Rotary Air Compressor

Rotary Air Compressors in Your Automotive Shop May be Costing You Money

There has been a trend in recent years to promote the use of rotary compressed air in automotive care applications because reciprocating technology is perceived as “dated” and rotary as “cutting edge.” Rotary technology is also much quieter than Recip technology, which increases the perceived value of rotary machines. It’s true that rotary technology is newer and quieter than Recip, however, the initial cost for a rotary machine is typically 50% more than an Ultra Pack Recip machine, regardless of whether it’s right for the job or not. In addition, there are several hidden costs associated with rotary machines that need to be considered before deciding which one is the best fit for your application:

Maintenance Costs – Some manufacturers have mistakenly led customers to believe that Recip machines are more expensive to maintain than rotary machines by stating that there is “easier” or “less” maintenance involved in a rotary compressor.  While it is true that rotary maintenance intervals (typically 2000 hours or one year, whichever comes first) are longer than recip maintenance intervals (typically 3 or 6 months), the cost of the consumables makes rotary maintenance 2 to 3 times that of recip over a 5-year period.

Misapplications – One of the great advantages of rotary technology is that it loves to run all the time. So, if you have an application requiring a continuous use of air, and you size the compressor appropriately, a rotary machine will perform well without overheating. But, this strength becomes a weakness if a rotary machine is misapplied.

Intermittent demand – If a rotary machine is placed in an application where demand fluctuates greatly, it will be underutilized during periods of low demand. This will cause the rotary machine to “short cycle” – i.e., the machine will not run long enough to build up the temperatures required in the airend to burn off water vapor in the oil. When a machine short cycles, it can lead to premature fouling of internal filtration and downstream components; to pre-mature airend failure; and potentially to motor failure, if an electronic controller or timer is not used to ensure that the machine does not start and stop too often. All these potential issues add up to extra maintenance and/or replacement costs for misapplied rotaries. In addition, these things may void a manufacturer’s warranty, leaving the end-user to bear the burden of all costs.

Importance of sizing – If a rotary machine is oversized to account for future growth or simply as an insurance policy to make sure enough air is supplied to a customer, all the issues outlined above come into play.  An oversized machine will almost surely short-cycle and lead to increased maintenance and service issues.

Cost of extra tank if flexibility is needed – If a rotary machine is misapplied, one of the ways to fix the application is to provide a larger storage buffer by adding a remote stand-alone tank, which will cause the compressor to run longer and achieve the required operating temperature.  While this can be an effective solution, it adds extra cost to some rotary applications that should be considered up front.

Bleeding air to the atmosphere – Another solution to short-cycling is to bleed air to the atmosphere if there is not enough demand.  This requires extra equipment and means that the customer is spending money to compress air that is literally vented into the air instead of being put to work in the shop. Although this can be an effective solution, it again adds costs that should be considered up-front.

Re-builds – While rotary airends typically are designed to last twice as long as the best recip pumps, it costs a great deal to have them repaired or re-built, and in some cases, it is not possible to do so. So, if a rotary machine is misapplied and the airend fails prematurely, the cost of the re-build will dwarf the cost of re-building a piston compressor.Automotive shop air compressor

While rotary machines are great in many applications, it pays to do some homework upfront to make sure a rotary makes sense in your application. At a minimum, check the following before buying a rotary machine for your shop:

  1. Make sure it’s the right size – A walk-through assessment of your shop is the best way to tell what size you need. If that option isn’t available, a simple pump-up test may suffice. If math is not your strong suit and you don’t have access to assessment equipment, work with a local air compressor expert to determine what is the appropriate size.
  2. Make sure your demand profile is appropriate – Basically this means ensuring that air demand is consistent enough to warrant a rotary machine. Again, a walk-through assessment is a great way to determine this but engaging a local air expert is a good backup.
  3. And finally, once you buy the machine, make sure that it’s installed and maintained on a regular basis by a qualified rotary screw service center.

Rotary or Recip? The choice is yours. But an educated decision could save you some money. Learn more about what compressor you need for your automotive shop.

Ask an Expert

Have a question or a topic about air compressors that you would want answered? Want to give some feedback? Ask one of our experts.

Fill out the form below to submit your comments to our experts. If we choose your question to be published on our website we will send you an exclusive FS-Curtis gift. So get in your questions so we can make your air compressor experience that much better.

If you have an FS-Curtis product and need help troubleshooting your equipment or if you need a service, you can get in touch with your local distributors.


Stable Air Pressure and Why It’s Important

Understanding stable air pressure is simplier that you think. For most people compressed air is like electricity in that they do not think about it until they don’t have it. For example, most people would never stop to think about the pressure fluctuations in their compressed air system. Likely, the only time this becomes an issue is when an operator squeezes his air gun and the hissing sound isn’t loud enough which indicates that the tool will not be able to turn the bolt. In this case, the most common answer is to go to your favorite store and buy another air compressor.

Why should anyone care about how much the pressure swings in their piping and tank system? As we will see it’s all about saving money and increasing reliability.

It’s important to understand that everyone thinks that they have stable air pressure that does not fluctuate. However, if you do not have a flow control device, such as the DemandSmart Flow Controller, then you can be assured of these facts:

  • The air pressure that your compressor must produce is higher than necessary
  • It is fluctuating at least 10 psi. Even if you have a regulator it will still “track” with system pressure. That means if your regulator is set to 90 psi and the upstream air pressure fluctuates between say 125 and 135, then the regulator will also fluctuate between 90 and 100 psi
  • The all-important question is how does stabilizing the pressure to say 1 or 2 psi (versus 10 psi) save money and increase reliability?
  • Less air is lost by leaks and therefore the compressor can be “off” for longer and not consuming electricity
  • The compressor does not have to make as high a pressure. A good rule of thumb is that for every 2 psi drop in pressure that the compressor must make results in a 1% decrease in energy
  • Air tools are designed to work at very specific pressures so if this is stable then they last longer because the air pressure is at their ideal operating parameters. Air tools that last longer and operate at premium efficiency cut down on maintenance cost and prevents work stoppages
  • Air compressors will last a lot longer. This is because the compressor controls do not have to directly respond to users of the air. For example, with no flow control device, the compressor must load or unload as an operator blasts his air gun. With a flow controller, the valve will use the air in the tank and piping system to supply the operators demand. The valve cannot “produce” air so the benefit to the compressor is longer on and longer off time which saves wear and tear on valves and components

With all these savings combined, it is very typical to have a payback in less than a year. The best proof for the importance of stable air is to ask anyone using a flow controller if they would get rid of them…. Most compressed air users would not.

Nx Series…The Best in Rotary Screw Air Compression

The Nx Series offers a space-saving profile that’s easy to install while accommodating limited floor space. The integrated separator, MPV and thermostatic valve reduce connections by up to 90% -- meaning fewer opportunities for leaks. The Nx series also comes in variable speed drive for 8-90kw for even more efficiency and energy savings opportunities. The FS Curtis Nx SERIES combines efficient operations with outstanding durability.. The perfect combination for automotive, light industrial, and other applications that require reliable performance in demanding conditions.

Learn more about this Plant Engineering 2015 & 2016 Product of the Year

FS-Curtis…Our Reputation Has Stayed The Same

For over 160 years FS-Curtis has prided itself on being the best in air compression. Assembled in St. Louis, MO we are proud that our reputation for having quality products and great customer service has continued to be unwavering. Our Reputation Has Stayed The Same...


How Can an Air Audit Maximize My Savings?

An air audit may be in order for your compressor system, especially if it hasn’t been carefully examined recently. While many people focus on the initial cost of purchasing an air compressor, they often forget to factor in the cost of operating the machine over the long run. Any issue within a system can reduce its efficiency, wasting air and electricity, and thereby costing you more money.

A compressed air audit, done by qualified professionals, will indicate the opportunities an organization has to increase efficiency and save money on energy costs by examining the air supply and demand. According to the U.S. Department of Energy, on average up to 50% of the energy it takes to run one 100hp air compressor is wasted.


But what exactly can an Air Audit do for you? Learn more about how you can help you maximize savings. Download "What is a Compressed Air Audit"?

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How to Reduce Your Compressed Energy Costs

Compressed air can be one of the most expensive forms of energy for manufacturing plants, often using more energy than other equipment. One horsepower of compressed air requires eight horsepower of electricity. With many air compressors running at efficiencies as low as 10 percent, there’s often plenty of room for improvement. Fortunately, 50% of compressed air systems at small- to medium-sized industrial facilities have opportunities for low-cost compressed energy conservation.

Learn how you can save money and keep your air compression working at a premium by downloading our "10 Ways You Can Optimize Your Air Compression and Save Money".



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What Is A Compressed Air Audit?

An air audit may be in order for your compressed air system, especially if it hasn’t been carefully examined recently. While many people focus on the initial cost of purchasing an air compressor, they often forget to factor in the cost of operating the machine over the long run. Any issue within a system can reduce its efficiency, wasting air and electricity, and thereby costing you more money.

But what exactly can an Air Audit do for you? Learn more about how an Air Audit can help you maximize savings. Download "What is a Compressed Air Audit"?


FS-Curtis and the Fabricated Metals Industry

Compressed Air is an integral part of the Fabricated Metals Industry. Premier Tool Grinding manufacturer of carbide cutting tools uses our NxB22 along with our RNE Dryer and CF Filtration system. See how we assist companies like Premier Tool in the Fabricated Metals Industry.
Many processes and applications continue to use inefficient devices to deliver the compressed air, and many companies fail to recognize the simple implementation and significant payoff of improving compressed air efficiency.

Improving compressed air efficiency, or saving more of your compressed air capacity by minimizing compressed air demand, can be realized by following some simple procedures. Though there are many actions that can be taken to further improve compressed air efficiency, some simple and effective steps can be put to action quickly.

A few things you need to do to improve the demand of your air compression: Measure the air consumption to identify sources that waste compressed air Find and fix the leaks in your compressed air system. Upgrade your blow off, cooling and drying operations using engineered compressed air products. Use intermediate storage of compressed air near the point of use Control the operating air pressure at the point of use to minimize air consumption.

Why not take your compressed air to the next level by seeing the services and products that FS-Curtis can offer?


Pros and Cons of Individual Compressor Controls

Previously we described the 6 different types of Basic Air Compressor Controls but what kind of control would you want for your compressor. Her are few pros and cons of the controls to help you assess the needs of your compressor.



  • Simple control using only a pressure switch
  • Motor and compressor operate only when needed which saves energy
  • Good for small compressors that are 25 HP or less (depending on application)


  • Frequent starting wears down motor and compressor
  • Pressure setting to stop must be higher than required system pressure to build storage and may increase energy use
  • Loses of pressure control in the range of 35 psi
  • Limited to small compressors



  • Motor compressor runs continuously which reduces wear  and tear associated with too many frequent motor starts
  • Tighter range of pressure (approx 10 psi)
  • Provides adequate storage and offers energy-efficient control of rotary screw, reciprocating and some centrifugal compressors


  • If applied incorrectly short cycles cause  premature wear and tear. There is minimal or no power savings on lubricant-injected rotary screw compressors
  • There needs to be proper blow down time and the storage capacity required for lubricant-injected rotary compressors to achieve energy savings and prevent lubricant foaming
  • Requires over-pressurizing to maintain minimum system pressure



  • The motor and compressor run continuously reducing wear
  • Tighter range of pressure control (10 PSI)
  • Steady progressive capacity control that matches demand


  • Pressure ratios increase as inlet pressure is throttled
  • Inefficient at lower loads(lubricant-injected rotary compressors limited to 40-60% capacity; centrifugal compressors limited by potential surge and may require discharge blow off)

Dual/Auto Dual


  • Combines features of modulating, load/unload. and start/stop
  • Shuts down compressors when unloaded for pre-set duration which in turn saves energy
  • Better selects operation mode for small reciprocating compressors


  • Makes the control complex
  • The Over-run timer must be set to limit premature starting and stopping

Variable Displacement


  • Energy-efficient control scheme that gets down to 50% of capacity
  • Matches displacement to demand without reducing inlet pressure or increasing ratios of compression


  • Makes the control complex
  • High initial cost
  • Only available for 50 HP+ compressors

Variable Speed


  • Energy-efficient and precise control
  • Various rotating speeds and giving more displacement and power. These are directly proportional to speed rotation


  • Makes the control complex
  • High initial cost
  • Reduced full load efficiency
  • Efficiency of rotary screw compressor ends drop at lower or higher speeds

The 6 Types of Basic Individual Compressor Controls

Compressor controls are designed to match compressor delivery with compressed air demand, by maintaining the compressor discharge pressure within a highly specified range.  This discharge pressure should be set as low as possible to minimize the energy usage.

Compressor systems are typically composed of multiple compressors delivering air to a common plant air header. The combined capacity of these machines is generally sized to meet the maximum plant air demand. System controls are almost always needed to orchestrate a reduction in the output of the individual compressors during the times of having lower demand. Compressed air systems are usually designed to operate within a fixed pressure range and to deliver a volume of air that varies with system demand. System pressure is monitored and the control system decreases compressor output when the pressure reaches a predetermined level. Compressor output is then increased again when the pressure drops to a lower predetermined level.

There are 6 basic types of individual compressor controls that a person has to take into account when looking into purchasing and using air compression:


  • Turns the motor which drives the compressor on or off in response to a pressure signal (seen on reciprocating and rotary compressors)


  • Allows the motor to run constantly but unloads the compressor when a predetermined pressure is reached. The compressor reloads at a predetermined lower discharge pressure. This is also sometimes referred to as constant speed or constant run control (seen on reciprocating, rotary, and centrifugal compressors).


  • Restricts passage of air to the compressor to progressively reduce compressor output to a specified minimum, when the compressor is then unloaded. This is also referred to as throttling or capacity control (seen on rotary and centrifugal compressors).

Dual/Auto Dual

  • This controller is commonly seen in small reciprocating compressors, allows the selection of either Start/Stop or Load/Unload. When used in a lubricant-injected rotary compressor it provides modulation or load/unload control to a preset reduced capacity. When unloading the addition of an over-run timer will stop the compressor after running unloaded for a preset time.

Variable Displacement

  • This controller allows progressive reduction of the compressor displacement without reducing the channel opening (seen on reciprocating and rotary compressors).

Variable Speed

  • This controller adjusts the compressor capacity by varying the speed of the electric motor driving the compressor in response to system signals.

Learn more about the these six basic compressor controllers and more about other FS Curtis products

4 Ways to Get Efficient Rotary Air for the Summer

4 Ways to Get High Level Rotary Air Compression for the Summer

With high summer temperatures fast approaching please make sure your Rotary Compressor is prepared for the change in climate. Here are 4 tips to keep your Rotary Compression at peak performance for the summer.

  1. Lubricant and Coolant Levels

Is your lubricant and coolant low? Is it due for a fluid and filters service? Please note that running FS-Curtis synthetic fluids will reduce the heat generated by your compressor. The compressor oil serves as coolant in oil flooded rotary compressors. In rotary compressors, the compressor oil is circulated 7 or more times per minute through the machine. This is why oil levels become more critical in the summer. To be sure of the condition of your air end and bearings we recommend an oil analysis by any of one of distributors.

  1. Air Density

In the summer your compressor will have a lower performance. Make sure you install a new intake filter for the hot summer days. Please be aware that dirtier environments require more frequent intake air filter changes.

  1. Having Clean Compressor Air and Oil Coolers

A clean cooler may be the difference between normal operation and a high temperature shut down. Many times synthetic compressor oils are fruitless because the oil breaks down prematurely due to overheating. To protect from high acid numbers, loss of lubricity and increased viscosity, long oil change intervals must be monitored with frequent lube analysis, particularly when exposed to high ambient temperatures. Please contact your local FS-Curtis service company for a compressor “health” check.

  1. Hot Ambient Air and Moisture

Most lubricated, air cooled, rotary screw compressors run 100 to 110 degrees F above the ambient temperature. If your compressor room is over 100 degrees, you are already in trouble. Cross flow ventilation is advisable in non ducted compressors. If your compressor oil sump or airend discharge is more than 120 degrees F over ambient temperature in the room, you need to find out why. FS Curtis has factory approved Air Treatment accessories to minimize moisture in your system and water in the air lines.

What To Consider When Purchasing a Rotary Air Compressor?

What do you Consider when purchasing a rotary air compressor? Let’s say you buy a Volvo, arguably considered one of the safest cars on the road, and you drive it 70 mph into a brick wall (by the way, don’t do this, it ruins the paint job), is it the car’s fault that it may no longer run?

The same scenario applies to equipment. If the OEMs installation recommendations are not adhered to, there will be a high degree of probability that the compressed air equipment will not be reliable, will not experience the stated longevity, may require above average maintenance, may consume more electrical energy than required and may not consistently provide the compressed air quality required by production.

While it’s impossible to cover all of the things you need to consider when installing a rotary air compressor (and we hope it’s an FS-Curtis), this short article is intended to help avoid the equivalent of driving your car into a brick wall.


1) Have your system voltage measured. The most common electrical utility voltages in the United States are 200 volt, 208 volt, 230 volt, 460 volt. Electrical utilities guarantee a voltage supply tolerance of + 10%.  For example, if the voltage stated supply is 230 volts it could measure at any given time from 207 up to 243 volts. Most electrical utilities attempt to hold the supply voltage to + 5%. Operating electrical motors off design or away from their nameplate voltage will generate additional heat leading to reduced motor life expectancy. The majority of induction motors, 5 hp through 600 hp supplied to the U.S. market, are 230 & 460 volts; however, 200 & 208 volt systems are becoming more popular. If a 230 volt name plated motor is operated on a 200 to 208 volt system it will operate in an elevated heated condition leading to extremely reduced motor life. This is not a recommended practice. There are motors specifically designed for 200 & 208 volt operation. For these applications motors name plated as such should be used.

2) Many air compressors operate into the motor service factor. As such, request the package full load operating amp draw from the manufacturer to properly size the electrical utility supply equipment (i.e., wire, electrical quick disconnect, overloads, transformers). Seek out a qualified electrical contractor in your area to assist in proper electrical utility modeling and sizing.


1) Proper placement and mounting is vital. Request a General Arrangement (GA) drawing from the OEM for each piece of compressed air equipment purchased. The GA drawing should illustrate the weight and recommended clearances to be maintained around the equipment. The floor will need to support the static weight of each piece of equipment. The equipment should be secured to the floor to prevent it from shifting around imparting stress on connected utilities such as piping, electrical and ducting. In addition, many states have adopted seismic codes mandating equipment be structurally secured to the floor. Many floors appear flat to the eye but are not flat enough to meet accepted equipment mounting practices. Many floors can be crowned (bowed) or have undulations. When securing equipment to a floor it is important to identify floor imperfections filling the air gaps with shims. When properly shimmed, the tightening of the mounting bolts will not bend or distort the equipment frame. Frame distortion will lead to excessive equipment vibration. Excessive vibration causes premature component failure which reduces machine reliability, increases the cost of ownership and could potentially create an unsafe situation.

Proper clearances should be adhered to. These recommended clearances provide boundary area around the machine for safe, effective operation and servicing of the machine. This boundary area also allows adequate cooling airflow around the machine.


All piping should be properly supported as to not impart stress on the equipment. When connecting piping to the equipment pipe connector, it should be supported with proper tooling to prevent the equipment connector from turning during the piping tightening process. If the equipment receiving connector is allowed to turn (rotate) it very well could damage internal components to the equipment. Air piping should be properly sized and configured to prevent short cycling of the air compressor controls. A rule of thumb is to always use piping at least the size of the supply connection of the air compressor. If the dryer connections are larger don’t worry, the reason could be the dryer is oversized due to rerating or simply the fittings are larger to slow the compressed air velocity down through the dryer. The piping exiting the dryer can be the same size as the air compressor connection or the outlet piping size of the dryer can be used to establish the piping downstream of the dryer.

Ambient Air

If the ambient air conditions can drop below 32°F measures should be taken to prevent the compressed air equipment from being exposed to this as it will freeze up. During air compressor operation the most effective way to condition the room temperature is to use the heat generated by the operating air compressor(s). Excessive heat can be discharged from the room by way of a properly sized wall fan. The wall fan can be thermostatically controlled to keep the room at a constant temperature. If there are times when all of the compressed air equipment is not operating, an auxiliary heating system should be considered.

Air-cooled rotary screw air compressors give off 2545 BTUs/hr per horsepower.

Example: A 50 horsepower air-cooled rotary screw air compressor discharges 127,250 btus/hr into its surrounding environment.

That is enough heat to keep a 1500 square foot home comfortable in the dead of winter with outdoor temperatures below 32°F.  Many of these air compressors are installed with little thought of eliminating heat build-up around the air compressor. The heat discharged into the ambient air surrounding the air compressor is continuously cycled through the heat exchangers elevating the temperature. Unchecked, the temperature will rise to an unacceptable level, eventually overheating the air compressor & shutting it down. Ducting can be attached to the air compressor to directly route the cooling air discharge outdoors or away from the rotary air compressor. Wall or ceiling fans can also be strategically placed in the room to exhaust the hot cooling air outside. Either way, an adequate amount of replacement cooling air must be brought into the room.

All installations have contaminants in the ambient air. Contaminants can negatively impact an air compressor in many ways. Two critical ways are indigestion into the air compressor itself with the other being fouling of the air-cooled heat exchangers. The best way to determine if the air compressor is digesting an abnormally high amount of contaminants is to consistently perform oil analysis. The oil analysis should look for components not normally part of the oil make-up. The results need to be properly interpreted.

In the case of a lubricated rotary air compressor, all of the ambient air drawn into the machine for compression flows right past or through the airend bearings. Too much ingestion of particulate will damage the bearings. The oil not only cools the air during compression it also washes the contaminants out of the air. Over time these contaminants will build up continuing to be cycled through the bearings.

Example:  A 10 micron particle should be able to flow through an anti friction bearing suspended in the oil film without damaging the bearing surfaces.

This does not account for multiple particles clumping together, which will damage the bearing surfaces. Two solutions for reducing digestion of contaminants are to install an air filter with a lower micron rating and higher efficiency rating. The ratings should be adjusted until the oil analysis indicates the level of contaminants is satisfactory. Remember, as the rating of the inlet air filter is increased the surface area should also be increased or the air filter may have to be changed out too frequently from excessive fouling. The second solution is to relocate the inlet air filter to a remote environment which is cleaner than the immediate area around the air compressor. The piping used to remote mount the air filter should be non-ferrous. PVC works great as it is light, easy to assemble and inexpensive. Connect it to the air compressor air end with an easily removable joint in case machine repairs or troubleshooting is required. The piping i.d. should be no smaller than the i.d. opening in the OEM supplied inlet filter mounting assembly. For every 10 feet of inlet pipe run, the pipe diameter should increase one size or 1". If the inlet air filter is relocated outdoors it should be protected from digestion of rain or snow.

Relocation of the inlet air filter is a recommended solution when the surrounding ambient area around the air compressor contains hazardous vapors or fumes. There are air filters which can remove hazardous fumes or vapors; however, they are costly to purchase and maintain.

If you have questions or would like more information or pricing, please visit our Distributor Lookup page on our website to locate a distributor in your area.

When Should I Service My Oil Flooded Rotary Air Compressor?

Each manufacturer’s make and model of rotary air compressor gives specific guidelines for preventative maintenance in the operations manual sent with the air compressor. You’ve invested a good deal of money in your new compressor, to protect your new investment it’s a wise idea to follow these preventative maintenance procedures. Keep in mind this is not a comprehensive list, but it’s a good start and will help give peace of mind knowing you are not neglecting your air compressor.

Every manufacturer of rotary screw air compressors provide an Operators Manual with specific guidelines for preventative maintenance. You’ve invested a good deal of money in your new compressor, to protect your new investment it’s a wise idea to follow the preventative maintenance procedures. Some compressor designs may require more steps and checks, but here is a good place to start to get the longest life out of your investment

Daily:   Check for abnormalities (unusual sound, vibration, leaks, warnings or alarms on the controller, etc.)

  • Check oil level
  • Monitor temperature and pressure
  • Check control panel for any alarms or maintenance lights

Monthly: Perform Daily checks

  • Clean inlet air filter and enclosure filters.
  • Check operation (load and unload, low and high pressure set-points, maintaining pressure, etc)

Quarterly: Check hour meter and check the maintenance schedule to determine if its time for maintenance to be scheduled. Your compressor may require lubrication change at 2,000, 4,000 or 8,000 hours depending on the manufacturer’s recommendations.

  • Take oil sample if needed
  • Check separator scavenger line flow (if applicable)
  • Check v-belts (if applicable)
  • Perform daily and monthly checks

Semi-Annual or 4000 hours:  Perform Quarterly Check list.

  • Change air/oil separator filters (spin on or drop in type)
  • Take oil sample and sent to compressor vendor

Annual or 8000 hours: Start by checking annual maintenance list for manufacturer’s recommendations:

  • Change lubricant
  • Change air / oil separator (drop in type)
  • Perform quarterly checks


Keep in mind; these are the basic maintenance items needed to keep an oil flooded rotary screw compressor in good operation. This preventative maintenance program is designed for a standard condition, but as we all know most installations for air compressors would be considered dirty and dusty environments.

Another factor that is critical to the life of a compressor is the actual run time. All rotary screw compressors underlying guideline for maintenance is hours of operation. Most installations never operate 24 hrs per day / 7 days a week. There are only 8760 hours in a year and anything less than 24 hours will result in lower hours, which affect the amount of maintenance needed for each installation.

So, with all of these factors to consider, what does an owner of an oil flooded rotary screw compressor do to properly maintain the air compressor to ensure long reliable operation?

To answer this question we need to look at several factors:

1)   Environment

First the environment is the one factor that governs all of the others. If your compressor is running in a dirty environment where you have to keep cleaning the coolers externally to keep the compressor cool and the air filter is continually dirty when you inspect it periodically; then you have a dirty environment. Use the monthly recommendations and not the hours of run time.

2) Hours of operation (less than 4000 hrs per year)

In this case the recommendation would be to follow the time frame set out for preventative maintenance as described in the operations manual. Use monthly intervals for filter changes and not the hours of operation as your guide. This means air and oil filters changed every quarter (or more frequently) as well as air/oil separators changed per instruction manual. Please note if you are running 24 hrs / 7 days then air and oil filters will need to be changed in accordance with OEM recommendations.

3) Costs

Costs of preventative maintenance should be only considered as a last resort as it has been proven in many studies that preventative maintenance saves money. A proper preventative maintenance program will translate into more reliable operation and less down times for the owner. This will create a more efficient production process for the owner which generates income on a consistent basis.

In all other instances the OEM manual should be used as a guideline for changing all filters for the proper maintenance your rotary screw compressor.

A properly maintained air compressor can be accomplished by following several practical guidelines and discussing your needs with an FS-Curtis compressed air professional. To learn more download the product information or contact your local FS Curtis distributor.