Optimizing air compressor reliability and maintenance costs are vital aspects of ensuring efficient operations in industrial facilities. However, one often overlooked culprit that undermines these goals are the acids found in the compressor’s oil. These acids pose a significant threat to the longevity and performance of oil-injected rotary screw air compressors, and are at the root of reduced oil and component life, frequent maintenance and downtime, and high repair costs. In this article, we’ll delve into the origins of acids, their detrimental effects on compressor oils and internals, and practical steps compressor users can take to mitigate their impact.
The Menace of Acids
What are Acids? Acids, in simple terms, are highly destructive chemical substances found in all compressor oils that are known to be both reactants and catalysts that accelerate oxidation, oil degradation, and corrosion. Acids are a leading indicator of the oil’s oxidative state and its remaining useful life and should be monitored with oil analysis to regularly check its TAN, SAN, and pH.
Sources of Acids
Acids in the form of acid-gases enter the compressor from airborne pollution and chemical vapors present in the atmosphere, the same pollutants that result in “acid rain”. Common acid-gas culprits found in industrial environments include combustion exhausts, cooling tower emissions, welding fumes, process vapors, and industrial cleaners. Additionally, acids are naturally produced internally within the compressor from oxidation, a chemical reaction between oxygen, the oil, and its protective additives.
Impact on Compressor Components
Acids degrade the oil’s physical, chemical, and performance properties reducing its useful life and negatively impacting every component it touches. Acids also deplete the oil’s protective additives leaving the oil and compressor internals vulnerable to attack from oxidation and/or corrosion. And, as acids steadily accumulate in the oil and increase in concentration and strength, they accelerate oxidation to produce more acids and deplete more additives faster and faster, until the oil becomes “brittle” and rapidly fails.
Corrosion and Wear
If ignored, acidic oil can corrode vital compressor components such as sump tanks, bearings, and coolers, generating ultra-fine rust particles that circulate throughout the compressor. Corrosion and its byproducts contribute to the fouling of coolers, separators, scavenge lines, injection orifices, and filters, which increases operating temperatures, oil carryover, and corrosive wear of bearings and shaft seals, ultimately reducing the life of the air-end.
Mitigating Acid Contamination
For the life of the compressor and its oil, every effort should be made to prevent acid-gas contaminants from entering the compressor. This begins by ensuring the compressor, or at least its inlet air supply, is pulling air from a cool, clean, dry area void of any acidic pollutants. In locations where this is not practical, acid-removing inlet air filters are available, but these can be very expensive and only moderately effective. and ensuring thorough oil drainage during changes are essential preventive measures.
Acid Removal
After preventing any external acid-gases from entering the compressor, it’s time to address the liquid acids found in the oil. Fortunately, compressor oil purifiers that combine ion exchange acid adsorbing media with ultra-fine filtration are readily available and proven to be extremely effective at removing acids from compressor oils. These easy to install side stream purifiers/filters continuously removed harmful acids and ultra-fine solids to dramatically increase oil performance, protection, and service life.
Additive Replenishment
Another effective tool for controlling acids in rotary screw air compressor oils is additive replenishment. By proactively replenishing the oil’s protective additives to their new oil levels, users can neutralize existing acids, inhibit further oxidation and acid production, and restore protection to the oil and internal components. Coupled with oil purification, this approach significantly extends oil service life and reduces maintenance frequency and downtime.
Conclusion
Understanding the detrimental effects of acids on rotary screw air compressors and their oils is paramount for optimizing reliability and minimizing maintenance costs. By implementing preventive measures, utilizing today’s acid removal technologies and adopting proactive additive replenishment, industrial air compressor users can enhance their compressors’ performance, prolong component lifespan, and deliver substantial cost savings.
When combined with a proactive reliability-centered maintenance strategy, compressor oil purification and additive replenishment are proven to produce a 5-10-fold increase in oil service life, or up to a 90% decrease in oil consumption and oil change related downtime.
Fluid Metrics stands as a leader in compressor oil formulation and contaminant control technologies. Contact us today to discover how our solutions can help you effectively manage acids, improve compressor reliability, and optimize your operations.