Tag Archives: equipment for oil filtration

Buying and Storing Transformer Oil

Purchasing transformer oil is an important financial decision for your company.  It should be done very responsibly.

First, the buyer must a choose a brand of oil.  This requires careful consideration based on the type of equipment being used and the operating conditions the oil and the oil’s abilty to meet those conditions.

Second, the cost of the oil must be considered.  A small price difference in the cost of just one liter small can turn into a significant amount of money when purchasing a large volume of oil.

There are no universal recommendations for buying transformer oil. There are however, online services allowing buyers to compare transformer oil prices from various suppliers.  It is up to the buyer to research and choose a reliable wholesale distributor or retailer.

If you have already purchased transformer oil that meets the correct specifications and quality standards, then it is time to think about oil storage.

The practical way to store the oil is to use clean and dry, steel air tight vessels.  The tanks are usually coated with an oil resistant material inside.  The outside of the tanks should have anticorrosion and light reflecting coating.  The acceptable range of temperatures for storage of transformer oil is -40ºС to +60ºС/-40ºF to +140ºF.

The vessels should be equipped with valves for filling and draining as well as a manhole for cleaning, inspection and repairs.  Breathing systems must be equipped with silica gel or zeolite cartridges that can be monitored by special monitoring devices.

Three days after putting the oil into a storage tank, samples are normally taken for laboratory analysis.  Transformer oil in storage should be tested at least once a year for the following parameters:

  •  flashpoint;
  • dielectric strength at 90ºC/194ºF;
  • water extract reaction;
  • acid neutralization number;
  • particulate matter content in mircons; and
  • free water and moisture content.

It is also recommended to test the dissipation factor at 90ºС/194ºF at least once a year.

Each time the oil is tested for quality and purity, the results must comply with the parameters of fresh transformer oil regardless of the length of storage. Otherwise, the oil must be purified and regenerated to restore the oil to its new and clean condition.

GlobeCore offers a line of oil purification units under the CMM classification. These units improve color, remove acids, bases, and other aging products from any turbine, dielectric insulating oil, and industrial oils.

One of the advantages of the GlobeCore CMM line of units is their ability to regenerate oil on an energized transformer.  Another important advantage is the ability to reactive the fuller’s earth sorbent inside the unit many times over, reducing downtime for sorbent replacement and replenishment.

After the processing of transformer oil with GlobeCore equipment, transformer insulating oil is restored to an as good as new condition.

Purchasing a GlobeCore CMM unit gives you a modern efficient machine that is easy to operate and service.  The use of GlobeCore equipment and GlobeCore Process will extend the service life of the oil and the transformer significantly.

Oil filtration

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.

Oil Purification (Filtration)

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.