Fast vs. Slow Oxidation Explained

Dec 22, 2021

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Many different industries, from pharmaceutical and life science companies to food and beverage businesses, rely on high-quality compressed air to get their jobs done. With such a need for compressed air, it is crucial to have a general knowledge of the application and a compressed air specialist company to count on for any questions or concerns.

If your industry is one of the many that relies on compressed air, then it is important to understand the basics of air compressors so you can make informed decisions about the right air compressors for your company. One important thing to understand is the possibility of oxidation and how it affects the air compression system. Oxidation is the reaction that occurs when a chemical substance changes due to oxygen exposure. However, oxidation is a much more complex reaction with two different forms — fast oxidation and slow oxidation.

In This Article

Fast Oxidation

Fast oxidation is a type of oxidation that rapidly occurs, causing an immediate reaction. Fast oxidation — commonly used to describe combustion — is hazardous because it involves the addition of oxygen to an environment already permeated with heat. Adding oxygen to an already heated extreme environment can cause fires and explosions.

One example of fast or rapid oxidation is how a gas stove works. When you turn a stove on, you release gas through the valve and piping system. This system ends where the stove has a small hole that takes in oxygen, causing a combustion reaction when the oxygen meets the gas.

Another example of fast oxidation is in airplane tires, which require minimal oxygen because of the heat they produce during launch and landing. If the tires have too much oxygen, this added heat can cause them to explode or combust.

Slow Oxidation

The other type of oxidation is slow oxidation. This form occurs over a longer period of time compared to fast oxidation. Unlike fast oxidation, slow oxidation does not produce light or noticeable heat. Instead, objects affected by slow oxidation become ruined slowly over time.

One common example of slow oxidation is spoiling produce, such as fruit. If you leave a piece of fruit out for too long, it becomes discolored and rotten. The extended exposure to oxygen is what causes this discoloration. Other similar examples of slow oxidation are food turning moldy, metal corrosion and rotting wood.

All of these changes occur over a period of time without any extreme reactions like flames or heat.

How Oxidation Impacts Air Compressor Lubricants

After understanding the basics of fast and slow oxidation, you should know how these processes can affect your air compressor lubricants. Like most fluids, you can determine the end of your air compressor lubricant’s useful life when it oxidizes to the point where it does not function properly. Some characteristics of over-oxidized lubricant are that it thickens, produces heavy deposits and becomes high in acidity.

Air compressors have a unique threat in their lifespan that other lubricated components do not due to the constant influx of high temperatures, oxygen and water levels. Each of these forces can cause the lubricant to degrade through oxidation, leading to problems with your air compressor.

Your air compressor works by bringing in oxygen. When the lubricant has constant exposure to oxygen, this forces the compression of the air to release moisture and generate heat. The moisture from the air’s humidity and the heat it causes makes the oil condense.

Oxidation degrades air compressor lubricants, so once the lubricant has oxidized, you need to replace it. If you do not, this can damage your air compressor. Oxidized oil can cause equipment corrosion and varnish, the by-products of the degradation of air compressor lubricants. This oxidation can produce long-term effects that decrease the machine’s efficiency.

How to Test Air Compressor Lubricants for Oxidation

With this knowledge of how oxidized air compressor lubricants can negatively affect your air compressor, you should know how to test your air compressor lubricants for oxidation to ensure a properly working machine. There are multiple tests available to gain information about lubricant oxidation.

One method many people use to test the oxidation of their air compressor lubricants is the Rotating Pressure Vessel Oxidation Test (RPVOT), which determines the oxidation stability of the oil. The RPVOT test measures the oxidation resistance. You can perform this test by placing a lubricant sample into a glass chamber with a copper catalyst and water, which you then seal, purge and pressurize with oxygen and heat. This environment mimics an air compressor chamber, giving you an idea of how much oxidation your air compressor lubricant can stand before degrading.

Another test you can use to check the useful life of your air compressor lubricant is the ASTM D7843 test. This method uses a membrane patch colorimetry (MPC) to measure the oil’s varnish potential. Once you prep the oil and run it through a membrane, the membrane captures insoluble substances, changing the color of the patch. The patch color determines the state of your lubricant, rating it as “good,” “monitor,” “abnormal” or “critical.”

One more basic test you can perform on your air compressor lubricant is routine oil analysis. This analyses the viscosity, acid number, water, additive metals, wear metals and possible oil oxidation in your air compressor, which you can then test against the oil baseline. Two of the most important aspects this test reveals are kinematic viscosity and acid number, primary indicators that oil is close to the end of its useful life.

Contact Fluid-Aire Dynamics Today

If you are looking for a reliable compressed air and gas system specialist company, look no further than Fluid-Aire Dynamics. For almost 30 years, we have provided our customers with reliable and knowledgeable solutions to compressed air and gas problems.

Serving various industries — including military, energy, chemical, pharmaceutical, food and beverage and manufacturing — we can help if you need high-quality compressed air to run. We offer air compressors of varying types and sizes to suit the needs of your specific industry and can service small companies to large corporations.

If you are looking for a compressor air specialist with superior capabilities and product offering in the design, engineering, installation and maintenance of compressed air and gas systems, Fluid-Aire Dynamics may be the right choice for you.

Contact us today with any questions about your compressed air needs and how we can help you achieve your goals.

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