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Contamination in Hydraulic Systems: Causes, Effects, Prevention, and Remediation

Contamination in hydraulic systems poses a significant threat to the reliability, performance, and lifespan of hydraulic equipment and accounts for 80% of system breakdowns primarily resulting from contamination. From microscopic particles to water and air, various contaminants can infiltrate hydraulic systems, leading to a range of issues such as component wear, fluid degradation, and system failures. In this comprehensive blog, we'll delve into the causes of contamination, its effects on hydraulic systems, preventive measures, and remediation techniques to ensure optimal system operation.


Understanding Contamination in Hydraulic Systems:

Causes of Contamination: Contamination in hydraulic systems can originate from various sources, including:

  • External contaminants: Dust, dirt, debris, and environmental pollutants can enter hydraulic systems through breather vents, cylinder rod seals, reservoir openings, and other access points.
  • Internal sources: Internal components such as hoses, seals, pumps, and valves can degrade over time, releasing particles, metal shavings, and debris into the hydraulic fluid.
  • Water and moisture: Water ingress from external sources or internal condensation can lead to fluid degradation, corrosion, and microbial growth within hydraulic systems.
  • Air entrainment: Air bubbles or foaming in the hydraulic fluid can introduce air entrainment, leading to reduced lubrication, cavitation, and performance degradation.


Effects of Contamination: Contamination can have numerous adverse effects on hydraulic systems, including:

  • Component wear: Abrasive particles and debris can cause premature wear and damage to hydraulic pumps, valves, cylinders, and other components, leading to reduced efficiency and reliability.
  • Fluid degradation: Contaminants can accelerate fluid degradation, leading to oxidation, viscosity changes, additive depletion, and reduced lubricating properties, compromising system performance and longevity.
  • Increased maintenance: Contamination-related issues necessitate frequent maintenance, filter replacements, fluid changes, and system flushes, resulting in increased downtime, labor costs, and operational disruptions.
  • System failures: Severe contamination can lead to catastrophic system failures, hydraulic fluid leaks, component malfunctions, and safety hazards, posing risks to personnel and equipment.


Types of Contaminants: Contaminants in hydraulic systems can be classified into various categories, including:

  • Solid particles: Particulate contaminants such as dust, dirt, metal shavings, and wear debris are the most common type of contamination in hydraulic systems, causing abrasive wear and damage to components.
  • Water and moisture: Water ingress, condensation, or emulsified water in hydraulic fluid can lead to corrosion, rust, oxidation, and microbial growth, compromising fluid integrity and system performance.
  • Air entrainment: Air bubbles or foaming in hydraulic fluid can lead to cavitation, reduced lubrication, increased noise, and reduced system efficiency.
  • Chemical contaminants: Chemicals, solvents, and contaminants from hydraulic fluid additives, system materials, or external sources can degrade fluid properties, causing fluid breakdown, corrosion, and seal degradation.


Preventive Measures for Contamination Control: To mitigate the risk of contamination and preserve hydraulic system integrity, consider implementing the following preventive measures:


  1. Filtration: Install high-quality filters, strainers, and breathers in hydraulic systems to remove solid particles, water, and air contaminants from the fluid, ensuring clean and contaminant-free operation.
  2. Proper fluid storage and handling: Store hydraulic fluid in clean, sealed containers, and handle it with care to prevent contamination from airborne particles, moisture, and external contaminants during storage, transportation, and handling.
  3. Regular maintenance: Implement regular inspection, maintenance, and fluid analysis programs to monitor system condition, detect contamination issues, and address them promptly through filter changes, fluid flushes, and component replacements.
  4. Component selection: Choose hydraulic components, seals, hoses, and materials that are compatible with the hydraulic fluid and resistant to degradation, minimizing the risk of contamination from internal sources.
  5. Fluid cleanliness standards: Adhere to industry cleanliness standards such as ISO 4406 for hydraulic fluid cleanliness levels, ensuring that hydraulic fluid meets specified cleanliness requirements to prevent contamination-related issues.


Remediation Techniques for Contamination Control: In cases where contamination has already occurred, consider the following remediation techniques to restore hydraulic system integrity:


  1. Fluid flushing and filtration: Perform fluid flushing and filtration processes using high-efficiency filtration systems and flushing fluids to remove contaminants, sludge, and degraded fluid from the system, restoring fluid cleanliness and performance.
  2. Component cleaning and replacement: Clean, inspect, and replace contaminated hydraulic components, seals, filters, and hoses as necessary to eliminate sources of contamination and restore system functionality.
  3. Water removal: Implement water removal techniques such as coalescers, centrifuges, and water-absorbing filters to remove water and moisture from hydraulic fluid, preventing corrosion, fluid degradation, and microbial growth.
  4. Air removal: Use air removal devices such as vacuum dehydrators, air eliminators, and air release valves to remove air entrainment and foam from hydraulic fluid, restoring proper lubrication and system performance.
  5. Fluid analysis and monitoring: Conduct regular fluid analysis and monitoring to assess fluid condition, identify contamination issues, and track system cleanliness levels, enabling proactive maintenance and contamination control measures.


Contamination poses a significant threat to the reliability, performance, and lifespan of hydraulic systems. By understanding the causes, effects, preventive measures, and remediation techniques for contamination control, engineers can ensure clean, reliable, and efficient operation of hydraulic equipment. Through proactive maintenance, filtration, fluid analysis, and proper handling practices, hydraulic systems can maintain optimal performance and longevity, minimizing downtime, maintenance costs, and risks of system failures associated with contamination-related issues.


For help with all your hydraulic requirements, please contact Neilson Hydraulics on 01709 821 002, email: sales@neilson-hydraulics.co.uk or visit: https://www.neilson-hydraulics.co.uk/