Oil chiller Technical Information 3-3.About oil deterioration
3-3.About oil deterioration
It is inevitable that oil deteriorates during use, but degraded oil becomes the great enemy of equipment.
This section explains the causes of deterioration and how to check for deterioration.
What is oil deterioration?
Oil deteriorates during use. There are three main causes of deterioration:
1. Contamination: Generation of sludge, mixing of atmosphere and oil mist
Metal particles generated by wear can directly damage equipment, and the mixed atmosphere and oil mist can affect the oil components, changing the originally expected performance of the oil, such as viscosity.
2.Contamination with moisture
Basically, it is the problem that the oil contains water.
If the water content is 0.1% or more based on the mass of oil, it cannot be used because it will cause rust on the equipment.
3.Temperature change
Oil, which is often exposed to high temperatures, deteriorates due to oxidation and alteration of temperature changes.
Deterioration due to temperature changes is a change in the quality of the oil, so the oil's originally expected performance will be lost.
Degraded mineral oil lubricant additives are the great enemy of equipment
As mentioned in"3-2. About oil viscosity", mineral oil always contains lubricating oil additives.
While mineral oil maintains its functionality when new, this lubricating oil additive works by stably bonding with the base oil, but as the oil deteriorates, the lubricating oil additive separates from the base oil, will end up damaging the metals.
"Sulfur", "phosphoric esters", "phosphates", etc. contained in lubricating oil additives have the effect of corroding copper, which can also affect the steel pipes used in oil chillers, causing equipment damage.
| Types | Purpose/function | Typical inclusions | Additive amount |
|---|---|---|---|
| Antioxidant | Prevents oil oxidation by reacting with free radicals and peroxides to convert them into stable substances, and suppresses the formation of varnish and sludge caused by oxidation. | Organic sulfur compounds Zinc dithiophosphate |
～1% |
| Anti-wear agent | Forms a protective film of secondary compounds on the worn surface to prevent wear. | Phosphoric ester Zinc dithiophosphate |
5～10% |
| Rust inhibitor | Forms a protective film on the metal surface. Or neutralize acids to prevent rust. | Phosphates Ester |
1% |
Preventing equipment troubles through frequent checks and replacements
Preventing equipment troubles due to oil deterioration
Oil will deteriorate sooner or later, and there is nothing to prevent.
What you need to be careful about is that deterioration can lead to loss of its original function or problems with the production equipment itself. To prevent this, it is important to observe the following four points.
・Do not make the mistake of replenishing oil
・Do not forget to check the oil level every day
・Prevent contamination of foreign substances (moisture, metal powder, etc.) as much as possible
・Watch out for changes in the hue of the oil
Determination of oil deterioration by hue ＜Simple colorimetric method using ASTM color＞
The oil changes color to reddish as it deteriorates.
When determining deterioration based on the hue of oil, the approximate oxidation deterioration limit is when the hue (ASTM number) of the new oil is 2.5 or more darker than the new oil.
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