Common Sources of Hydraulic Fluid Contamination
Contamination from the workplace. This includes solids, fluids, gasses and light (which can cause acids to form).
Common sources include foul air, metal scrapings from machinery, water seepage from heating or cooling, dust, welding spatters, etc.
Contaminants produced in the hydraulic circuit. Hydraulic circuits are a closed-circuit system of tanks, pumps,
flow control valves, pressure gauges, actuators, etc. The sliding actions within these systems produce friction which eventually cause
small bits of metal to wear off and enter the system causing abrasion. Eventually, the abraded surfaces allow oil to leak, causing
pressure loss and malfunction.
Contamination from oil fin cracks. Oil fin coolers often experience cracks which can allow water to permeate hydraulic
fluid, causing the fluid to emulsify. These emulsified fluids are often responsible for rust and cavitation within a system.
Contaminants from the decomposition of hydraulic fluid. The basic composition of hydraulic fluid is a hydrocarbon compound
combined with small amounts of oxygen. When this fluid comes in contact with high temperatures or continuous light, oxygen absorption is increased
and oxidation is accelerated causing a sludge deposition. At low temperatures, this deposition is often in the form of a gel-like sludge that can stick
to control valves and cause oil blockages. At higher temperatures, the sludge usually dissolves into oil contaminants.
Contamination from additives. Field studies have shown that some additives (added as anti-wear, antioxidant or abrasion preventatives),
hydrolyze and deteriorate at high temperatures, and can actually shorten the longevity of the fluid.
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