Why You Must Eradicate Contaminants from Your Lube Oil

Regardless of contaminant type, any lube system will be compromised if contaminated.  The effect can then compound as some contaminants have a catalyst effect, causing further problems.  The types of contaminants are quite varied including hard particles, soft particles, moisture and free water, gas and varnish.

Over the next few articles we will cover the range of issues that you should consider when managing your lubrication oil for close tolerance machines, hydraulics and gearboxes.

What you cannot see is doing the damage

Silica & Bright Metal at 100x
Let’s start with the types of contaminants:

1. Hard particles, such as Iron, Chrome and other metals, Silica and sand
2. Soft Particles, such as Copper, Tin and other soft metals, fibres
3. Soluble contaminants, varnish, incompatible top up lubes or additive packages
4. Gases and Aeration, process gases and aeration from ingression or inadequate system design
5. Water and liquid contaminants that can change lube viscosity

Hard particles will score and wear away lubricated surfaces, producing other contaminants in the lube oil, creating a snowball effect of increased wear rates. Wear particles and contaminants that oxidise, will deplete the antioxidants in additive packages, leading to varnish potential.

Soft contaminants have the potential to damage lubricated surfaces and increase wear rates, as well as depleting antioxidants, plugging filtration systems and galleries.

Varnish is a by-product of contaminants or depleted antioxidants, and a real concern in any lube system as the damage caused by varnish includes sticky and gummed valves and actuators, decreased tolerances which restricts lubrication to the wearing components causing higher operating temperatures.  Varnish can also plate out on bearing surfaces, causing hot spots and journal deformation. There are costs associated with varnish removal, but the real costs are downtime and loss of production.

Gas - In processing industries, where gas is present, such as gas compression facilities, lube oil can become entrained with gas, becoming aerated and not supplying the correct oil film or strength to the lubricated surfaces, as well as reacting with other contaminants in the oil to cause varnish potential. Aeration in hydraulic equipment also causes cavitation, prematurely wearing pumps, controls and work accessories.  Aeration and cavitation in lubricating oil destroys components and pumps, and reduces operating efficiency.

Moisture in oil is a common contaminant, as our climate can be humid with a wide temperature range.  In close tolerance rotational equipment, moisture levels below 200 ppm are acceptable but some OEM specifications allow for much higher.
                                                     
Free Water has a devastating effect on bearing surfaces, as the water droplet compresses and becomes super-heated into steam, exploding and 'etching' the bearing surface, rendering it unserviceable.

Magnified Samples (60x & 100x)

The following slides are all pictures taken by BioKem Oil Services in the last year.  They show a range of contaminants in 100ml samples of lube oil from gas compressors, turbines, steam feed pumps and gearbox lube oil tanks. For reference the black line shown is 44µm in width.

RUST – The presence of water speeds oxidation and additive breakdown of the oil and is considered a serious problem.  Particle size varies from 10 - 120 micron range

FIBRES - Typically introduced by improper cleaning and maintenance practices.

ASPHALTENES - particles are generally in the 0.5 - 2.0 µm range and they agglomerate into an oily sludge. This problem is made worse when free water is present.

SILICA & SAND – range of debris on this slide typically found airborne in Australia.

BRIGHT METAL PARTICLES - Typically comes from component wear. These particles are abrasive and, as a result, can lead to further wear and tear of the system bearings.

SOOT & SILT (<5µM), SILICA AND DUST PARTICLES - This is typically airborne contamination or part of sludge from the bottom of tanks.  Very hard and extremely abrasive against delicate components in boundary layer systems.

Non Magnified Samples

Sludge – This is a filter housing showing a buildup of oil additives after exposure to moisture (no magnification)

Varnish – Flakes of varnish plated out onto a filter and the varnish washed out onto an an absorbent towel (no magnification)

Examples of Damage

The next few articles will focus on how the different contaminants are caused, and the types of resolutions that can be performed.
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