Rotary Screw Air Compressor Maintenance Guide

The versatility and ease of use make the rotary screw air compressor a top choice for operations of all sizes, from the largest of manufacturers to private, one-person operations. When well-maintained, a rotary air compressor can perform for thousands of hours.

Why Regular Rotary Screw Air Compressor Maintenance Is Important

Like all compressor types, rotary screw models do require periodic maintenance. Thanks to the simplicity of the internal components, maintenance is relatively easy on most units. As long as you stick to a rotary screw air compressor maintenance schedule, you will likely be rewarded with many, many years of optimal performance.

Rotary Screw Air Compressor Maintenance

1. Save Time and Money
A regular rotary screw air compressor maintenance schedule reduces the risk of downtime at unexpected intervals because you can spot potential problems when they arise – before they get out of hand and grow into more serious issues. The earlier you identify a problem, the easier and less costly it is to remedy. In many cases, a problem detected early can be rectified in a few minutes, at no cost.

Routine maintenance also saves time in the long run. As you know, system downtime is costly and time-consuming. With regular rotary screw air compressor maintenance, you lower the risk of costly downtime.

2. Prevent Emergency Repairs
One of the biggest risks of an irregular rotary screw air compressor maintenance schedule is the chance of sudden, unexpected emergencies. If you only inspect your compressor on occasional, irregular intervals, you are not keeping track of how it performs on the inside. Even if the compressor seems fine on the outside and was purchased within the past few years, there could still be internal issues  that you’re liable to miss if you only perform inspections on an infrequent, irregular basis.

In a worst case scenario, your compressor might stop functioning for reasons that could be hard to pinpoint. Consequently, a diagnosis could be even more time-consuming and costly. With consistent, periodic maintenance, you can pinpoint issues early and have them remedied almost immediately.

3. Improve Your Compressor’s Life Expectancy
Over the years that you use the machine, you could ultimately get a better return on your initial investment by inspecting the compressor on a regular basis. As with any motorized machine, an air compressor will generally last longer when it’s well-maintained and inspected on schedule.

Routine maintenance can also help you turn your initial investment into an enormous return. If and when the time comes that you finally replace the machine with a newer model, the old compressor will have likely yielded a fortune regarding productivity.

A Guide to Rotary Screw Air Compressor Maintenance Tasks

A quality rotary screw air compressor is built to last through many years of heavy-duty operation. That said, air compressors do have their limits and need to be inspected on a periodic basis to ensure optimal performance for the duration of their life expectancy.

A rotary air compressor consists of several key internal components that could wear down over time if you don’t give them due, timely inspections. Chief among these parts are the airend and the drive train, which respectively pressurize the air and drive the mechanisms of the air compressor. It is also important to inspect the motor and filters on a periodic basis and replace the lubricants when necessary.

Airends
Of all the components that comprise a rotary screw air compressor, the airend is the most crucial because this is where the air pressurization takes place. While an airend can generally last for at least 40,000 hours, it can malfunction before its time if not properly maintained. An airend can be damaged by extreme system heat, dirty fluid and contamination.

To prevent the development of damaging conditions, you must inspect the airend on a periodic basis. Check for the following issues during each inspection of the airend in your rotary screw air compressor:

  • Overheating: While the airend is built to withstand its share of heat, system issues can push the temperature to far. Monitor the air compressor’s heat level on a regular basis to ensure that the internal components are not fielding too much heat.
  • Improper lubrication: As with any moving part, an airend can wear down without sufficient lubrication. Friction between poorly lubricated metal parts can generate excess heat and set off a chain of problems.
  • Corrosion: If corrosion or rust develop on the airend or any adjacent component, it’s a clear sign that the machine has not been sufficiently maintained, lubricated and drained. Corrosion forms when the surfaces of metal parts absorb moisture or face internalized friction due to inadequate lubrication.
  • Incorrect control adjustment: In some cases, an airend will wear out at an accelerated pace due to improper settings. Operators who oversee this area should understand the proper settings and monitor them on a daily basis.
  • Over-pressure: If the air compressor exerts too much pressure to operate at regular levels, the parts within have lost their ability to function normally. An airend could be forced to overexert itself if the machine grinds and overheats due to lack of lubricants.
  • Condensation: If you don’t drain the air compressor drip tray on a daily basis, condensation can occur and cause system problems. Condensation can also be an issue if the air compressor lacks sufficient ventilation, especially if operated in subzero or humid conditions.
  • Vibrations: If an air compressor makes unusual vibrations, the internal parts are probably enduring excess strain. Strange vibrations should serve as a red flag that the compressor needs to be shut off and inspected for airend issues as soon as possible.
  • Bearing noise: Just as with vibrations, strange and unusual noises from an air compressor should serve as a red flag that something is wrong. In a rotary screw air compressor, an unusual noise will typically be the result of worn airend bearings. Pay close attention to oil leaks and strange noises from the motor bearings as these are the two main indicators of imminent problems with an air compressor.
  • Oil seal leaks: If the oil leaks, the air compressor will be drained of the fluid that the mechanisms need to operate properly. Oil leaks result in more than just wasteful fuel consumption as they lead to mechanical friction and system overheating. If you spot an oil leak, shut off the compressor and inspect the issue immediately.

Drive Train
In a rotary screw air compressor, the drive train guides the motion of the internal mechanisms as a whole. Therefore, the drive train must have correct alignment at all times for the air compressor to function properly. The gear drives must be freshly lubricated on periodically to ensure smooth running at all times. When you inspect the drive train, check for the following symptoms:

  • Poor alignment: If the drive train is out of alignment, it won’t be capable of driving the motions of the air compressor with proper consistency. A poorly aligned drive train can cause system stress that could lead to premature failure of the motor bearings. An ill-aligned drive train can also take its toll on the airend.
  • Worn belt: For the drive train to move at a proper pace, the belt must be working properly. If the belt becomes worn or frayed, it won’t have sufficient tension. Each time you inspect the belt tension, check for frayed ends and cracks.
  • Improper belt tension: If the belt tension is off, the machine will work overtime to maintain an even pace. Ideally, the tension of the belt should be inspected every 500 hours and adjusted if necessary.
  • Insufficient lubrication: Lubrication makes internal mechanisms turn with smoothness and consistency. If the lubricants are old or spoiled, the drive train is liable to be a source of friction within the compressor.

Overall, the drive train should be inspected every other month to ensure that the belt remains intact and properly adjusted and that the lubricant maintains proper viscosity.

Motor
A healthy motor requires an operating area that is sufficiently ventilated while in use. To prevent overloading, keep track of the ampere draw. Most importantly, make sure that the motor bearings are properly lubricated during each inspection. Some of the biggest problems with rotary air compressor motors result from the following problems:

  • Insufficient grease: If grease is inadequately applied to the bearings, the motor is deprived of necessary lubrication. This can lead to friction between metal parts that will cause the system to overwork and generate excess heat.
  • Hardened grease: In colder working environments, grease can harden and lose its viscosity. In worst-case scenarios, grease can freeze in subzero temperatures and become sludgy when temperatures rise back to normal.
  • Melted grease: In hot working environments, grease can lose its viscosity in the opposite way and become a runny and ineffective lubricant. Under intense heat, grease can melt away and leave the metal parts of the motor unprotected.
  • Over-greased parts: If the bearings of the motor are over-greased they could become  incapable of moving properly because the grease would function more as a coat of molasses than an actual lubricant. To keep your bearings running smoothly, make sure that fresh applications of lubricant don’t go below or above the recommended amount.
  • Mixed greases: Greases are not made to be mixed together. When you apply a new coat of grease, remnants of the last application of grease should be wiped away first. The old grease could have acidic elements that might contaminate the new grease and ruin its effectiveness.
  • Wrong grease: If you lubricate your air compressor with the wrong grease, it won’t offer the necessary protection against internalized mechanical friction, especially not under extreme temperatures.

Without the right grade of grease in proper proportions, the metal bearings of a rotary compressor are left to grind against one another with every revolution of the motor.

Filters
In addition to the air/oil separator, a rotary screw air compressor contains two other filters — the oil filter and the inlet filter. Each of these filters must be inspected regularly to ensure optimal filtration and to prevent the spread of dirt and oily mist throughout the system. Ideally, you should check the inlet filters after every 2,000 hours of operation. You should inspect the fluid filters every 1,000 hours. Filter maintenance helps to spare the system of the following problems:

  • Airend wear: The dirt from a clogged filter can pass through an air compressor and diminish the quality of the pressurized air. A dirty filter also deprives the system of proper ventilation.
  • Oil contamination: Poor filtration can dirty up the oil and grease within an air compressor, reducing the quality of lubrication and rendering the system more vulnerable to breakdowns.
  • Reduced air quality: Poor filtration has a detrimental effect on the quality of end-point applications because the outbound pressurized air is dusty, oily and watery.
  • Component contamination: As unfiltered dirt and oil spread to other parts of the air compressor, problems are liable to ensue with different components as dust collects on oily and moisture-laden surfaces.
  • System overheating: When an air compressor lacks sufficient inlet filtration, system overheating could occur due to accumulation of air-bound particles. The hotter the mechanisms become, the shorter the service life between each round of maintenance.

When the filters accumulate dirt, an air compressor could lose its ability to function properly.

Lubricants
The oil supply is vital to the health of a rotary screw air compressor. Oil allows for clean and easy movement between the various parts that drive the pressurization of incoming air, and it keeps the air compressor cool through many hours of heavy-duty operation.

To do its job properly, you must change the oil on a regular basis. Sample the oil every two or three months to ensure that it retains the right color and consistency. Once the level drops, clean out the old oil and refill. Never mix old and new oils because the former could have contaminants that would infect subsequent oil supplies. Overall, you must prevent the following conditions from taking hold of the oil in your air compressor:

  • Leaky oil: An oil leak could be indicative of a crack in the oil compartment or an ill-fitted connecting fastener.
  • Acidic or contaminated oil: Stale oil is liable to develop acidic qualities, especially if it comes into contact with moisture, dirt or rust.
  • Mixed oil: The oil in your air compressor must remain clean and pure. When mixed with other grades or with older, contaminated oil, it could have ill-effects on your system’s health.
  • Diluted oil: In a dirty air compressor, oil can come into contact with stray elements and become contaminated. If your system is plagued with stray dirt and dust due to poor filtration, the dirt could corrupt the oil. The same holds true if the drainage is inadequate and the oil becomes contaminated with watery mist.
  • Improper oil: If the oil in your air compressor is a different grade than the kind recommended in the user’s manual, it could cause problems due to improper lubrication. For air compressors, specific oil grades are recommended for a reason.
  • Runny oil: If the oil in your air compressor loses its viscosity, it is no longer as effective as it should be. Runny oil is about as effective as water when it comes to lubricating parts.

Oils can last anywhere from 3,000 to 8,000 hours, but this depends on the type of operation in question. To know what kind of oil is best for the make and model of your air compressor, consult the user’s manual or contact the manufacturer.

How Often Should Rotary Screw Air Compressor Maintenance Be Performed?

Over the course of 3,000 hours of use, changes are liable to occur within the compressor that can alter certain settings, negatively impacting the health of your system.

Rotary Screw Air Compressor Maintenance

Daily Rotary Screw Air Compressor Maintenance
At the end of each work day, check the control panel displays on your air compressor to ensure that the readings are normal. Also make sure that the gauges are properly set according to the specifications of your make and model. As a guide for these inspections, compare the records of previous days and months to ensure that the measurements remain consistent over time.

Perform these observations for each mode of operation, regardless of whether or not you run the machine at full load. If the readings begin to deviate from the records, despite a lack of adjustments, it’s time to inspect your air compressor.

Quarterly and Biannual Rotary Screw Air Compressor Maintenance
After every 1,000 to 3,000 hours of operation, your air compressor’s filters should be inspected and serviced as necessary. For best results, stick to the screw compressor maintenance checklist included in your instruction manual. Intervals vary greatly from unit to unit:

  • Daily Inspections
  • Quarterly Service
  • Annual Service
  • Major Overhaul

On a weekly basis, inspect the condensate drain and clean if necessary. Also take record of the readings on the compressor, motor and gearbox. Refer back to the user’s manual of your air compressor to ensure that the settings and readings remain consistent with the recommendations of the manufacturer.

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Questions? Contact us for more information and advice on maintaining your compressed air system. Michigan Air Solutions is a reliable source for helpful compressor maintenance information. We also offer a wide selection Quincy air dryer systems. Our customers are located in Grand Rapids, Detroit, Lansing, and everywhere in between.