Hydraulic fluid contamination can cause severe damage to hydraulic systems. To effectively deal with contamination, it is important to know the potential sources. Identified in this article are six major sources of contamination for hydraulic systems and components along with recommendations for minimizing contamination.

#1 – Hydraulic Fluid Contamination During Production

First, you should be aware that new hydraulic fluid has, on average, an ISO 4406 Cleanliness Code of 17/16/14 to 20/18/16. This is higher than what most manufacturers recommend for their equipment, but experts agree that even this level of cleanliness is not enough for modern hydraulic systems.

So where does the contamination come from during hydraulic fluid production? The facilities that produce hydraulic fluid may inadvertently introduce contamination during processing or mixing. They rarely have control over how the hydraulic fluid is stored, which opens other avenues of contamination. That is why so much emphasis is placed on filtering all fluids that go into a hydraulic system — even a fresh pint of hydraulic fluid could already be contaminated.

#2 – Hydraulic Fluid Contamination During Storage

You may think that storage is the safest place that hydraulic fluid could be, but this is not necessarily the case. Moisture can access the interior of sealed, waterproof plastic containers through what is known as “breathing.” Breathing becomes an issue when a container is exposed to variations in temperatures, such as containers stored outside where the sun might shine on them during part of the day. Even though it’s not possible to see moisture contamination, it can still be very damaging to a hydraulic system’s performance and the system itself.

Of course, containers that are not sealed tightly or are left open pose another major opportunity for contamination — such as moisture, dust, and other debris — to enter. The best way to prevent storage-related contamination is to store fluids at a controlled temperature, lay the containers on their sides, and always carefully seal fluid that is not in use.

#3 – Contamination During Fluid Transfer

Fluids that are exposed to the atmosphere during transfer and handling run the risk of absorbing moisture, as well as becoming exposed to dust and other particles that may be in the air. If the environment where the transfer is taking place is not clean, and the equipment being used is not clean, contamination will most definitely take place. In addition, failure to flush the system before adding the new fluid can worsen the contamination, and mixing fluids can result in chemical reactions that contaminate the fluid.

To minimize the chances of this type of contamination being introduced into a hydraulic system, follow these steps:

• Always flush the system before adding fresh fluid;
• Do not open the fluid in an area that is not clean;
• Do not leave the lid off the fluid longer than necessary; and
• Always filter all hydraulic fluid before adding it to the system.

#4 – Built-In Hydraulic Fluid Contamination

It may be surprising, but it is possible that contamination is built into a hydraulic system during the manufacturing process. Maybe a sand cast part in the hydraulic motor has a few specks of casting sand left inside. Perhaps there is a tiny remnant of Teflon sealing tape on a hydraulic port. There may also be grease or other lubricants that weren’t completely wiped off as the pump was assembled. Any one of these situation can contaminate the system.

Built-in contamination is addressed through the appropriate use of filters, which includes changing filters out on a regular schedule and careful handling of the filters when they are installed.

#5 – Fluid Contamination During Service

During service, contamination can occur when the fluid is exposed to higher than normal temperatures. In addition, hydraulic fluid naturally degrades over time, which is why manufacturers recommend that the fluid be changed on a regular basis.

Fluid can also be contaminated through the ingestion of air and moisture. Seals can be another source of contamination, even when they are not leaking. Tiny particles can ride into the system on cylinder rods and depend on internal filters to capture them.

Contamination can also be generated by the components themselves, like the bearings on a hydraulic motor or the seals on a hydraulic pump, when tiny pieces of particulate matter, metal, or polymer come loose and remain in the system until they are filtered out.

When you suspect the fluid has ingested some type of contamination or been exposed to high temperatures, or when you have reason to believe its properties have begun to degrade, the system should be flushed and new, filtered hydraulic fluid should be added. The ingestion of air and moisture can be mitigated using vacuum breakers, vacuum reservoirs, and air breathers. Seals should be replaced as suggested by the manufacturer, or whenever a leak is suspected. Filters should also be changed regularly.

#6 – Contamination During Maintenance

Finally, another notorious source of hydraulic fluid contamination is maintenance. There are so many possible ways contamination can be introduced during maintenance that it’s best to just talk about how to prevent it.

First, the exterior of the components should be cleaned off, especially if they are used in a dirty environment (e.g., hydraulic motors used on construction equipment). Only use clean, lint-free cloths. Cap hoses and plug ports as soon as they are opened. All hoses and fittings should be handled carefully. New components such as seals and filters should not be removed from their packaging until they are going to be installed. These proactive measures are vital in preventing contamination during maintenance.

Hydraulic Repair Service in Philadelphia

The expert technicians at MAC Hydraulics are available to handle the maintenance and service of your hydraulic systems with speed and efficiency. Whether the work involves pumps, valves, cylinder rods, hydraulic motors, or complex hydraulic systems, we will not only provide you with repair and rebuild services, but we will keep your equipment maintained and in top working condition with our extensive on-site service options. Leave the worry about hydraulic fluid contamination in your key hydraulic systems to us.