Everyone Wants to Live Forever Pt II

At long last, part two of my article series on fluid cleanliness. I’d like to thank both of my readers for your attention and one of you for your kindly suggestion that I “learn how to write.” I will take that into consideration.

Today I will be answering the burning questions I left you with in our last installment:

• Why is oil cleanliness important?
• How does it affect me?
• What is the meaning of life?

Why is oil cleanliness important?

That’s a great question. First it might help to delve into just how dirty your oil can get. How many particles per minute do you think will ingress to your equipment in your environment? 10? 100? 1000? 10,000? I’m afraid I have some rather bad news for you, the average ingression rate of particles of 10μ or less for an assembly (clean) facility is 100,000 – 1,000,000. For a manufacturing facility it is 1,000,000 – 100,000,000. For mobile equipment it’s up to a billion! Per minute!! I can’t use enough exclamation points to emphasize how shocking that is to me!!!  

But Dave, you ask, why is that bad and why should I continue to waste valuable coffee break time reading your article? Another fine question that I am sure will be debated long after I’m gone. Let’s simplify things here. Why do we have to replace equipment? Because it’s no longer useful to us. That was easy – and remarkably obvious. But how does equipment become no longer useful? There are three factors, essentially. Obsolescence - this equipment is either not able or cannot efficiently meet the demands of the application due to advancements in technology or change in methods, or the application itself is no longer viable. This accounts for about 15% of the total loss of usefulness. Accidents – fires, floods, lightning, earthquakes, alien invasions (the latter not covered by insurance, by the way). Those account for roughly 10%. The remaining 75%? Surface degradation. Of that 75%, only 25% of that is due to corrosion while the remaining three quarters is mechanical wear.

Now we’re really getting into the weeds of a simple concept. How does mechanical wear break down? Abrasion, fatigue and adhesion. Each of these issues can be caused by flawed lubrication – A.K.A. contaminated oil. It gets worse, too. If particulate is your poison, forcing dirty oil through your equipment is like a liquid sandblast, it just creates more dirt. Whenever a chunk of contamination wears away at part of your equipment, the tiny bit that breaks free has to go somewhere, and that place is into your oil, joining forces with the millions of other chunks that are attacking it in the first place. Think of it like a zombie outbreak: every person that gets bitten then becomes a zombie and goes to bite others – who in turn, become zombies and so on. When a particle collides with a surface and breaks a particle free, there are then two particles. Those two proceed to break (bite) other particles free, which then become four particles, then eight – and so on.

It’s a zombie apocalypse of epic proportions on a microscopic scale! 

From this we can gather the oil cleanliness is important because oil contamination is shown to be bad - exactly like zombies but with less blood and probably not as smelly.

How does it affect me?

I should hope by now that would be obvious, but let’s look at some numbers. The above graphic shows recommended upper limit ISO cleanliness codes per component by pressure rating. Great, but what does that mean? I imagine to you, the intelligent reader, that’s obvious. But I’ll explain for the others. Remember last week when I posted that boring article about ISO cleanliness codes? You may need to refer back to that when you look at the chart.

Example: For a fixed vane hydraulic pump running a pressure of 2000-3000 psi, it is recommended that your cleanliness code for the fluid in this pump be 19/17/14. From last week's chart we know that this means that the 4μ channel should have 2,500-5000 particles per milliliter, the 6μ channel should have 640-1,300 particles per milliliter and the 14μ channel should have 80-160 particles per milliliter. That’s pretty darned clean when you consider that your hydraulic sump can be contaminated by as much as 100,000,000 particles in a single minute. And that’s just the industry recommendation, not our recommendation (which is tougher).

So to answer the question, "How does this affect me?" – it’s clear that your hydraulic pump (or valve, or gearbox, or bearing or whatever) wants to have oil set to a certain standard of cleanliness in order to maximize its usefulness to you. We’re not talking about clean oil for the sake of saving oil, we’re talking about getting your oil cleaner for the sake of saving your expensive equipment. This leads to more questions: How can I get clean oil, how will that help extend the useful life of my equipment, and what is that little flanged thingie that keeps turning up in my junk drawer, you know, the one that looks like it’s made of galvanized steel and has a screw hole in it? For those answers, you’ll have to tune in next week.

In the meantime the answer for question number three – "What is the meaning of life?" Should now be obvious to anyone who has been reading.

See you next time.