Bulk Fuller's Earth Systems

Model BA-CL

Baron BA-CL series bulk filtration systems are designed for the regeneration of transformer oil by Fuller's Earth Filtration. Benefits to the oil include: acidity reduction, color improvement and sludge reduction.

Is Fuller's Earth Needed? 

For Class III oils that are service aged, fuller earth treatment will be required. Color number, Neutralization Number and Interfacial Tension are good indicators for Class III oils. Available in a variety of configurations sized to the flow rate of the vacuum oil purifier. They can be incorporated into the purifier system itself or provided as a separate module to be connected and used only when needed. 

Product Description

The BA-HV family of fuller's earth systems comes in a variety of sizes and types. They are available for in-plant stationary applications as well as mobile systems. They come available as stand-alone systems, as modules for integration into existing equipment or as integral parts of Baron vacuum oil purification systems.

Single bulk filter systems are available with earth capacities of 250, 500, 850, 1000 and 2000 pounds. Typically two or more filters of identical capacity will comprise a system. This allows optimum usage of the clay and change-out of the charge in one filter while the other is still in use.

Floor models are available for transformer manufacturing and repair facilities. Portable systems are available on open trailers, tarp-sided trailers, swing-door trailers, hard-sided hitch/tag trailers and semi-trailers.

Each clay filter is rigidly mounted in a frame that allows for dumping of the spent clay. A vacuum fill port is provided for connection to an external vacuum source for filling (a locally mounted vacuum system is available as an option).

Pressure gauges are provided on both inlet and outlet lines to the filter and a flow-sight indicator is provided to monitor flow conditions and purified oil color. In addition, a sight-glass is provided on the filter to visually monitor the condition of the clay. Whenever the vessel is filled with fresh clay, the filter is subjected to vacuum to evacuate all trapped air prior to flooding with oil.

The most efficient use of the clay is obtained by running the towers in parallel with the lead tower as the roughing filter and the second tower performing the polishing. When the clay in the lead filter is spent, it is changed and the series flow reversed to make the freshly charged tower the polishing unit and the former polishing unit the roughing filter.

Fuller's Earth

Fuller's earth can be used to decolorize and neutralize any petroleum oil, especially electrical insulating oils. It excels in neutralizing traces of strong inorganic acid. Due to the relatively large pores in fuller's earth, it is well adapted to the removal of high molecular weight sulfonates, resins and asphaltines.

Transformer oil will discolor as oxidation of the oil takes place. Color, by itself, is not a reliable test in evaluating the condition of the oil for further use. It is a strong indication that something is happening within the transformer that requires investigation. Once transformer oil changes from the yellow color range into the orange and red color range, it has degraded to the point where the vital parts of the transformer are being seriously affected.

As the color of the oil changes, sludge is forming in solution with the oil due to oxidation. This causes a drop in interfacial tension and an increase in the acid (neutralization) number. When transformer oil deteriorates to the red color ranges, deposited sludge continues to oxidize and harden, blocking vents and insulating cooling fins, causing higher operating temperatures. Insulation shrinkage may take place, and premature failure is possible.


Fuller's earth can be purchased in bulk or in 50-pound vapor-insulated bags. Each Baron bulk filter holds an even number of bags of 30/60 mesh, grade LVM bulk clay having a density of 28-36 lb/cubic foot and a specific gravity of approximately 2.45.

Care must be taken not to expose the fuller's earth to humid air or moisture. This causes the clay to loosen its granular structure and can turn it to plain mud. It is recommended that the clay be purchased in vapor-insulated bags to keep it dry. For best performance and flow rate, oil should be supplied to the filters at a temperature of 160-180 degrees F and a supply pressure capability of up to 80 psig.

Standard Features

  • Using ASME design housings, each system is equipped with an air release valve, drain valve, viewport, swing-bolt release bottom dumping cover and dovetail groove o-ring seal.
  • Welded fittings, installed by certified welders, are used wherever possible. This minimizes oil leakage potential, which is especially important on portable equipment.
  • Most systems are equipped with a vacuum filling system that allows the operator to draw clay into the filters using a hose. Man-handling bags to the top of the filters and pouring is not required. Vacuum filling also allows removal of air prior to oil introduction to minimize channeling of oil through the clay bed.
  • Most systems come equipped with a hydraulic dumping system that allows spent clay to be dumped into a hopper without shoveling or manual handling. Portable systems typically have hydraulics to allow the operator to tilt the filter clear of the rear of the trailer and then to power open the filter for automatic dumping.

Optional Features:

  • A variety of choices for making the system portable, including fully trailerized systems, benches, steps, storage boxes, hose storage tubes and others
  • Hydraulic, pneumatic, electric or manual winch-operated dump
  • Hydraulic tilting of filter for dumping. This option is useful when the filter must be installed in an area with low height clearance as the overall filter height is minimized.
  • Vacuum filling pump. This option is useful when an external vacuum source is unavailable or it is otherwise desired to have a dedicated vacuum source. The pump comes with a local starter, exhaust filter and dust trap.

What can we do for you?

Baron USA specializes in providing customized support, training, products and solutions to meet your specific needs. To learn how Baron USA can help you, call 93I.528.8476 or email us

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