When conducting a class on hydraulic and lube oil systems, I often find that the students are surprised by how much fluid condition affects system operation and the numerous mechanical problems that derive from the oils not performing at 100% of design characteristics. The single greatest cause of oil not performing as it should is fluid contamination. Contamination is a real world problem that—if not prevented or controlled—can cause the system to work much less efficiently or even cause catastrophic failure.

The American National Standard Glossary of Terms for Fluid Power defines contamination as “Any material or substance which is unwanted or adversely affects the fluid power system or components or both.”

Sources of contamination:

• It can be generated in the system from normal operation, oftentimes during system design and selection or location of filters.
• It can come from ingressed contamination, resulting from faulty system components.
• Induced contamination also stems from system component manufacturing processes or inattention to detail when handling, storing and transporting system components and the hydraulic and lube oils themselves.
• The new oil itself (this is what shocks the students the most). Just because the oil is new does not mean it is clean. It can encounter contaminants if oil barrels are not sealed or stored properly, as well as when being poured into a system for the first time. If a reservoir opening is not clean, dirt may flow in with the new oil.

Failure by contamination
Now that we have discussed possible causes of contamination, lets discuss the two basic types of failures that are a result of contamination:

Degradation Failures — These include sluggish system operations, loss of system accuracy and system speed, overheating of the system, and inability to build full system pressures. These are usually not detected until damage is irreversible. To prevent degradation failure, adequate filtration must be provided and maintained for the system.

Catastrophic Failure — Contamination is not always the cause for catastrophic failure, but contamination is the most possible cause. Large particulate contaminates cause restriction of moving parts, which in turn can cause parts to stick or jam. Large particulate contamination clogs passages used for the lubrication of moving parts. Without proper lubrication, immediate failure can occur.

Considering the fact that contaminants can cause poor system operation, component failure and system failure, we must take positive steps to prevent the introduction of contamination in our hydraulic and or lube oil systems.

The first step in reducing contamination in a closed system is to pay attention to detail when transporting, handling, storing, and replenishing our systems. Analyzing fluids before they are introduced to systems and keeping the outside of barrels and reservoirs clean can go a long way in reducing fluid contamination. Finally, proper filtration is key to keeping systems contaminant-free.