Oil Contamination Destroys Hydraulic Systems #OilChat 67

Hydraulic oil is the lifeblood of all hydraulic systems. It is therefore of utmost importance to use the correct hydraulic fluid. Equally important is the cleanliness of the fluid, particularly in mobile hydraulic systems such as those fitted to earthmoving and agricultural equipment. Ensuring hydraulic system cleanliness and contaminant-free fluids is essential to prevent damage and increase the life span of hydraulic systems. The wrong oil and contamination are the biggest enemies of hydraulic systems and are the cause of most hydraulic system failures. Even the smallest of particles can wreak havoc on hydraulic system components like seals and servo valves. Before we discuss how lubricants become contaminated with dirt particles, let us get familiar with the different types of failure that can occur if you fail to keep contaminants out.

Degradation Failure symptoms are sluggish operations, loss of system accuracy and speed, overheating and inability to build up full pressure. Essentially the system is not running as it was designed to do. Degradation failures often go undetected until damage is irreversible. To prevent degradation failure, adequate filtration for the system must be installed and maintained.

Transient Failure is caused by particles that briefly interfere with the function of a component. Often, this type of failure happens sporadically and goes unnoticed, although the consequences will become obvious with time. The particles lodge in critical clearances between matching parts, only to be washed away during the next operation cycle. As a result, components become less predictable and therefore unreliable.

Catastrophic Failure will sneak up on you with no warning and is irreversible in nature. Though not always the cause of catastrophic failure, lubricant contamination is often the culprit.  Large particles restrict moving parts and clog the very tight passageways found in a hydraulic system. Once these passageways become clogged, the system will not be able to operate.


Contamination can find its way into the oil in a variety of ways, which is why a comprehensive contamination control program is a must. The most common sources of contamination are:

Built-In Contamination: This type of contamination is especially difficult to avoid as it is the result of the manufacturing and assembling of the equipment. These particles include casting sand, machining debris, weld spatters, paint and pipe sealers, to name a few. To avoid the harmful effects of built-in contamination, flush system and components prior to assembly.

Ingressed Contamination: Mobile hydraulic systems are constantly being infiltrated with contaminants, especially in agricultural, construction and mining machinery. This is where selecting the correct filtration system for your application is particularly important.

Generated Contamination: Hard particles in the oil tend to generate wear particles. This phenomenon is known as three-body abrasion and occurs when particles between two surfaces scrape material off one or both surfaces. Other processes like rust, cavitation, corrosion, erosion, fatigue, and metallic contact between moving parts can also generate particles and add to the contamination that is already present in the system. Although these issues are not always avoidable, their impact can be reduced by proper filtration.

To ensure reliable mobile hydraulic system performance, it is important to do regular maintenance services, use a suitable filtration system, introduce an oil analysis program if possible at all and, last but not least, use the correct hydraulic fluid. To find out which hydraulic oil is best for your application phone 011 462 1829, email us at info@bcl.co.za or visit www.bcl.q8oils.co.za