From the book: Fluid Contamination Control

Knowing the potential and probable sources of contaminant helps to establish an effective exclusion program. In reality, three fundamental modes contribute to contamination:

Injected by people - implanted during manufacturing or induced in the field during maintenance, repair or overhaul operations.

Generated by the system - created tribologically, chemically or by desorption.

Ingested by the machine - introduced by inhalation of dust, air and water; encroachment of energy; and migration of microbes from the environment.

More about Fluid Contamination Control

Water contamination in hydraulic systems can devastate an organization’s reliability objectives. Fortunately, with a diligent effort, water contamination can be effectively controlled by setting goal-based target dryness levels, achieving the targets through effective exclusion and removal of water and periodic monitoring to ensure that target levels are maintained. The critical first step is to establish target levels that reflect the organization’s reliability goals and take into account the mechanical sensitivity of the hydraulic system in question.

Rust and corrosion are the most obvious effects of water contamination. However, water also lies at the root of vaporous cavitation, hydrogen-induced embrittlement and blistering and fatigue wear in rolling contacts. Read the entire story.

There are several suppliers of special adsorbents that can be used to get acids out of used oil. These powder-like materials, sold in bulk or cartridges, have the ability to selectively strip acids from partially oxidized oils. For instance, a used turbine oil with an acid number of 0.6 can be brought back to a level below 0.1 (near the original, new-oil level) using these materials.

Commonly used adsorbents include fuller's earth and activated alumina; ion exchange resins can also be used for this purpose. There are certain risks and disadvantages to reclaiming used oil in this way, including possible depletion of certain additives and the migrating of minerals from the adsorbent into the oil.

External level gauges provide a visual check of hydraulic reservoir oil level without lifting an access lid/cover and exposing the fluid to airborne debris. These sight glasses should be marked to correct oil fill range for both hot and cold system conditions.