Preventive Maintenance Prolongs the Life of Oil-Free Compressors

One of the reasons manufacturers are turning to oil-free air compressors is that they require minimal maintenance; however, it’s important to remember that they are not entirely maintenance-free. As a matter of fact, preventive maintenance on oil-free air compressors is necessary to ensure that the unit remains operational for years to come. Here, we suggest eight preventive maintenance activities that should be performed on a regular basis.

What is an Oil-free Air Compressor?

Oil-free air compressors do not use any oil within the compression chamber. Instead, some versions of this specialized air compressor type use alternative materials such as water or Teflon to protect components while allowing them to move smoothly without the use of oil-based or synthetic lubricants. Other oil-free compressor designs have completely removed metal-to-metal contact from the compression chamber, eliminating the need for any lubrication at all. It should be noted that in some oil-free models, the bearings and gears within the gearbox will still require lubrication; however, this is external to the compression chamber and proper sealing of the gearbox ensures that oil will not contaminate the delivered compressed air.

Oil-free air compressors are especially important in industries such as food, beverage, pharmaceuticals, electronics, and other industries where preventing oil contamination from damaging a finished product is crucial, as oil-free compressors significantly reduce the number of contaminants in the air supply.

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Preventive Maintenance Requirements

It’s important to note that while the maintenance needs are fewer in oil-free compressors, the design and lack of lubrication means that there is nothing to take away the heat generated by the motion of the compressor’s operation (lubricants in traditional compressors also serve as coolants to reduce this heat load), so thermal expansion can be an issue. It’s also important to note that any gearbox and driving engine will still require lubrication.

In addition to keeping heat load and gearbox/engine lubrication tasks at the front of mind, there are several preventive maintenance activities that should be performed on a routine basis to ensure safe and efficient operation and prolong the life of an oil-free compressor, including:

  • Evaluate Air Filters: As air enters the compression chamber, the air intake filter catches any contaminants that could damage the cylinder. Just like in a traditional air compressor, the air intake filters should be checked on a regular basis to ensure that they are not clogged, as dirty filters will compromise the effectiveness and efficiency of the air compression system. Clean filters will also help prevent excessive temperatures.
  • Check and Replace Seals as Needed: Properly functioning seals are imperative in oil-free air compressors as they are needed to keep oil from entering the compression chamber; however, due to issues with thermal expansion in oil-free compressors, seals may experience more frequent wear. In oil-free compressors, seals will need replacement, usually between 2,000 and 8,000 hours of operation, depending upon how the equipment is used and the design and type of sealing material. Since seal replacement can take the compressor down for several hours, it’s best to replace seals during a planned outage and before the seals have deteriorated to the point where the compressor loses functionality.
  • Test the Air Compressor Safety Valve: As this is a safety component, the safety valve should be checked on a regular basis. While wearing safety glasses, plug the unit in, allow it to run until it reaches its shut-off pressure, and pull out the safety valve ring so the pressure is released from the tank. If it does not close automatically or the air release does not occur, it’s time to replace the valve.
  • Keep Pressure Under Control: Maintaining proper pressure ensures safe and efficient operation of an oil-free air compressor, so it’s important to check the pressure when the unit is operating and to do so on a regular basis. If pressure is higher than is recommended for your oil-free air compressor, take action to reduce it to the proper level as running at high pressures can negatively impact the lifespan of the compressor and result in unnecessary energy usage.
  • Find and Fix Leaks: As with any compressor, it’s important to ensure that there are no leaks when the compressor is running, as well as when it is turned off. Leaks lead to low system pressure, can impact the function of the equipment the compressor powers and are the leading cause of energy losses in compressed air systems.
  • Drain the Air Compressor Tank: As moisture is squeezed from the compressed air, it will fill the receiver tank and lead to a reduction in the amount of air the receiver can store. If the air compressor tank is not drained on a regular basis (check the manual as some recommend draining weekly or at other intervals), accumulated moisture will result in corrosion of the receiver tank and may lead to air contamination, which will eventually damage the compressor and other system components and/or product quality.
  • Inspect the Power Lead: Examine the power cables for damage from wear and tear. A damaged cable can result in the unit pulling more power to run the compressor, causing heat to build up in the cable, the starter, and the main motor, which will result in the failure of the compressor. If damage is found, stop using the compressor immediately and have an electrician repair the damaged power lead to ensure safe operation.
  • Perform Visual Inspections: Regularly inspect components such as hoses, valves and seals to find cracks or other signs of wear and tear and ensure that fittings are secure. If damage is noted, it should be attended to as soon as possible to prevent problems from becoming more serious and more costly and to avoid pressure drops and wasted energy.

While oil-free air compressors require significantly less maintenance than their traditional, oil-lubricated cousins, they do still need preventive maintenance attention such as cleaning air intake filters and visual inspections of seals, hoses, fittings, power cables and other small preventive maintenance tasks to ensure effective and efficient operation, as well as high air quality and a long lifespan of incident-free functionality.

For more information on these and other maintenance activities for oil-free air compressors or to see if one is right for your facility, please contact John Henry Foster.