HYDRAULICS Hydraulic power remains integral to many parts of the UK industrial economy. From metal processing and component testing to rail maintenance and waste management, most sectors rely on hydraulic actuation in some form. These systems are built for strength, yet their reliability often hinges on an invisible variable: the cleanliness of the fluid circulating inside them. As machinery becomes more precise and maintenance budgets face closer scrutiny, contamination control is moving from a secondary maintenance concern to a central measure of system health. Clean hydraulic oil is not just a matter of appearance. It determines how effectively pumps, valves, and actuators perform under load, and how long they last before repair or replacement. In practice, maintaining cleanliness is difficult. Systems breathe, seals degrade, and temperature changes draw in moisture. Microscopic debris from component wear recirculates until removed. Once particle levels rise beyond recommended limits, wear accelerates and efficiency drops. Over time, small contamination issues become the root cause of breakdowns that appear mechanical in nature. Across UK industry, the demand for finer control and higher energy efficiency is making this issue harder to ignore. Modern proportional valves and servo systems operate with extremely close clearances, meaning the size of an acceptable contaminant is smaller than a human hair by several orders of magnitude. Hydraulic components that would have tolerated moderate contamination twenty years ago now fail quickly under the same conditions. At the same time, energy costs are pushing operators to maintain fluids at optimum viscosity and cleanliness, reducing losses caused by friction and internal leakage. The conversation around filtration has matured in response. Most engineers now recognise that the choice of filter is only part of the solution. What matters equally is where filtration occurs, how it is monitored, and whether the results are verified through fluid analysis. Typical cleanliness targets, expressed using the ISO 4406 code, are between 18/16/13 for standard industrial systems and 15/13/10 for more sensitive ones. Achieving and maintaining these levels consistently requires careful sizing of filters, correct flow paths, and regular checking of pressure differential across elements to prevent bypass. UK suppliers and service companies are adapting to this change. Instead of focusing purely on hardware, many now provide system assessments and cleanliness management programmes. These include return-line filtration upgrades, dedicated offline “kidney loop” systems, and moisture control devices designed for the country’s variable climate. Condensation and airborne moisture remain persistent issues in outdoor or unheated environments, particularly in construction and materials handling. Water contamination accelerates oxidation, corrodes internal surfaces, and breaks down fluid additives, so desiccant breathers and waterabsorbing filters are becoming routine features in many installations. Air ingress is another growing concern. Entrained air changes the compressibility of the fluid and can cause erratic actuator 22 HYDRAULICS & PNEUMATICS November/December 2025 www.hpmag.co.uk Why fluid cleanliness is defining hydraulic reliability As operating margins tighten and expectations of reliability increase, managing fluid cleanliness has become one of the most practical ways to reduce failure risk and extend equipment life. H&P reports. movement or cavitation. The combined effect of air, water, and particulate contamination can be subtle but is cumulative. Addressing them requires a consistent approach rather than reactive maintenance when problems appear. Fluid analysis complements this approach. While filters manage contamination, analysis verifies that they are working and highlights issues before they affect performance. Periodic sampling, typically every few hundred operating hours, provides information on particle counts, moisture content, viscosity, and chemical degradation. UK laboratories now offer rapid analysis services, often including trend graphs that show whether contamination is stable, increasing, or declining. Maintenance teams can then schedule filter changes or system inspections based on actual condition rather than fixed intervals. This shift to data-driven maintenance is particularly valuable where machinery operates continuously or is difficult to access. Integrating filtration and analysis For operators, the practical challenge is integrating filtration and analysis into daily routines. Both depend on disciplined
RkJQdWJsaXNoZXIy MjQ0NzM=