Air can become trapped in a hydraulic system from time to time and it is a common cause of poor performance, erratic operation, damage to system components and loss of power.
It is always recommended that you hire a professional hydraulic engineer to do any maintenance on new hydraulic cylinders in your system as anyone who does not know what they are doing runs the risk of further damaging the system or of causing injury to themselves or others.
Gather the Necessary Tools and Materials
If the cause of all the air trapped in the system is due to leaky hoses then you will want to have your replacement on hand.
Ensure you have all the correct PPE (personal protective equipment) such as safety glasses, gloves, and clean rags to clean up any hydraulic oil.
Preparatory Steps
1. Powering off the Hydraulic System
Ensure that your hydraulic system is off before beginning the bleeding of the hydraulic fluid from the hydraulic lines into the system.
2. Identifying Bleed Points and Components
The bleed valve is used to release trapped air and excess pressure. This empty cylinder is what you use to bleed the hydraulic system.
You should begin with the bleed valves furthest away from the pump and work your way in.
3. Positioning of the System for Effective Bleeding
Ensure you are working with hydraulic equipment on a level surface to ensure effective bleeding of the hydraulic system.
Bleeding Process
Here is your step-by-step guide on how to bleed air from a hydraulic system.
1. Opening the Bleed Valve(s)
You will need to turn the bleed valve(s) anti-clockwise until it is completely open.
2. Allowing Air to Escape
You might be able to hear any trapped or compressed air, escaping or you might be able to see bubbles in the hydraulic fluid.
3. Closing the Bleed Valve(s) When Fluid Flows Smoothly
When there are no longer any air bubbles still in the fluid you can close the bleed valve by turning it fully clockwise.
Testing and Final Checks
Now you have bled the hydraulic system, you need to perform a few checks to the hydraulic cylinder to ensure it is running safely and effectively.
Activating the Hydraulic System to Ensure Proper Operation
Start up the system and check that the pressure is at its proper level. If the pressure is low there may be more trapped air pockets that you may need to bleed out.
Observing for any Unusual Sounds or Behaviors
Listening carefully to the system for any knocking sounds or the hissing of escaping air from hydraulic cylinders for example and observe any other signs that the hydraulic system is not running as it should. If this is the case turn it off and try to locate the source of the problem.
Double-checking for Leaks or Loose Components
If you are hearing noises, there could be low fluid pressure or another sign that the system is not working as it should. In this case, begin by double-checking that there are no loose connections or leaks.
Final Safety Precautions and Recommendations
Many system manufacturers recommend hiring a professional hydraulic systems engineer to bleed the hydraulic system and to check over any issues that you are having. This is not only to ensure that no further damage is done unknowingly but also to ensure the health and safety of any operatives. Work on a hydraulic system should always be undertaken by someone competent and who knows what they are doing.
Conclusion
Regular maintenance checks by a qualified and experienced hydraulic engineer will help your system run effectively and safely and prevent you from needing to bleed air from the system yourself.