As we have covered before, contamination of hydraulic fluid can cause a lot of different issues to the system. Therefore, removing this contamination can prevent damage and failure of the system. The approach we are covering here is the practice of flushing.
The damage that can be caused by contamination includes internal leakage, flow and pressure issues. This can lead to wasted power and an increase in heat to excessive levels. There is also the possibility of parts sticking due to there being silt or sludge in the system, which can even lead to seizures when there are large amounts of contaminants present.
Contamination can be caused by particles or by water or air. Moisture can cause many problems in the hydraulic system. When dealing with this issue, most engineers recommend that a lower viscosity ‘bog standard’ fluid is used to flush the system, one without any expensive additives in combination with a rig.
To get the best results, the flushing would take place in both directions with the fluid at a temperature of around 140°F with turbulent flow in effect. Usually turbulent flow is to be avoided, but when flushing is taking place, it’s important to do what’s possible to aid the dislodgement and removal of contamination.
This is also another reason why using low viscosity fluid helps. What rate of flow you’ll need to reach turbulent flow conditions will depend upon the diameter of the inside of the conductor.
The flushing rig must be able to generate a flow rate that is more than what the hydraulic system has been designed for.
How long you’ll need to do this for will depend upon what your particle rates are. They should be monitored and recorded regularly to avoid damage. Not doing so could become a costly mistake.