sizes to the gaps pose the biggest threat to plunger and slide pairs.

Entry of Contaminants into the Hydraulic Systems

There are five ways contaminants can enter hydraulic system:  (1) Through insufficient and improper cleaning of components and parts during manufacture (metal files, remaining abrasives, fragments of construction material etc;  (2) through the introduction of contaminated fluid when initially filling or refilling the system;  (3) through the introduction of contaminants during assembly and repairs;  (4) through the wear and corrosion of parts during normal operation; and (5) from dust and dirt that enters through vents or loose hydraulic tank plugs.

Particle Size

Despite the fact that Solid Contaminants are extremely small, they can still accelerate the aging of oil, cause rapid wear of components, and cause failure and malfunction of operating assemblies.

Gaps in Typical Hydraulic System Components

In modern hydraulic systems, the gaps between components are limited to the range of 1 to 25 microns.  Lately, as technology and machining processes improve, the gaps have been decreasing raising the fluid quality and purity requirements higher and higher.

Contamination reduces the reliability of hydraulic equipment and accelerates its wear and shortens effective service life.  Hence the reason research into the most efficient ways of purification has been part of the industry for decades.  GlobeCore is a leader in research and development of purification systems that are efficient and protect the environment.

Purification

GlobeCore offers a line of UVR vacuum purification systems that are designed for purification of hydraulic fluid, turbine oil, industrial oil, mineral oil, compressor oil, and transformer oils.  The UVR units are built around a vacuum and adsorbent treatment process.  These systems can also lighten the product appearance and remove paraffins and some sulfur from fuels.

The main advantage of the UVR plants is their economy and versatility (requires no additional adjustments when switching from one product to another since the machine operates in an automatic mode).

GlobeCore is the Industry leader in the manufacture of the highest quality oil purification systems anywhere in the world today.

Hydraulic System Assembly

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Hydraulic System Installation Requirements

During the assembly and installation of hydraulic systems, the first concern is to provide easy access to the components and assemblies.  The service replacement of a system component should not require disassembling of neighboring components and hydraulic drive components.  Hydraulic systems should also not bear the weight of connecting pipes.  Additionally, loads caused by elastic deformation are undesirable and lead to future maintenance problems and should be avoided.

Sufficient pressure of hydraulic fluid should be provided in the hydraulic suction line.  The diameter of the suction line should not be less than the mean diameter of the pump’s suction inlet pipe.  The flow rate of the fluid in the suction line should also be limited to approximately 1.2 meters per second.  The resistance should be minimal with pressure in a range of between 0.02 – 0.025 MPa.  The rate of fluid flow in the drain lines of hydraulic drives with open circulation, should not exceed the flow rate in the suction line.  Otherwise, air and oil emulsion will form in the hydraulic tank when being drained.  The drain outlet should be submerged in the oil at a 45 degree angle.  The minimum clearance of the outlet from the bottom of the tank is calculated as twice the diameter of the drain pipe.

To prevent formation of air pockets, the drain outlets of hydraulic machines should be oriented in an upward direction.  If the drain line is long, its cross section should be increased to prevent pressure build up in the machine.

Connections are made by either flexible steel lines or rubber-metal hoses.  The specifications of the lines or hoses should meet the following requirements:

  • the hoses must not hang or kink;
  • sharp bends or twists are not allowed;
  • the hoses must not rub against each other and other components of the machine during operation;
  • the length of a straight part near the connection must be at least six times the external diameter of the hose.

Air removal devices are installed in the topmost point of the pipes.

Assembly and Installation of Hydraulic Machines and Hydraulic Systems

Assembly is begun by testing all components and parts ensuring that all required parts are present and on hand.  The first parts to be assembled are hydraulic assemblies, connection lines and instrumentation.  Control and cooling systems are next in the assembly process.  During assembly, all openings for the entry and exit of hydraulic fluids must be tightly sealed with plugs.  Purification and etching of internal surfaces of the pipes is mandatory.  Following the purification and etching process, the pipes are rinsed in special baths, dried with hot air and plugged until installation.  To ensure pipe integrity and performance at high pressure, they are tested before installation using twice the normal operating pressure.

The correct installation of sealing materials requires additional attention.  Dents, chips and other damage on the surface of parts for connecting and sealing is unacceptable and will lead to fluids leaks.  The size and cleanliness of contacting surfaces must comply with the existing standards and regulations.

Before installing the seals, a lint-free swab, soaked in benzene, is used to treat the seal surfaces and the surfaces they will make contact with.  Next, the surfaces are dried at room temperature until the benzene evaporates.  Only then can the seals and part surfaces be coated with the operating liquid or a lubricating material neutral to the material of the seal.

Seals must not be warped, stretched, twisted or damaged in any way.  If the sealed components do not have bevels, special assembly arbors are used for installation of seals with uneven or step-shaped parts.

Assembly and dis-assembly of positive displacement hydraulic drives must be done in accordance with the operators manual.

Filling of the System with Hydraulic Fluid

Upon completion of assembly, hydraulic fluid will be placed into the equipment.  Special attention must  be paid as to the correct type and correct amount of hydraulic fluid that will be put into the system.  The fluid must not contain water and solid particles must be removed by special filtration equipment prior to filling.

GlobeCore offers the UVR line of equipment for this purpose and it is based on unique and industry leading technology.  The GlobeCore UVR system is equipped with drying and degassing sections. Solved gases and water are removed from the oil by vacuum and the liquid is filtered.  The remaining contaminants are removed by Fuller’s Earth adsorbents.

The advantage of GlobeCore’s equipment is its versatility.  The UVR systems not only process hydraulic oils, they also process transformer oil, turbine oil, industrial oils, diesel fuel, HFO, kerosene, gas condensate and gasoline.

After using the GlobeCore Process of oil purification, the hydraulic oil is fully restored and is made to comply with and/or exceed industry standards.  After using the GlobeCore Process, your company can confidently avoid the cost of repairs and replacement of components that would have most likely failed due contaminated hydraulic fluid.

Filtration fineness cannot  exceed that of the finest filter in the hydraulic system.  Hydraulic fluid is filled into the system at special filling stations equipped with manual or mechanical drives.  The use of such stations have several obvious advantages.  (1) Availability of a tank protecting the oil from contamination during transportation, storage and filling;  and (2)  input and output fine filters providing the required fineness of filtration.

Filling of a positive displacement hydraulic system can be roughly divided into three stages: (1) The first stage is to fill the oil into the hydraulic system and remove air through the drain system.  The fluid is fed through the assembly line and into the lower drain point of the hydraulic drive.  As liquid enters the system, air is pushed out into the hydraulic tank through the top drain point;  (2) The hydraulic tank is filled to the top level; and (3) the hydraulic system is then topped off with fluid.

After completion of the these three stages, the positive displacement hydraulic drive is tested at idle with minimal rotation speed of the drive shaft.  The tests are repeated every 15 seconds. Hydraulic system filling is controlled by the rate of decrease in the hydraulic tank fluid level.  When the tank is filled, the drive motor is starts to operate at idle speed.  It operates at this speed for 3 to 5 minutes.  The system is then filled with liquid to the required level usually indicated by the mark on the hydraulic tank indicator.

After Assembly; The Rinsing of Pipes with Operating Fluid

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The purging of hydraulic system pipes is vitally important to the proper operation of your hydraulic system equipment.  Purging the pipes ensures that the hydraulic system will have trouble free operation for the duration of its normal service life.  If the purge is not performed, or the duration of the process is not sufficient, premature wear of the internal components will be accelerated.  The system will most likely malfunction and/or fail entirely.  Problems may even occur immediately after being placed into service.

Our company, GlobeCore offers unique equipment that can purify turbine oil, industrial oil, transformer oil and other industrial oils.  Purity of the liquid after treatment in one of the GlobeCore UVR plants complies with and usually exceeds all existing standards.  The GlobeCore Process will help prevent hydraulic systems from failing prematurely and will greatly help to increase the service life of the treated equipment.
In accordance with industry standards, the following positive results can be achieved after purifying hydraulic equipment by removing solid particles, moisture, and other harmful contaminates from the hydraulic fluid:

  1. Double the lifetime of hydraulic motors, valves, pumps and distribution devices
  2. Hydraulic system warranties can be extended by as much as two years due to the reduction in the risk of hydraulic system component failure during the warranty period.  Fluid purity however, must still be monitored and controlled and the hydraulic system must be cleaned annually.
  3. Reduction of equipment downtime for repairs.
  4. Elimination of the cost of transportation of equipment to repair sites.
  5. Reduction of downtime costs.

It should be noted that the common concept that changing the oil and filters removes all moisture and contamination from the hydraulic equipment is simply not true.  Contamination remains in the motors, valves and on the internal surface of high pressure hoses.  Changing the oil is certainly an improvement, but it is an incomplete process that is costly, inefficient and will require repeating more frequently than a true purification process.

With slight modification of the filtration system and the use of special filter elements, equipment down time costs can be reduced significantly.

Recent studies and experience shows that no less than 70% of hydraulic failures occur due to the presence of solid particulate matter in the hydraulic fluid.  This failure rate is even more alarming considering that over 50% of all failures occur in the hydraulic drive system.  If equipment is allowed to operate with contaminated liquid, it will lead to intensive and premature wear of the hydraulic drive components, reduction of efficiency and increased internal energy losses.   The consequences are lost time and increased operating costs.

If Serial Filters are used in the hydraulic system, the concentration of solids in the fluid will be approximately 0.022% by weight.  This is 4.4 times above the acceptable standard.  Particles from 10 to 40 micron in size can constitute up to 50% of the contaminants in the fluid.  These sizes mostly coincide with the clearances between friction surfaces and are therefore, the most dangerous and cause the most wear.

As with serial filters, Main Line Filters also cannot provide the required level of hydraulic fluid purification needed to prevent system failures by themselves.   The hydraulic drive therefore, must be rinsed by special means or processes.

The main method of liquid purification in operating hydraulic equipment is regular purification of the hydraulic fluid by GlobeCore’s UVR plants.

It should be considered that purging of pipelines with special detergents is only sensible at the very first stages. At the time of system assembly and commissioning, the system should be purged with the hydraulic fluid, since using a detergent may lead to additional contamination of the system.

Purification of Hydraulic Fluid used in Excavator Equipment

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Excavator hydraulic systems are powered by hydraulic fluids derived from mineral oils.  Hydraulic fluids operate at constant pressure created by one or more pumps known as “hydraulic prime movers.” This pumping action causes the transfer of energy to actuators, hydraulic motors and hydraulic cylinders.  Besides transferring motion to various parts, the fluids also serve to lubricate friction parts and prevent corrosion.

Since mineral oil must freely pass through hydraulic lines, hydraulic system channels and high pressure hoses, it should be able to maintain the proper viscosity at a range of operating temperatures.  It should also retain its performance characteristics with temperature deviations found in extreme cold and extreme heat climates and with temperature variations that come with the change of seasons.

Another important characteristic of hydraulic fluid is its ability to resist the affects of oxidation and remain stable against chemical reactions with hydraulic system construction materials (bronze, steel, rubber, plastic etc), as well as with other dynamic parameters both in storage and operation.

Manufacturers offer many types of hydraulic fluids for use in various climates and make recommendations on which fluid is best for a particular climate and equipment type.

The above requirements for operating fluids must be observed in the operation and maintenance of your of equipment.  The hydraulic system in any piece of equipment must be able to maintain air tightness to avoid the entry of moisture, dust and other contaminants that will rapidly degrade the quality of the fluids and damage internal parts.

Hydraulic fluids are usually delivered in special barrels or by oil-carrier trucks.  Reputable manufacturers normally guarantee the quality of fresh and unused oils, but it is still in your best interest to test the oils and fluids before use to ensure its absence of contaminates and to ensure that it meets the requirements of your equipment.  Testing is initiated by taking samples of the fluid and performing an analysis.  If the testing and analysis reveal that the oil or fluid does not measure up to the quality standard, or contains unacceptable levels of contaminates, the oil should either be replaced or cleaned.  The manufacturer has a responsibility to provide you with a clean and high quality oil or fluid, but cleaning the oil through an in-house purification process may actually save you time and money over sending the oil back.

GlobeCore has a solution for your company.  GlobeCore’s UVR equipment line of purification units offer high quality purification of mineral oils that comply with the highest quality standards of new oil.  The GlobeCore Regeneration Process restores the oil to new like condition and improves the oil making it more stable and resistant to oxidation.   The GlobeCore Process will ensure the highest efficiency of your excavator equipment during operation and will help to eliminate the costs of unscheduled repairs and component replacement caused by hydraulic fluid contamination.

Fluid and Oil Contamination Problems

The idea that storage of oils and fluids in a clean warehouse will prevent contamination from entering your hydraulic equipment is a dangerous misconception.  Oils and fluids may become contaminated during the filling process or during transportation that may or may not be due to the negligence or incompetence of service personnel.  Oil carrier tanks must also be checked regularly and cleaned of dirt, dust and water, but ultimately you are the one that must ensure uncontaminated oil or fluid is not being placed in our equipment.

Water may enter the oil when filling the hydraulic oil tank when it is raining at the fill location.  Water is a major enemy of hydraulic systems because of the corrosion it creates in the internal parts of the hydraulic system.  Corrosion from water results in contamination of the fluid and changes the composition of the fluid leading to internal damage and performance problems.  For example, the internal surfaces of hydraulic cylinders may form blisters or scratches and may lead to internal leaking of fluids.  This will cause the excavator to lose tension and droop when un-powered.

The first source of contamination is usually created by, and is introduced into the hydraulic system during the manufacturing process.  Slag, metal filings, rubber crumbs, and other manufacturing waste and by-products can all enter the system during the manufacturing process.  These unwanted particles may vary in size from only 3 to 5 microns, but still pose problems for sensitive internal parts of the hydraulic system.  Obviously, the better the production process, the less debris that will enter the hydraulic system.  Less debris will help to reduce the negative impact on the clearances between moving friction parts.

Contaminants may also form during the course of the natural wear process of hydraulic system components.  Normally these contaminates will be removed by special filters, but once those filters become saturated they will require timely replacement.  If the filters are not replaced, contaminates will continue to circulate causing internal damage to your hydraulic system.  Besides visual inspections, many manufacturers now include special sensors that indicate filter contamination levels alerting the operators that it is time to replace the filters.

Oil and Fluid Replacement Intervals

Replacing operating liquids based on time, miles/kilometers, or hours was at one time the only real way to manage your equipment preventive maintenance program.  Replacement of fluids based on the operating time of the excavator is no longer necessary from an economic and labor cost viewpoint.   With time and distance based change intervals, the actual condition of the fluid was not taken into  consideration.

Today, Oil Sampling and Analysis Programs are far better at monitoring fluids and oils and telling us the proper time to replace or regenerate the oils rather than using time and distance only parameters.  Oil analysis, along with timely filter replacement will prevent the contaminates from circulating in your equipment’s hydraulic system.  Magnets placed on filters, drain plugs, and in fluid reservoirs can also reduce the amount of metal contaminates from circulating and causing damage in the hydraulic system.

Danger of Non-Organic Contaminates

Non-organic particles, such as quartz, feldspar, aluminum oxides, and iron pose the greatest amount of danger to the hydraulic drive system.  The main danger is that the hardness of these highly damaging particles is higher than that of the hydraulic system parts.

These harmful contaminants enter the gaps between the moving friction parts suspended in the fluid.  They disrupt the oil film and tear the surface of the components with their edges like a piece of course sandpaper.  The time it takes before wear becomes a problem depends on the amount of contamination in the fluid, but unless they are removed or prevented from entering the hydraulic system, they will cause damage.  If the size of the particles are between 5 and 45 microns, the pumping assemblies and the spool may further pulverize them causing accelerated component wear.  For instance, before operation, the correct radial gap in precision pairs of distribution valves is between 6 and 8 microns.  Due to contaminate based wear, the radial gap may grow to as much as between 32 and 46 microns reducing performance and causing long term damage problems.

Preventing Contamination from Entering Hydraulic Fluid Reservoirs

Contamination of oil also occurs when oil comes in contact with dusty air when the fluid is poured into the hydraulic tank or when transported in open containers.  Airborne dust may also enter the fluid through loose connections of hydraulic system pressure lines and hoses.

The question you may be asking is; Can dust, dirt, and water be excluded from entering the hydraulic system when it is filled?  The answer is yes.  Since oil is lighter than water, the water will settle below the oil.  If at all present, water and other settled contamination will be found at the bottom of the oil container holding the oil you want to introduce into the hydraulic equipment.  The oil may be put into the hydraulic tank by placing the end of a suction line into the oil container which effectively eliminates any mixing of oil and outside air.  The hose must not however, be lowered to the bottom of the container where it may transfer water, moisture, and other contaminates into your hydraulic equipment fluid reservoir.

Of course, the hydraulic system should not be filled with a bucket or other open containers, but with special filling equipment similar to the kind that is used at gas stations.

The best way to handle the transfer of oil is with the “refinery – oil truck – hydraulic tank.”  In order to prevent contaminants from entering the hydraulic equipment’s fluid reservoir however, the oil from the refinery should be clean.  It should also be passed through a “special 4 micron filter” as it is being pumped from the truck’s oil container into the equipment’s hydraulic fluid reservoir tank.

Importance of Monitoring Filter Service Life and Fluid Service Life

Engineers always look for ways to increase filtration fineness which in some cases may lead to filter clogging and buildup of back pressure tripping the safety valve.  When that happens, fluid will by-pass the filter and unfiltered fluid will be circulated through the hydraulic system.  Do not try solve this issue by increasing the safety valve pressure parameter.  It will only serve to increase the load on the hydraulic pump and could possibly result in premature pump failure.  The best solution is to replace filters on a timely basis and to employ the GlobeCore Process as part of your ongoing preventive maintenance program.  The GlobeCore Process eliminates contaminated oil and fluid problems before they cause damage to your valuable hydraulic system equipment.

Its time to get with the Process, The GlobeCore Process!

Oil Purification Equipment for Transformers

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The length of a transformer’s service life is determined by the service life of its insulation system.  If the insulation fails, the transformer fails.

Transformer insulation is made up of two components: (1) a liquid insulator known as transformer insulating oil; and (2) a solid insulator made up of Kraft paper and other cellulose material.  As much as 80% of a transformer’s insulation protection however, is provided by the insulating oil.  The insulating oil can be either changed, purified, or regenerated, but the solid insulation must last the entire service life of the transformer.  Transformer Preventive Maintenance therefore, is vitally important to the life of your transformer.

Industry statistics reveal that approximately 85% of  transformer failures are caused by insulation system malfunctions and failures.  Bad insulating oil will lead to degradation of the insulating paper and ultimately to catastrophic transformer failure.

Transformer oils are designed to maintain and increase the dielectric strength of the insulation material in the windings.  This is possible as a result of the permeation of oil into the solid insulation materials such as the paper, fabric, and cardboard that make up the solid insulation section of the transformer.

Due to its low viscosity, transformer oil is able to enter and flow through the solid insulation and also serves to dissipate excess heat by transferring the heat to the cooling system as it flows in and out of the solid insulation.

Degradation of transformer oil performance is caused by aging due in part to a process called oxidation.  This process occurs in transformer oil even in the most ideal of conditions.  As soon as oxygen and water enter the oil, the oxidation process begins and is unavoidable.  The insulating oil’s condition is also influenced by various solid particles known as particulate matter that enter into the transformer and become suspended in the oil.  Reactions between hydrocarbons, water and oxygen are significantly accelerated in higher temperatures which causes oil to decay or oxidize.  Oxidation cannot be stopped entirely, but it can be slowed significantly by oil treatment.

An annual oil check known as “Oil Analysis” is one the best tools for transformer preventive maintenance.  Special analysis of the oil will alert the operator to the condition of the oil and will tell him when to service the transformer.  Oil analysis can also indicate the overall health of the insulating paper.  A well organized oil analysis program provides the best way to monitor the acid number of the insulating oil and enable the operator to perform preventive maintenance before the contaminates in the oil become overly aggressive against the insulating paper.

A good preventive maintenance program should include purification and regeneration of transformer oil as opposed to merely changing the oil.  The main objective of preventive maintenance is the removal of oil aging products (contaminates) from the oil and the solid insulation before they cause damage to the insulation system.

When changing the transformer oil, it is usually replaced on site.  First, the transformer is dried, then its top part is rinsed by naphthenic or regenerated oil to remove dirt deposits. Only then the transformer is re-filled with new or restored oil.

The best and most cost effective way to service a transformer is with the GlobeCore Process.  Contaminated transformer oils are purified by the GlobeCore CMM-1A units.  The GlobeCore CMM-1A units are designed for the purification and drying of transformer oils.  The oil is dried by vacuum while the evaporating moisture is removed from the surface of the oil.  The oil’s viscosity should not exceed 70 cSt at 50ºС/122ºF.   GlobeCore’s CMM oil purification units offer purification of oil up to ISO4406 purity class 9.

Regeneration and purification of oil, using the GlobeCore Process, may be performed onsite and with the transformer energized or de-energized.  First the oil is pumped out and heated and then is passed through the GlobeCore unit.  The CMM unit degasses, filters and dries the oil and then returns the treated oil back into the transformer through the expansion tank.  The process is repeated until the composition of the oil meets industry standards.

Its time to get with the Process, The GlobeCore Process!

Transformer Oil Purification: Dewaxing

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Paraffin can be removed from transformer oil in several ways.  The most common methods are removal of solid crystals from the solution at low temperature and removal of n-paraffin hydrocarbons in combination with carbamide.

Dewaxing combines the treatment of oil with a special solvent (a mix of methyl ethyl cetone, benzene and toluene), heating the oil to 25-30 degrees (Celsius) higher than the oil’s cloud point (Wax Appearance Temperature or WAT), cooling to the required temperature and separation of solid hydrocarbons.

Acetone and methyl ethyl cetone solve some paraffin, but almost no oil.  Benzene is added to increase solvent capacity.

A mix of acetone (methyl ethyl cetone) with benzene can solve some paraffin and all liquid oil components at low temperatures.

An alternative way of dewaxing is the use of carbamide (urea) which forms a solid complex with paraffin.  The latter may be filtered and, after treatment with hot water, regenerate the carbamide. Filtered oil must also be treated with hot water to remove traces of urea.

The main advantage of carbamide dewaxing is that the whole process occurs at normal temperature and there is no need to purchase and install cooling systems.

Just like with any with other method however, this method also has its disadvantages.  The first disadvantage is the high melting temperature of isoparaffinic hydrocarbons that contain some methyl and ethyl groups.  Some naphthenic and aromatic hydrocarbons can melt at relatively low temperatures.

At the same time, carbamide treatment removes n-paraffin and isoparaffin hydrocarbons, but only if they contain one ethyl or methyl side chain.  Today the process is mostly used for the treatment of transformer oils made from acid-base oil refining.

The “Cold Dewaxing” process dominates the processing of transformer oils made by phenol purification of some crude oils.

Activated charcoal is different from silica gels, alumina gels and bleaching clays in the way that it can adsorb hydrocarbons with long chains.  It can adsorb just like solid paraffins of normal structure.  It has been suggested to utilize  activated charcoal for oil dewaxing, but this method has not been adopted by the industry or placed into widespread practice.

The main method of transformer oil distillate purification is adsorption.  It can also be the finishing operation in the final purification of oils produced by other methods.  Contact purification is also a possible method.

Oil Purification (Filtration)

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The main factor in determining the length of time to complete the purification process, is the degree or level of oil contamination.  The higher the “Acid Number” of the oil. the longer the process will take to complete.  In any case, the process should be controlled by special instruments.

Any new components installed into a hydraulic system must be just as clean or more clean as the ones already installed.  Component manufacturers are obligated to provide information on the purity of each component.  In case of hydraulic tank contamination, it must be cleaned during oil processing.  At the end of the process, the purity of oil will only be as clean as the cleanliness of the tank’s internal surfaces.  If hydraulic liquid is replaced by another, insoluble and not mixed with the original liquid, the time of purification increases drastically.

The Purification Process requires checking all filters and possibly replacing them as required.  The common misconception is that filters are a universal solution to maintain the cleanliness of oils and fluids.  Filters are not intended for the purification of heavily contaminated oil or fluids that may contain particles of metal, sand, small stones and other foreign objects.  Oil, water or air contaminated with such particles will remain contaminated after passing through the filters.  To ensure full system purification, it must be completely rinsed.  Oil and other fluids must be filtered thoroughly through an external filter.  This method however, has certain drawbacks, of which the most important one is the significant time required for external purification.  A good example of a long purification process is a large lifting machine which may take up to 15 hours to complete.

The only way to ensure the reliability and durability of hydraulic motors, pumps and other hydraulic components is efficient filtration (removal ) of solid particles and moisture from hydraulic fluid.  The existing national and international standards define the norms which the fluid must comply with. (16/14 class, ISO 4406)  Absolute filtration fineness is set at 3 microns.

Depending on the specific type of equipment, the purity requirements of the fluid may vary.  The versatility of purification and filtration systems therefore, becomes very important.  Versatile systems allow for operation with different types of fluids and ensure the required purity class regardless of original contamination.

This is just what GlobeCore offers. The GlobeCore UVR vacuum purification plants lighten and purify fluids, remove aromatics from turbine oil, industrial oil, and transformer oil as well as other petrochemical products, e.g. dark diesel fuel, HFO, gas condensate etc.

Improving Hydraulic Fluid Operation

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Hydraulic Fluids and Oils

The loss of performance by hydraulic fluid systems is a rather important problem because it leads to serious issues with turbine system performance and safety.  The loss of performance is normally caused by failures and damage in the regulation, lubrication and the sealing systems of the generator shafts.

The problem has become increasingly important because many power generation facilities are approaching the end of their service life and require increased attention and maintenance.  But, the current methods and devices for oil quality control, as well as oil purification equipment, are often obsolete and far from efficient further compounding the power company’s problems.

The International Standards Organization (ISO) recommends that reliable operation of turbine systems requires that the amounts of particulate matter in circulating turbine oils be kept to between 3 and 25 microns.  (See ISO 4406).  Anything larger can have adverse consequences on your turbine equipment.  These limitations are due to the fact that the distance between the support and the bearing pad with max load is 10 microns.  At start up, the lubricating layer of oil on the bearings is between 5-8 microns.

Most turbine regulation systems include spools and sleeves with radial clearances of between 50 to 100 microns.   If the spools rotate between them and the bearing box, the clearance should be set to between 10 to 25 microns.  The functioning of the turbine regulation system may be accompanied by failures due to solid contaminants that accumulate in the gaps in the regulation assemblies and spool clearances.  Serious damage may be caused by foreign particles entering the support bearing which may lead to a disruption of the pad setting.

If the turbine oil is contaminated by foreign substances and/or water, it will inevitably lead to over heating during operation and will cause premature failure of the bearings.  Such operation also makes the regulation system operation unstable and will cause additional unscheduled repair costs.

If the oil becomes contaminated and loses its ability to perform its intended purposes, it must be changed.  But, that will significantly increase your equipment operating and maintenance costs.  This can be avoided however, by performing timely scheduled preventive maintenance that includes purification of the hydraulic/turbine oil.  The GlobeCore Purification Process (GlobeCore Process) is designed to extend the service life of your hydraulic oils from 3-5 years to as much as 10 years.  Using The GlobeCore Process therefore, will lead to significant savings in long term maintenance costs.

Hydraulic System Filters

Some of the commonly used filtering elements used in hydraulic equipment are made from fabric, composite membranes, paper, polypropylene, zeolite, fuller’s earth, fiberglass, metal fibers, ceramics, products of powder metallurgy, ion exchange resins and metal meshes.  Each filtering media has both advantages and disadvantages.

Metal Mesh Filters

Considering the high degree of contamination that can be found in hydraulic fluids and oils used in modern equipment, the first filter choice seems to be to use metal mesh filters with between a 10 to 20 micron filtration fineness.  There is a catch however, even a 20 micron mesh filter can only capture particles of this size nominally.   That is because the orientation of particles in the liquid is random.  It should also be remembered that the beta ratio of filtration describing the retention capacity is from 10 to 100 times less than metal mesh filter’s advertised fineness.  Pump vibrations will also serve to further decrease the efficiency of metal mesh type filters.

To restore the functionality of a contaminated mesh filter, it will require rinsing and cleaning.  It is however, a complex process that requires an ultrasonic bath in detergent with heating and a very careful air purge process.  Even rinsing does not fully clear all contaminants from the mesh.  Thus, the life cycle of such elements is limited.

Another point to keep in mind is that the price of a mesh filter is approximately five times that of single-use filter element.

Fuller’s Earth Systems

Fuller’s Earth is not generally used for turbine oil purification since it can capture the inhibitor and salts from the oil causing “dieseling” of the oil.  Fuller’s Earth however, is widely used in transformer oil purification and regeneration.  Its main advantage being the ability to undergo multiple re-activations over hundreds of regeneration and purification cycles.

Centrifuges

Centrifuges are another means of oil purification, but they cannot remove particles smaller than 5 microns from the oil.  If the amount of the particulate matter is large enough, they can significantly degrade oil purity and cause equipment failures.

Electric Purification

For especially clean hydraulic fluids, electric purification is another possible choice.  This is a quickly developing modern method of fluid purification.  It has been tested extensively with oils stored in sealed vessels with excellent results.  There has been sufficient experience in using electric purification methods for petrochemical products and crude oil to gain wide acceptance in the fluid industry.

The process requires the preliminary heating of the liquid, but causes no resistance to the flow of the product and is simple to control.  The intensity of the process depends on applied voltage and the viscosity of the oil product.  The disadvantage of this method is that the equipment for this purification method cannot currently be installed on operating machines.  One of the issues with such systems is the need for protection against electric breakdown.  Another factor is the reduction of the oil’s “interfacial tension” after electric purification process.

There is therefore, no single systematic approach to purification of industrial oils.

Combined Approach

Problems with hydraulic oils and fluids can first arise at the stage of purity control.   Since all facilities are not fully supplied with reagents and the proper required equipment, oils and fluids may not be free from moisture and other forms of contamination at the point manufacture and delivery.

Years if industry experience shows that high quality oil purification requires a combined approach that includes the following:

1. Formation of an independent group of experts and service personnel for the control of oil purity in turbines and hydraulic systems.

2.  Creation of separate of “Chemical Control Departments” at nuclear, hydro and thermal power generating plants.  They will run oil analysis labs and and provide digital moisture meters for oil monitoring.  These departments with be responsible for scheduling and performing preventive and scheduled maintenance.

3.  The best solution for your oil purification problems would include purification by GlobeCore’s UVR oil purification equipment.

4.  Maintenance departments at power generation companies should be equipped with modern service equipment (such as the GlobeCore  UVR purification units) and the personnel should be adequately trained for the use of such equipment.

The GlobeCore Process is most efficient and cost effective oil purification process in the world today!

It’s time to get with the Process.  The GlobeCore Process!