Contamination

The useful life, performance and reliability of a hydraulic system can be directly related to the contamination level of the fluid. Understanding where contamination comes from is a major step towards getting the most from your hydraulic system.

What enables contamination?

Opening the breather cap to add oil or to check the fluid level.

Contaminants are frequently found in newly assembled hoses, valves, pumps, pipes, motors and components in general. This is especially true when the parts are new or the components are started up for the first time.

Carelessness during system assembly can cause big problems... so be diligent in keeping everything clean. Use shop air to blow dirt and particles off components awaiting assembly.

After the system is in use, dirt and water may leak in through the breather caps. Water may also be found in the form of condensation.

Worn cylinder seals will be indicated by leaking oil and dirt accumulation.

Improperly filtered single-acting cylinders.

How to Avoid Contamination

Installing a new hydraulic system?
Flush all lines before adding fluid, and blow dry with shop air to remove excess flushing fluids. Leave plugs in components until you are ready to make connections.
On tapered pipe threads use a good hydraulic sealant such as Locktite 56931. Do not use teflon tape as this allows over tightening by wedging, and cracks may develop in the female component necessitating replacement.

Replacing a worn or defective pump or motor?
5 to 10 gallons of oil in system: replace with new oil, drain and flush the entire system.

More than 15 gallons of oil in system: You Should probably consider cleaning the hydraulic fluid and return it to service. This will not only help your pocketbook, but the environment as well. Call your local hydraulic shop and ask how this is done.

Oil that has been in service for many years may have lost some of the additives needed, and may not be worth salvaging. The same is true of fluids that run at extreme temperatures.

Filters and/or cartridges are cheap, so replace them as needed. Be sure to clean the suction screen. Also, in extremely dusty conditions, you may want to replace the old-style breather cap with a spin-on oil filter turned upside-down. The filter adapter has male threads at both ends so that dirt falls off, not in, when the filter is changed.

For more information on contamination and filtration go to A Simple Study in Filtration

Need to replace your filters? Check out our selection on our filters page.