Outsourcing maintenance agreements for compressed air systems is commonplace in the food and beverage industry. The maintenance programs are often performed by air compressor distributors, who are experts in the specifics of the air compressors and compressed air systems they sell and service.
What can’t be outsourced is the damage to your brand’s reputation if there is a catastrophic failure or contamination event associated with a compressed system. That’s why it’s more important than ever to stay involved in the details of one of the most important systems in your facility.
The importance of staying closely involved in the details of a compressed air system maintenance program – and the lubricants used – cannot be understated for food and beverage companies.
Food-grade Lubricants in Food and Beverage Applications
Since the Food Safety Modernization Act (FSMA) was enacted in 2011, food-grade lubricants have increasingly become the standard for air compressors powering food and beverage facilities. Prior to that, air compressors were rather late adopters of food-grade lubricants because air compressors are not typically located in the processing area of the plant.
Hazard Analysis and Critical Control Point (HACCP) regulations place the responsibility for the integrity of the product directly on the processor. Food-grade lubricants should be used if plant air is identified as a Critical Control Point.
In the United States, lubricants are considered food grade (H1) if they are formulated using ingredients the U.S. Food and Drug Administration (FDA) lists as appropriate in incidental food contact lubricants at their prescribed levels or other ingredients such as US Pharmacopeia (USP) white oils or Generally Recognized as Safe (GRAS) substances.
Food-grade lubricants use a classification system originally developed by the U.S. Department of Agriculture (USDA) and adopted by the National Sanitation Foundation (NSF). In 1999, NSF International launched its voluntary Nonfood Compounds Registration Program. Products eligible for NSF Registration include all compounds used in and around food establishments (nonfood compounds) — such as disinfectants and lubricants or fruit and vegetable washing agents.
Additionally, H1 air compressor fluid performance was limited in terms of life of the lubricant and deposit control within the air compressor. These systems became more of a target for food-grade lubricants once Hazard Analysis and Critical Control Point (HACCP) regulations came into play as part of the FDA Food Safety Modernization Act (FSMA). HACCP regulations place the responsibility for the integrity of the product directly on the processor. If plant air is identified as a Critical Control Point, then food-grade lubricants should be used.
Match the Oil to the Compressed Air Application
Undervaluing the fluid protecting your compressed air system can be an easy, but critical oversight. To maximize system performance, the oil chosen for your compressed air system should be matched to your specific facility, not just a general spec. While the manufacturer’s recommendations are a great place to start, air compressor lubricants must also address the real-world conditions that exist in your plant.
For instance, supply side air quality is a huge factor in determining the demands on air compressor lubricants. The ambient air is a serious concern for rotary screw air compressors where the entire flow of air through the air compressor will directly impact the fluid. In addition to lubricating bearings, the fluid is effectively acting as a scrubber to absorb the acids and contaminants.
Even a low concentration of inlet air contamination is significant, when the sheer volume of air being handled is considered. Downstream components, such as after-coolers and dryers, are also often compromised by corrosion caused by acid gases which pass through the air compressor from the environment. These gases then condense with water in the coolers and dryers and drastically increase corrosion rates.
Choosing the Right Lubricant
The simple truth is that a wide array of lubricants can protect a compressed air system at a very basic level. Most lubricating fluids that include a base oil, antioxidants, and some level of anti-wear and corrosion inhibitors can work in an air compressor. But that doesn’t mean they are the best choice for your facility.
First off, food and beverage processors should be using NSF H1 food-grade lubricants in their compressed air systems. A single contamination event can do irreparable harm to your brand reputation.
It’s been well documented that first-generation of food-grade lubricants did not deliver the performance needed for food plant compressed air systems. Part of the reason for this is that many early food grade lubricants used plain mineral base oils. While mineral oil provides excellent lubricity, it has a relatively low oxidation stability.
Second-generation, food-grade lubricants utilize the synthetic base oil Polyalphaolefin (PAO). PAOs are a synthetic hydrocarbon that offer excellent lubricant life and thermal oxidation stability, but when used exclusively in an air compressor fluid formulation can present deposit and lubricant life issues. The most recent offerings in food-grade air compressor lubricants will often offer blends of synthetic fluids and additives that greatly improve performance over first and second-generation fluids.
Recent food-grade air compressor lubricants often offer blends of synthetic fluids and additives that greatly improve performance over first and second-generation fluids.
Oil Oxidation Stability: The No. 1 Requirement
The No. 1 requirement for air compressor oil options is oxidation stability. Oxidation is the chemical reaction that occurs between a lubricating oil and oxygen. The rate of oxidation increases over time, and is significantly accelerated by high temperatures, water, acids and catalysts. The results are dire for compressed air systems. Viscosity increase, varnish, sludge and sediment formation, additive depletion, base oil breakdown, filter plugging, loss in foam control, acid number increase, rust formation and corrosion can all have damaging impacts on system efficiency.
Since controlling oxidation is key, every air compressor lubricant formulation contains antioxidants. These antioxidants are designed to be sacrificial, meaning they react before the remainder of the lubricant (the base oil) to provide protection. This protection is a critical mechanism in saving the lubricant from premature failure due to oxidation. The right amount and combination of antioxidant additives and synthetic base fluids is key to ensuring longer change intervals, reduced downtime, and longer equipment life.
One method lubrication chemists use in the laboratory to determine desired levels of antioxidants is Thermogravimetric Analysis, or TGA. Remember, contaminants such as moisture in the supply air can elevate temperatures and otherwise accelerate the oxidation process.
TGA analysis is a technique in which the mass of a substance is monitored as a function of temperature or time as the sample specimen is subjected to a controlled temperature program in a controlled atmosphere. A careful TGA can help chemists understand how a specific antioxidant and synthetic base fluid combination will perform in a formulation throughout a range of temperatures. For instance, a formulation can often include both primary and secondary antioxidants. Understanding the thermogravimetric curves allows the lubricant chemist to engineer the best possible thermal oxidation profile for a given formulation, thereby promoting longer lubrication life.
Stay Involved in Preventive Maintenance Program
Compressed air is critical to your food and beverage operation. Some may argue it’s as vital as electricity, water, and natural gas. Unfortunately, it requires as much or more care and attention than the utilities you rely upon.
Maintenance professionals understand the benefits of preventive air compressor maintenance programs – reduced downtime, cost savings on emergency repairs, longer air compressor life, and lower energy costs because the system runs more efficiently.
Many air compressor distributors offer preventive maintenance programs. Outsourcing these programs to your local distributor make perfect sense. They address consumables and wear items such as air and oil filters, motor bearings, and belts. Inspecting system components and performance add a predictive component to the maintenance program. Regular inspections for air leaks, elevated operating temperatures and increased vibration can all indicate potential emerging problems and allow them to be corrected before incurring costly downtime and emergency repairs.
Of vital importance to the overall health of your compressed air system is the lubricant used and how often it is changed. Certainly, any compressed air maintenance system will include changing the lubricant at a specified time period. Oftentimes, the lubricant is simply replaced with the air compressor manufacturer’s branded air compressor lubricant. Furthermore, the time period used is the standard lubricant change interval identified in the air compressor operator’s manual. While these are great places to start, both the lubricant and change intervals should be tailored to your unique circumstances.
For instance, if your source air is contaminated, or contains high moisture content, you may very well experience accelerated oxidation cycles. In that case, you would want to ensure that the lubricant used in your compressed air system is of a formulation that has an excellent viscosity control and exceptional thermal oxidation stability. Your air compressor manufacturer likely offers the right formulation for your needs, but it’s your responsibility to understand what’s being used in your system. It’s your equipment ROI, your efficiency, your maintenance costs and potentially your brand that are on the line.
While the manufacturers’ standard oil change intervals are a great place to start, they should not be treated as a given. Rather, the change interval should be determined by a number of programmatic observations, including regular used oil analysis. Staying involved in the preventive maintenance program is important.
A thorough analysis program of oil used in air compressors offers multiple benefits for food and beverage operations.
Important Oil Analysis Parameters
An effective analysis program for oil used in your facility’s air compressors should focus on a few key parameters. Source air aside, the following analysis parameters are of particular interest for food-grade compressed air lubricants:
- pH – A rapid or excessive decrease in pH indicates ingestion of acid gases or other contaminants from the environment. This will not only require a fluid change, but will also require that the source of the contamination be eliminated to rectify the condition.
- AN – The acid number is an indication of remaining useful fluid life. Oxidative degradation of the lubricant or an accumulation of contaminants from the environment can trigger an increase in AN. Regardless, accumulated acid is reflective of a depletion of the corrosion inhibition package.
- Contaminants – Hydrocarbon contamination is typically monitored to assure that operators are not mixing fluid types. Mixing fluid types can compromise fluid life.
- Oxidation – Synthetic fluid changeout intervals can be determined by the degree of oxidation of the base fluid by using FTIR infrared spectroscopy.
- Viscosity – The viscosity of some OEM compressor fluids is specifically engineered for the needs of the air compressor and do not fit into either the ISO 32 or 46 viscosity ranges. Therefore, it is always important to compare viscosity to the specification for that fluid, rather than an ISO range.
A thorough analysis program of oil used in the air compressors has analytic benefits beyond just the air compressor fluid as well. It can also help identify other system concerns by identifying any particulates found in the used lubricant. For instance, analytical ferrography can be used to identify the source of the particulates, such as wear debris from bearings and rotors, contamination from inlet air, or corrosion particles from the tank.
Take Ownership in Maintenance of Compressed Air Systems
The bottom line is the bottom line. Staying actively involved in the maintenance of your compressed air system and having a basic understanding of the chemistry and capabilities of your air compressor fluids ensures that the program is optimized to help your food and beverage facility meet your safety, operational and financial goals.
About the Author
Jim Cross is Marketing Director with JAX INC., tel: 800-782-8850, email: email@example.com.
About JAX INC.
JAX INC. is a U.S.-based industrial lubricant manufacturer with expertise formulating high-performance synthetic lubricants, fleet and heavy-duty lubricants, industrial lubricants and biodegradable and food-grade lubricants. Since 1955, JAX has earned a worldwide reputation as a leader in emergent lubrication technology. For more information, visit www.jax.com.
All photos courtesy of JAX INC.
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