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Four Ways Outside Contaminants Enter Your System

Thu, Apr. 15, 2021

Four Ways Outside Contaminants Enter your System

As an equipment owner or manager, the last thing we want to find in our system is contamination.  After all, contamination means loss of efficiency or even downtime, which ultimately costs time and money.  Contamination somehow always sneaks its way into our systems.  So, how does contamination get in our systems and what are we supposed to do about it?

1. Air Breathing Exchange

One way contamination gets into systems is through air movement in/out a reservoir.  Oil level in a reservoir is affected by the use of components such as cylinders in the system, or due to thermal expansion/contraction of the lubricant.  As the oil level rises and falls in the reservoir, air either fills that void or is pushed out to make room for incoming oil.

What to Do About It

Because air is one of the top four sources of contamination, a high-efficiency air breather should be used at a minimum, or desiccant breather coupled with a headspace dryer if conditions allow, to greatly minimize airborne ingression.  Always filter air exchange with the system.

2. Seals

Seals are another source of contamination, whether they’re cylinder/pump or shaft seals.  When dirt makes its way to a seal, sealing surface or seal itself is damaged from solid particle contamination, resulting in an ingression point for more contamination to enter the system.  This damage also results in a leak point.  Oil loss due to leaking will eventually result in oil refill requirements, plus the sealing surface and/or seals continue to sustain damage, worsening the situation.

Once solid contaminants damage seals or its sealing surface, it starts a non-stop cycle of damage.  We often say in training that dirt makes dirt.  Think of the way an exfoliant scrub will remove more skin cells from hands compared to only rinsing hands with water.  Because the exfoliant is gritty, it results in the removal of more skin.

What to Do About It

To break the cycle of contamination buildup and resulting damage, use high-efficiency filter elements to recover a dirty system.  Use high-efficiency filter elements to maintain a low operating ISO Code under the system limit moving forward.  Strive to maintain a clean system and avoid contamination build-up around seals to extend sealing surface and seal life.  Oil consumption will trend lower as well.

3. Adding Oil

Adding oil is a normal part of maintenance and/or operations responsibility.  If level indicates oil needs to be added, oil is added.  Reasons range from maintenance events to leaks requiring oil be added.

The obstacle we must overcome is recognizing new oil ready to be added to a system is dirty oil.  New oil is new, but not clean.  Oil typically changes hands 6-8 times from the refinery to being added to the system.  Interested in learning more about new oil cleanliness levels, click here How clean is new oil?

What to Do About It

Filter oil before being added to a system.  Filter oil as its added to a system if practical.  We recommend pre-filter oil in a holding container, such as barrel, tote or holding tank.  Pre-filtering allows time to confirm oil cleanliness is under the system limit (ISO 4406:1999) before oil is added to the system.

4. Routine Maintenance

Opening a system for any reason allows contamination to enter.  Oil is sticky, so when an opening in a system is in contact with air, particles in air stick to the oil.  Any opening such as a reservoir lid allows normal fallout to enter the system in addition to air exchange around the lid opening.  Replacing a component such as a hydraulic hose, dirt can enter the system.  Most often forgotten is when a filter element is replaced, dirt has a very easy opportunity to enter the system.

What to Do About It

Routine maintenance is inevitable. When opening a system for maintenance, consider air flow when preparing for the maintenance event.  Temporarily turn off air handling if air flow is in direct line of maintenance.  Big fans in a hydraulic room are an example.  If not possible to temporarily stop air flow, install a temporary shield for use during the maintenance event.

Before opening the system for maintenance, remove all debris around the maintenance location and thoroughly clean around the part of the system to be opened.  Always drain filter housing first before removing old filter element.  Save drained oil in properly marked barrel for cleaning and drying prior to re-use.

When handling the filter element, keep the plastic covering on the filter element, or in the box if it does not have a covering, until right before installing the element in the filter housing. Use lint-free rags around any system opening.


Do you need help with the contamination in your system or have questions about how to prevent contamination from building up?  Give us a shout here at Hy-Pro. We love helping you maintain highly efficient systems!!!

Written by Scott Howard


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