Rotary screw air compressors are used to supply large volumes of compressed air for air tools and other industrial applications. Because they are generally used commercially, there is a high need for reliability. As every industrial engineer knows, the key to reliability is reliability centered maintenance.
However, a balance must be struck in establishing a maintenance schedule. A maintenance schedule that is too aggressive can be wasteful because air compressor parts and fluids may be replaced when they are still usable. As a result, maintenance costs are greater than they need to be.
On the other hand, a maintenance schedule that is too lax risks damaging equipment. This leads to expensive repairs and downtime.
One way to strike a balance is to use condition based maintenance. Rather than relying on rigid maintenance schedules, condition based maintenance measures the actual condition of air compressor parts and fluids to develop a model that predicts when failure will occur. Maintenance tasks can then be based on failure projections, thereby maximizing the efficiency of the maintenance program.
Here are three ways that compressor oil analysis can aid in developing an efficient maintenance schedule:
Measure Particulates
Particulates, whether they come from the air intake in the form of dirt or dust or from corrosion and wear of air compressor parts, can lead to failure of air compressors. Particulates can clog oil filters, leading to overheating and inadequate lubrication. Worse yet, particulates can cause abrasive wear of seals and bearings.
Oil analysis can not only identify the volume of particulates in air compressor oil, but they can also identify the type and source of particulates. Metal shavings, for example, would likely originate from wear or corrosion byproducts, while dust or grit likely originates from the air intake.
Through oil analysis, you can determine when compressor oil has so many particulates that it causes more wear than it prevents. You can also identify when air compressor parts have begun to wear or corrode.
Identify Moisture
Water in the compressor oil can cause many problems. Water can cause corrosion by providing an electrolyte for the exchange of electrons across metal parts. Water can also oxidize the oil as it breaks down into hydrogen and oxygen atoms. Oxidation can lead to oil breakdown through acidification. Acidified oil has a different viscosity and chemical makeup that can lead to sludge formation.
Oil analysis can identify the existence of moisture and acids in compressor oil. Not only does this information advise operators when to replace compressor oil, but it can also be used to determine the effectiveness of compressor oil purifiers using ion exchange. Ion exchange technology dates back over 100 years when it was originally used to purify water.
Analyze Oil Additives
Oil additives are what distinguish lubricating oil from the compressor oil. Because compressor oil must seal the air chamber and filter the air intake, additives are used to provide the exact fluid and chemical properties needed.
As additives break down, the oil loses life and performance characteristics. Oil analysis can identify the loss of additives and identify when additive replacements can help restore the compressor oil.
Oil analysis is important for any maintenance program. It can help to set an efficient maintenance schedule based on the actual conditions inside an air compressor.
