Hydraproducts Blog

Get in touch to talk to us today about your requirements

14Nov

Bleeding Air from a Hydraulic System

Although manufacturers may state that bleeding air from a hydraulic system is not necessary, many engineers prefer to perform this maintenance action.

Broadly speaking, over time air will usually find its own way out of a hydraulic system. Even air that has become trapped in oil will usually get transported back to the reservoir at some point.

However, bleeding air from a hydraulic system can speed up this process. It’s common knowledge that air trapped in a system can cause mechanical damage and lead to erratic operation.

For example, air contamination damage may include:

  • Erosion caused by air bubbles in oil collapsing under pressure
  • Decrease and sometimes loss of lubricity that goes on to cause scoring, abrasion and other friction damage between surfaces that should be lubricated
  • Compression leading to ignition of the mixture of air and oil in the system, burning seals and damaging the cylinder.

Why would manufacturers tell any of us that bleeding or purging of oil is not necessary? Our thoughts are that if there is damage caused, then they can sell you replacement parts as they won’t be under warranty. However, there is also a chance that you could get injured as you bleed the air from the system if they condone it as a general practice and for this you could sue them for hundreds of thousands of pounds. In short, they are protecting themselves. Basically, it brings about a liability issue. They have a point: It’s not a beginner’s job to bleed the air from a hydraulic system and you truly do need to know what you’re doing to take this on.

A less dangerous but somewhat effective approach is to minimise any air on start-up. You can do this by filling any voids as you start up. For example, if you were to replace the cylinder, then you would fill it with clean hydraulic oil before you connect it. The same goes with other components such as the pump, intake lines etc.

Although it’s not possible to completely fill every component, it does offer a safe way to help to expunge any air in the system and that is helpful. 

Related

Do I need a Hydraulic Cooler for my power pack?

Do I need a Hydraulic Cooler for my powerpack?A design decision to fit a hydraulic oil cooler like t...

Read More >

Hydraulic System: More about Cavitation and Aeration

Hydraulic Cavitation and Aeration Although aeration and cavitation are very similar, they are cause...

Read More >

Why hydraulic fluid compatibility is so important

Ensuring you use the correct fluid for your hydraulic system is crucial right from the start, but wh...

Read More >

The Evolution of Hydraulic Power

Hydraulics has been around for a very long time. But are you aware of how far it has actually come? ...

Read More >

3 Serious Issues Resulting From Hot-Running Hydraulic Systems

If you’ve been following our hydraulic systems blog for some time, you’ll already know that heat c...

Read More >

What You Need to Know About Subsea Hydraulic Design

There are many factors involved in how much subsea hydraulic related applications are able to grow a...

Read More >
  • Back to top