Off-line filtration, often referred to as a kidney loop, draws fluid from a reservoir, pumps it through a filter, and returns the clean fluid back to the reservoir. This fluid cleaning process can occur continuously or whenever fluid contamination exceeds a predetermined threshold. To further enhance the cost effective benefits of mobile filtration, this process can be performed when equipment is running or idle, so the hydraulic system does not to be shut down to change dirty filters. The filters will operate at maximum efficiency because fluid is pumped through them at a constant flow rate, rather than at a wide range of flows present in the hydraulic system.

Because it is so effective at removing large amounts of contaminants from a hydraulic system, many consider it to be the most cost effective method of filtration. The benefits of mobile filtration can be enhanced by sharing an off-line system among multiple hydraulic systems. This is easily accomplished with a filtration cart — essentially a portable, self-contained off-line filtration system complete with fluid lines, quick-acting couplings, filters, and motor.

The newest filter carts provide a convenient and effective method of off-line filtration, flushing, and fluid transfer for in-plant machinery and hydraulic equipment. These filter carts also include two in-series pressure filters that remove solid contaminants. In addition, a water-absorbing element may be installed to further remove particulate matter and water. Industrial manufacturers will see the immediate benefits of this hydraulic filtration solution in a variety of applications, such as:

• Filtering new fluids that usually fall above the recommended ISO cleanliness levels
• Supplementing existing filtration
• Transferring fluids from a drum or other storage container to a machine's reservoir
• Removing free water from previously filtered fluid
• Thoroughly flushing machines after service, repair, or rebuild, and Eliminating debris and dirt accumulated during fabrication, storage, and transport of new systems