When facilities look to improving sustainability, they tend to focus first on traditional energy utilities – natural gas, heating oil, electricity and water. As facilities achieve greater sustainability through efficiencies that reduce utility energy waste and minimize the plant’s carbon footprint, they begin to focus on other energy sources, including compressed air, to enhance sustainability efforts.
Facility engineers recognize that they can lower energy costs by recovering the heat generated by the air compressor, the heart of many critical commercial and industrial processes. They understand that the efficient operation of this vital power source can play a role in meeting sustainability goals. However, they may not recognize the importance of the lubricant – the lifeblood of the air compressor – in promoting efficient operation.
In an effort to reduce costs, users often buy standard, all-purpose mineral oils for lubricants regardless of the air compressor application. While this practice initially lowers operational costs, an overlooked root cause of air compressor downtime or failure can be the choice of lubricants. Purchasing a high-quality synthetic lubricant formulated specifically for the air compressor application can ultimately reduce Total Cost of Ownership (TCO).
The Role of Air Compressor Lubricants
Air compressor lubricants have four key roles:
- Coating to inhibit corrosion
- Coolant to remove heat
- Lubrication to minimize friction
- Sealant to prevent air leakage
Standard mineral compressor oils are suitable for applications that don’t require continuous use. However, their composition makes them an inherently poor choice for industrial applications. Mineral oils have low transfer properties, which cause them to overheat. They are volatile with low flash temperatures and are more likely to evaporate and be used up quickly. Standard mineral oils contain sulfur, nitrogen, and oxygen, which collectively increase acid development, oxidation, and buildup (sludge). The molecular composition of standard oils tends to cause inconsistencies in surface lubrication that increases friction between air compressor parts.
Air compressor lubricants can promote sustainability.
The Benefits of Synthetic Lubricants Optimized for Applications
The benefits of synthetic lubricants chosen for specific commercial manufacturing and industrial applications include the following.
1. Oxidation Resistance
Sludge is a common problem in air compressor use. It is caused not only by poor compressor maintenance, but also by using mineral oils and synthetic products that are prone to oxidation. When inferior products are used in high heat applications, the oil and varnish break down more quickly and require more frequent changeouts that increase equipment downtime.
The oxidative stability of many synthetic lubricants contributes to their high usage per hour, extending parts life and lowering the costs of parts over the life of the compressor. Selecting a high-performance synthetic lubricant with additives that minimize oxidation can increase uptime, save on parts cost and thereby contribute to sustainability goals.
2. High Energy Efficiency and Extended Drain Intervals
Selecting a lubricant based on the air compressor’s operating conditions is key to achieving optimum energy efficiency and extended drain intervals. In commercial and industrial applications where an uninterrupted power source is vital, the primary role of the lubricant is to serve as a coolant so the compressor doesn’t overheat. Synthetic lubricants offer outstanding thermal stability versus mineral oils. The additives in synthetic lubricants enable air compressors to run at lower temperatures which results in increased energy efficiencies that lower energy costs.
Synthetic lubricants also last longer in many air compressor applications. For example, while the life of a mineral oil used in a rotary screw compressor typically is about 2,000 hours, the life of a synthetic lubricant can range anywhere from 8,000 to 12,000 hours depending on operating conditions (e.g., discharge temperature, humidity, cleanliness, and contaminants generated from air intake).
Because so there are so many variables to consider when choosing a synthetic lubricant, it’s advisable to consult with highly experienced lubricant manufacturers that offer a broad product portfolio. One size does not fit all, and the ability to consult with technical experts who can discuss your sustainability goals may be crucial to meeting them.
3. Friction Reduction
Unlike mineral oils, synthetic lubricants are formulated to minimize friction. Reducing friction in air compressor operation results in longer parts life, which lowers the cost of parts over the life of the compressor, and reduces downtime for changeouts. This can result in significant cost savings for continuous use applications.
4. Optimal Viscosity
Lubricants must be thick enough to reduce friction but not so thick that they slow air compressor operation. Choosing the right lubricant viscosity is dependent on the design of the compressor, the type of lubricant required, and the discharge temperature and pressure. Consulting with the lubricant manufacturer can help ensure optimal viscosity for a given operation.
5. Higher Flash and Fire Points
Synthetic lubricants have higher flash and fire points than mineral oils, and some synthetics are designed specifically for use in fire hazard areas and in environments with extreme temperature ranges.
Lubricant selection can impact sustainability goals.
Potential Sustainability Gains
Sustainability gains through proper air compressor lubricant selection can include the following.
1. Reduced Expenditures for Parts
Synthetic lubricants that minimize oxidation reduce parts wear. Parts last longer when synthetics are used, resulting in less frequent changeouts that lead to cost savings. Additional savings are often achieved because in many applications different parts are changed out simultaneously regardless of wear (e.g., lubricant, filters, bearings and separators). While cost savings will vary depending on the application, contributions to sustainability goals can be significant.
2. Lower Maintenance Costs
Since changeouts are less frequent with synthetic lubricants, labor costs are reduced and equipment uptime is maximized.
3. Less Waste
Using a long-life, 12,000-hour synthetic lubricant reduces waste, which promotes greater sustainability. Oil carryover is reduced, which leads to fewer compressor top offs.
4. Decreased Energy Costs
Synthetic lubricants have very low coefficients of friction and superior heat transfer characteristics that lower operating air compressor temperatures for greater energy savings. Switching from a higher viscosity mineral oil to a lower viscosity synthetic can result in improved energy efficiency.
5. Reduced CO2 Emissions
Increasing energy efficiency by using a lubricant with low friction coefficients and superior heat transfer properties also results in reduced CO2 emissions. Synthetics, especially low viscosity oils (LVOs), can help meet sustainability goals.
6. Improved Health & Safety
Synthetics have higher flash/fire/autoignition temperatures than mineral oils and therefore are inherently safer to both use and store.
Because synthetics lubricants reduce maintenance requirements and minimize downtime, they help reduce stress and workload demands placed on busy service and repair teams. Reduced changeouts are especially important for applications that require intense physical effort in uncomfortable working environments.
7. Able to Meet Environmentally Considerate/Biodegradable Criteria
Lubricants can be comprised of high-performance biobased materials and also be environmentally considerate. Biodegradability has many definitions. Technically, all lubricants are biodegradable, but only “readily biodegradable” lubricants will meet sustainability goals. The key is to select a lubricant with low toxicity and non-bioaccumulative properties.1
The Importance of the Supplier in Selecting Lubricants
Choosing a lubricant to achieve optimal air compressor performance can be challenging because operating conditions and regulatory requirements vary widely by industry and application. Significant sustainability gains can be made by working with a lubricant supplier who meets these criteria.
Understands the Importance of Total Cost of Ownership
Many suppliers solely focus on air compressor selection without considering TCO. This short-sighted approach is a barrier to achieving long-term sustainability goals. A supplier with an understanding of both air compressor equipment and a wide variety of lubricants can consider the entire range of factors that affect operation and that ultimately can help lower TCO. A superior lubricant supplier will have performance data and test results to back performance claims.
Possesses a Problem-solving Mindset
A supplier with a problem-solving mindset will work with management and facilities and service teams to understand specific application needs and sustainability goals. Every application is different. Partnering with a supplier with an abundance of high-performance lubricants formulated for diverse uses can be key to optimizing equipment operation and improving sustainability.
Has Industry Knowledge and Experience
Suppliers who are familiar with environmental operation conditions in your industry as well as regulations can be an invaluable in selecting lubricants. Here are two examples of successes in the industry:
Cement plants are notoriously dusty, dirty environments with unique operational challenges. Dust is sucked into the compressor system along with the intake air, which in combination with elevated humidity levels and high ambient temperatures, can lead to machinery failure and unexpected compressor downtime. One recent study demonstrates how selecting specific high-performance lubricants for cement processing can improve the energy efficiency of screw-type air compressors.2
Food & Beverage Processing
Technology is now available to formulate food-grade lubricants that eliminate varnish and that can achieve significant cost savings, typically 80% in total cost of parts, maintenance and lube. One multi-synthetic lubricant, Klüber FG Elite Series, lasts 8,000 hours before changeouts are required. Innovative chemistry was used to create an NSF Food Grade approved base stock component for use with traditional rotary screw air compressors.
Selecting a synthetic lubricant formulated for a specific air compressor application can promote sustainability. Significant gains can be garnered by increasing energy efficiency and improving equipment reliability. Key benefits can include greater equipment downtime, lower parts and maintenance costs, and reduced waste.
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About the Author
Jasween Jagjit-Webb is Market Manager for Air Compressor Lubricants at Klüber Lubrication. In her role, she is responsible for developing new business in the air compressor lubricant industry. Jasween joined Klüber Lubrication in 2013 and has held a number of positions within the Klüber group. She is an accomplished sales manager with more than 12 years of technical product sales experience in the air & gas compressor industry. Jasween received an M.B.A. from Northwood University and a B.S. in Chemical Engineering from Michigan Technological University.
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1 John Sander, Lubrication Engineers, “Can Lubricants Be Green,” Biomass Magazine, October 2, 2020.
2 Stefan Borrmann & Markus Burbach, Klüber Lubrication, “Maximise Air Compressor Energy-Efficiency with High-Performance Lubricants,” Global Cement Magazine, June, 2021.