Bubble, Bubble, Oil and Trouble: How Contaminated Fluid Could Be Causing Leaks in Your Hydraulic System

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Hydraulic cylinder systems have countless uses, but whatever you use your hydraulic system for, it needs a ready supply of clean, uncontaminated hydraulic fluid. Contaminated oil can lead to chronic leaking of your hydraulic system if the issue is neglected. It can also contribute to other serious problems, such as cylinder drift and cavitation. Needless to say, keeping your hydraulic fluid clean is vital for an efficient hydraulic system.

What kind of contaminants can enter the fluid of a hydraulic system?

The word 'contaminants' may conjure images of noxious fluids seeping in your hydraulic system's fluid supply, but a variety of otherwise-benign substances can become big problems if allowed into the fluid of a hydraulic system. Some of the most commonly encountered contaminants in hydraulic fluid include:

• Air: Air can be sucked in through leaking hoses, failed seals and O-rings. Once inside your fluid supply, it creates bubbles that can dramatically increase the friction and running heat your hydraulic system creates, leading to increased wear and a higher chance of malfunction.
• Water: Since hydraulic fluids are generally oil-based, they do not mix with water drawn into the system through leaks and standing water puddles. This creates pockets of water inside your system that act as focal points for heat accumulation, increasing the rate of wear and altering the internal pressures of working cylinders.
• Dirt and detritus: Dirt, grit and other particulate matter can enter a hydraulic system via a number of potential entrances and is a common cause of leaks as it abrades the interior surfaces of your hydraulic system. It can also collect in your fluid reservoirs, undermining overall fluid capacity.
• Perished fluid: Even the fluid itself can become a contaminant if used and abused for too long, as aging hydraulic fluids will eventually separate and lose their lubricating and heat conducting properties.

How can I prevent these contaminants from entering my hydraulic system?

As you can imagine, keeping these various nasty substances well away from our hydraulic fluid supply is highly desirable. Following these key guidelines should help keep your fluids as clean and uncontaminated as possible:

• Check for leaks frequently: Hydraulic systems are virtually sealed off from the outside world by virtue of their designs, so contaminants will generally enter a system through a hole that shouldn't be there in the first place. Have your system professionally inspected for leaks frequently, paying particular attention to flexible hoses which can crack and seep after long periods of use. 
• Choose the right fluids: Hydraulic fluids are generally formulated to suit a particular task over others, so you should choose a fluid suited to the needs of your particular hydraulic system (choosing fluids manufactured by the maker of your hydraulic system is generally a good way to ensure compatibility). Unsuitable oils can contain unnecessary additives that may have deleterious effects on your system, causing problems with pressure and heat exchange.
• Change fluids frequently: Whatever type of hydraulic fluid you opt for, it should be changed regularly to prevent perishing, and to flush out and contaminants that may have entered the system during the last fluid change. Dark, burnt-smelling fluid should be changed as soon as possible.
• Keep wipers well maintained: The wipers are the small brushes that clean the rods of your hydraulic pistons as they exit their corresponding cylinders. They are essential for preventing solid contaminants from entering your hydraulic cylinders as they function, and should therefore be kept in good condition and replaced frequently.

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4 April 2017