Contamination of hydraulic fluid by solid particles from the dusty environment of the field can dramatically reduce the life of mechanical components, mainly because such contamination increases the wear rate, decreases the efficiency of the hydraulic system and consequently reduces the availability and productivity of the equipment in the field. Small dust particles, which are extremely abrasive, can enter the system by increasing the wear process on critical and expensive components such as piston pumps. This contamination also slows down and even blocks the movement of valves in the hydraulic system.
As these particles are virtually invisible to the human eye, the control of contamination of the hydraulic fluid is often neglected by the farmer or by maintenance. Further aggravating the damage to the equipment. Studies indicate that about 70% of premature failures in hydraulic systems are caused by contamination of the hydraulic fluid. Increasing maintenance costs considerably. The losses are even greater if we include the loss of productivity in this account.
The size of a particle is measured in microns. Since the smallest particle we can see is those with at least 40 microns, which is the particle size equivalent to the dust that is probably accumulated on the screen of your computer or television. However, the particles that cause damage to the equipment are smaller, and range from 5 to 15 microns. It is this particle size that can travel through the entire hydraulic system. Passing through the gaps between the components, being deposited in critical parts causing the total or partial obstruction of the holes of the hydraulic system.
Upon entering the gap, this solid particle may also generate new particles through the wear generated on the metal surface. Among these types of wear, they are more common:
– Abrasive wear: occurs when a hard particle removes metal from the surface of the component during its movement;
– Fatigue Wear: occurs when the force of the present charge is transferred through the particle to the metal surface causing small metal particles to loosen, the common effect of this type of wear is pitting;
– Erosive wear: when the impact or collision of a harder particle on the metal surface causes local erosion.
How to control contamination in the hydraulic system?
In order to control the level of contamination of the hydraulic fluid, we must first discover the current level of contamination of the fluid. And compare with the parameters recommended by the equipment manufacturer or industry standards. To quantify the level of contamination, it is necessary to collect a sample of the hydraulic oil. And refer to a lubricant analysis laboratory for particle counting tests. The most commonly used particle counting assays are ISO 4406 and NAS 1638. They measure the amount of particles within a certain volume of oil and quantify these particles by size range.
Tips to avoid this problem:
- Choose to use a good quality hydraulic fluid;
- Pre-filter the oil before returning it to the equipment;
- Properly store the hydraulic fluid in a contamination-free location;
- Always keep the reservoir supply nozzles tightly closed and free of dust;
- Handle hydraulic fluid carefully to prevent contaminants from entering;
- Regularly change system filters;
- Perform fluid analysis regularly including the particle count test;