Rotary screw compressors are used across many industries. For example, machine shops, food factories, packaging operations and many more.
The reason for these compressors’ popularity is their low wear-and-tear and their ultra-quiet operation.
In this detailed buyers guide, we are going to go into who uses rotary screw air compressors, the benefits of using such compressors, their cost, and their disadvantages.
Who Uses Rotary Screw Air Compressors?
Rotary screw air compressors have the following industry applications:
- Papermaking and Printing
- Metallurgy and Mining
- Household Appliance
- Medicine and Health
- Petrochemical Engineering
- Electronic and Electrical
- Light Industry and Food
- Textile and Clothing
- Construction and Building Material
- Electric Power
Rotary Screw Air Compressor vs. Piston Air Compressor
Also known as a reciprocating compressor, a piston compressor uses pistons driven by a crankshaft to deliver gases at high pressure. It is a positive-displacement compressor.
The intake gas enters the suction manifold. After that, it goes into the compression cylinder, where a piston compresses it. The piston is driven in a reciprocating motion via a crankshaft.
Applications include refrigeration plants, oil refineries, gas pipelines, natural gas processing plants, and chemical plants. One specialty application is the blowing of PET (polyethylene terephthalate) plastic bottles.
A lot of seals and bearings were removed in the design of ionic liquid piston compressors. This is because the ionic liquid does not mix with the gas. Service life is much longer than that of a standard diaphragm compressor with minimized maintenance during use.
The energy costs are reduced by as much as a fifth. The heat exchangers we use in a standard piston compressor are eliminated along with the heat where it is generated – in the cylinder. Almost all of the energy going into the process is used with very little lost as reject heat.
Best Rotary Screw Air Compressors
1. Atlas Copco GX4 5-HP 53-Gallon Rotary Screw Air Compressor
This model by one of the largest compressor manufacturers Atlas Copco is a powerful and reliable solution for many small and medium-sized industries.
It can operate in the desert, where temperatures often reach as high as 46 C.
Moreover, the pace of its rotary screw adjusts according to the amount of air required to power up the specific tool.
Thus, GX4 is one of the most economical 5-HP air compressors currently available on the market. This unit’s tank size is 53 gallons and it produces 16.5 CFM at 150 PSI.
- Heavy-duty belt drive
- Low-noise rotary technology
- Space-saving horizontal tank
- No electronic drain valve
At the same time, its 7.5 HP ODP electric motor generates 28 CFM at 90 PSI, while the PSI max has been set at 125.
Yet, its relatively small tank of just 80 gallons makes this model of Ingersoll Rand unsuitable for large-scale industrial jobs, which require a lot of compressed air.
Rather, this is the choice of the car painter or the local handyman.
In addition to the single-phase, version, there is also a three-phase modification of the same model.
Before the operation, it should be fixed to the ground or other flat surfaces with massive screws and rubber pads to avoid vibration.
- Quiet operation
- A steady output of compressed air
- Minimum maintenance required
- Relatively high retail price
The variable screw speed option makes it perfect for large, as well as small jobs.
At the heart of all of Quincy’s QGV®️ compressors is a flex-drive air-end with a 100000-hour design that guarantees easy maintenance and reliable operation.
As this is a tank-less unit, it can hold pressure +/- 2 psi. because of its quiet operation at about 68 DB, this model is suitable for use at home and in urban areas. All QGV compressors come with a 10-year exclusive warranty.
- Adjustable screw rotation for added versatility
- 10-year royal warranty
- Very quiet operation at 68 DB
- No tank
First Air’s rotary screw air compressor boasts an ergonomic design, well-balanced performance, and unprecedented versatility.
Its 53-gallon horizontal tank is conveniently placed below the engine and the control panel, so as to save maximum space in the workshop.
Although it can also cope with some industrial applications reasonably well.
This unit has no wheels and has to be fixed to its fundament with bolts or massive screws.
Still, its high-quality components ensure the compressor’s durability even when put to work 24/7.
Thanks to its very efficient cooling system, it works without a problem at temperatures reaching 45 C.
This rotary screw air compressor with dryer is equipped with energy-efficient driving motors class IE3 that generate a total of 7.5 HP.
It also has protection class IP55, and insulation class F.
When in operation, the unit’s noise level is up to 65 DB.
Few components are more important to a rotary screw compressor’s life than the filter. FAS6U’s high-performance filter prevents contaminants from entering the air system.
At the same time, the air dryer condenses the air to remove airborne moisture, dirt, and oil before it enters the compressor.
- Efficient cooling system
- High-quality air filter
- Energy-efficient electrical motors
- 1-year factory warranty on the parts only
The RS140GEC30 model portable air compressor by CAS is a true air beast! Its heart is a perfectly-built 13-HP Honda engine that generates 20.5 CFM at 150 psi.
This CAS portable screw compressor has been designed for the most demanding portable compressor jobs.
The screw air end is designed to take years of service in long duty cycle applications.
If your job demands high cfm output in a compact design, the CAS portable screw compressor is built just for you!
To save energy, this unit’s electric-start motor idles when unloaded, while the 30-gallon tank holds enough air to power up most of the tools on the building site.
The rotary screw, one of the compressor’s most important components is made in Germany with absolute precision and attention to the tiniest detail!
The compressor’s NK 30 pump generates the mind-blowing 3,000 rotations per minute.
- Super-reliable Honda engine
- German-made airscrew
- Electric-start motor idles when unloaded
- The price is a bit too high for a portable unit
Eaton Compressor’s 50-HP rotary screw air compressor is a true industrial gem. Its heart is the 3-phase, gear-driven, fixed-speed electric motor.
The Direct-drive function reduces the workload on the pump and the motor drive bearings. This eliminates the need for belt maintenance.
The company’s Y/DeltaSoftStart system limits the voltage on startup, making this unit one of the most energy-efficient rotary screw air compressors that money can buy.
In fact, this system reduces energy demand by one-third.
The Tamrotor/GardnerDenver rotary air end is designed with precision in mind. Moreover, it is covered by one of the longest warranties in the compressed air industry – a full decade!
The other parts of the compressor are covered by a 5-year warranty, which is well above the average warranty in the sector.
The PLC Controller
The compressor’s smooth operation is guaranteed by the PLC controller. It monitors temperature, oil level, and filtration, and alerts the operator if maintenance is required.
When in use, this compressor is surprisingly quiet (79 DB). Yet, it generates 235 CFM and 100 PSI, while the PSI max is set at 145.
- Very long warranty
- Extremely energy-efficient
- Very quiet operation
- Not enough info about tank sizes
EMAX’s ERV0150003-208 model is a tankless rotary screw air compressor with a 15-HP, 3-phase variable-speed electric motor.
As per the manufacturer’s information, this unit is great for industrial and manufacturing applications.
This is so because it has low energy demand and amp draw on startup.
The Spin-Tek system, unique for this manufacturer, provides easy access to the compressor’s oil filters and air/oil separators.
This unit is designed to be used with a stationary air receiver. At the same time, we were surprised to find out that it is bought separately.
The situation with this compressor’s warranty is very interesting, indeed. The air end and the pump are covered for a full decade.
Then, there is a 5-year warranty on the cabinet and the motor. Finally, all of its electric parts are protected for two years. Please note that SERVICEKIT003 Maintenance Kit required to validate warranty coverage.
- Great productivity for a 15-HP unit
- The design allows for easy maintenance
- Economical and quiet
- Stationary air receiver not included in the package
Atlas Copco’s G7-125 model is equipped with a 120-gallon, horizontal tank located right under the cabinet.
This rotary screw air compressor is built from the best parts and materials to provide a 100% duty cycle for long periods of time.
It delivers 40 cfm at 125 psi from its 10-hp motor. The rotary screw elements are designed to be efficient and quiet.
In addition, the sound dampening enclosure further reduces noise levels.
As a three-phase compressor, the G7 is designed to function with most power tools.
It comes complete with a 2-year end-to-end warranty from Atlas Copco on the parts and service.
The compressor’s topside cooling system guarantees low energy costs and a relatively small footprint.
Please note that in some sources the warranty is listed as “one-year bumper-to-bumper”.
- Quiet operation
- 100% duty cycle
- Low energy costs
- Does not have a variable speed function
Chicago Pneumatic’s QRS model is our top choice in the 5 HP class. It comes with a 60-gallon tank and a 230-Volt, Single-phase electric motor.
You can’t expect it to generate enough power to perform construction site jobs reasonably well. Instead, you should use it in your tire shop, service shop, paint shop or your garage.
We found out that QRS actually stands for “Quiet Rotary Screw”. When in use, this compressor makes just 62 DB of noise.
Still, its TEFC motor generates 16.6 CFM at 150 PSI, while the maximum PSI is set at 175.
The sixty-gallon tank has to be drained manually. We were surprised by this minor inconvenience, as most other models are equipped with an automatic tank drain system.
The standard factory warranty on this unit is one year. If you want a longer warranty, you’ve got to pay extra.
- Manufactured with precision from top-quality materials
- Very quiet operation
- Perfect for use at home or in the garage
- The owner has to pay extra for an extended warranty
KAISHAN’s 126 CFM Mini Rotary Screw Air Compressor is for those who want to shop on a budget. If you trust the Chinese way of making machines, this little boy is for you.
This is an oil-free unit that delivers 3.6m³/min / 126cfm, 2.7m³/min / 95cfm, and 3.2m³/min/112cfm.
It’s working pressure is: 0.8mpa/ 8 bar/ 115psi and the shipping weight is just 700 kg, which is very light for a rotary screw air compressor, mind you!
KAISHAN has commissioned the US company SKK to manufacture their compressor’s air end. Similarly, Austria’s Hoerbiger has manufactured this unit’s intake valve/
So, you should not worry about build quality, if you are planning to buy this model.
- Available in 3 modifications depending on your specific air needs
- Very detailed tech specs provided by the manufacturer
- The contact form at the bottom allows you to quickly place an order
- KAISHAN still isn’t among the big names in the field of rotary screw air compressors
BelAire’s BR75501 is our choice in the industrial rotary screw air compressor class. And this fat boy is really built to supply compressed air to big tools working on large scale projects.
Its heart is a 230-V 7.5-HP electric motor, whose output is just massive! It generates 21.2 cfm at 150 PSI.
At the same time, the sixty-gallon tank stores just enough air for the needs of most industries.
This rotary screw air compressor by BelAire is built to provide reliable and efficient compressed air for the industry.
This rotary screw compressor allows for 100% duty and extremely quiet operation.
- Reasonable productivity
- High-quality build
- Suitable for heavy-duty industrial use where 100% duty cycle is required
- We are not sure that the 60-gallon tank is the right one for this model
Hertz’s HDD-22 is the smallest representative of their HDD product line and that’s why we selected it for your home shop.
Frankly speaking, you do not really need a rotary screw air compressor for your DIY projects. Better buy a much-cheaper piston compressor!
The best features of this model include durable and efficient power transfer thanks to the use of elastic coupling.
The coupling system itself can be set up in just half an hour. The PTC motor bearings and windings protect the electric motor of this compressor from overheating.
The Cooling System
The cooling system consists of silent and slow-speed radial fans that are controlled with secondary fan inverter and independent radiator segments.
If you are planning to save on heating during the winter, this compressor has got an oil tank heater for cold environments.
- The list of features and extras is really long
- We were really impressed with the oil tank heater
- Efficient power transfer for maximum productivity
- Warranty period not specified
Types of Rotary Screw Air Compressors
Gas Powered Rotary Screw Air Compressors
Gas-powered rotary screw air compressors offer the benefit of a rotary screw air compressor without having big output hydraulic drive systems on your work truck. You have the portability that lets you get your compressor closer to your work along with that, with add on wheel kits.
Powers Up Multiple Tools
Power heavy air tools and seat beads re-inflate tires on even the biggest and heaviest equipment tires. What is more, you can have up to 185CFM @ 150PSI air pressure at once with a rotary screw air compressor without an air tank or air reservoir.
Who is it Great For ?
These rotary screw air compressors are good for applications like rental, monument engraving, post pounding, irrigation service, directional boring and general construction. They increase gas pressure by reducing its volume.
Compressors are not unlike pumps in that they can transport the fluid through a pipe and increase the pressure on a fluid. Due to the fact that gases are compressible, the compressor also limits the volume of a gas. Liquids are pretty much incompressible. The pump’s main action is to pressurize and transport liquids.
Mini Rotary Compressor
Mini or micro rotary compressors have applications in robotics, medical devices, “nano-satellites”, and more. The problem with active cooling for photodetectors in “nano-satellites” becomes critical because the majority of space missions, for example, target Earth observation.
With passive cooling, the required temperatures for desired SNR levels are not achieved. Piston compressors used in cryo coolers generate vibrations. The company VERT Rotors built an ultralow-vibration rotary compressor with 40mm-long screws.
This “nano” compressor is an untraditional, conical type comprised of an inner conical screw rotor revolving inside an outer screw rotor.
The need to develop a tiny rotary compressor with high heat removal, compression ratio, and temperature control has become a crucial issue with “nano-satellites” (100x100x100mm – scale, so-called “CubeSats”) and small satellite platforms (1m x 1m x 1m – scale). An active heat rejection technology is required with increasing power budgets.
The Cheaper Option
Mini rotary screw air compressors are also cheaper than standard ones. If you get lucky with one made in China, you’ll save lots of money. On average, oil-free mini units deliver 2.7m³/min / 95cfm, 3.6m³/min / 126cfm, and 3.2m³/min/112cfm.
The shipping weight is less than 800 kg, which is quite light. The build quality of mini compressors is good. Some of them are available in different modifications, come with very detailed tech specs provided by the manufacturer, and are quick to order.
Oil Flooded Rotary Vs Oil injected
The two main types of rotary screw compressors are oil-flooded or oil-injected and gas rotary screw compressors. With the first kind, oil is injected into the compression cavities to facilitate sealing and supply the gas charge with a cooling sink. The discharge stream is separated from the oil. The oil is cooled, recycled, and filtered.
The oil captures non-polar particulates from the incoming air, thereby reducing the particle load of compressed-air particulate filtration. Normally, some compressor oil spills over downstream of the compressor into the compressed gas stream. In many applications, this is rectified by filter vessels.
Refrigerated Compressed Air Dryers
Refrigerated compressed air dryers are rated to remove more water and oil than coalescing filters that are downstream of air dryers. This is because after the moisture is removed and the air is cooled, the cold air is used to pre-cool the hot incoming air, which heats up the air exiting.
In other applications, this is remedied by the use of receiver tanks that limit the local velocity of compressed air, which lets the oil condense and be removed by condensate-management equipment from the compressed-air system.
The Oil Injected Compressors
Oil-injected rotary-screw compressors are used in pneumatic tool operation, crack sealing, and mobile tire service among other applications. All applications that tolerate a low level of oil contamination can use them. New oil-flooded screw air compressors release oil carryover of <5mg/m3.
PAG (polyalkylene glycol) oil lubricants are used by the two biggest American air compressor OEMs in rotary screw air compressors. As PAG oil dissolves paint, oil-injected compressors are not used to spray paint. Reaction-hardening, dual-element epoxy resin paints resist to PAG oil.
PAG compressors are not great for applications that involve mineral oil greases coated seals, such as air cylinders that do not work with mineral oiler lubricators and 4-way valves. This is because the PAG degrades Buna-N rubber and washes away the mineral grease.
Rotary Compressors Vs Other Compressors
In the paragraphs below, we are going to draw a head-to-head comparison between the rotary screw air compressor and its closest competitors – the piston compressor, the centrifugal compressor, and the rotary tooth compressor.
1. Rotary Screw Air Compressor vs Piston Compressor
The two most popular types of compressors are rotary screw air compressors and reciprocating (or piston) air compressors.
To begin with, piston compressors are far more affordable with retail prices starting at $100 or $200. By contrast, rotary screw compressors are generally pricier, with retail prices starting at $5,000.
Therefore, piston compressors are more suitable for DIY projects and home use, while rotary screw compressors are mostly used in the industry.
The former type of compressors is capable of maintaining a 100% duty cycle over a shorter period of time. The latter type can maintain a 100% duty cycle for longer.
Finally, rotary screw compressors are generally quieter than the ones with pistons.
|Feature||Rotary Screw Compressors||Piston Compressors|
|Pace of operation||++++++||++|
2. Screw Compressor vs Centrifugal Compressor
A centrifugal compressor is a radial flow rotodynamic fluid compressor that uses air as the working fluid. Centrifugal compressors use very high-speed spinning impellers (up to 60,000 rpm) to accelerate the air.
Then the diffusers in the device slow the airflow down.
This process, called dynamic compression, uses velocity to cause an increase in pressure.
Generally, these compressors have intercoolers between each stage to cool the air as well as remove 100% of the condensate to avoid impeller damage.
|Feature||Rotary Screw Compressors||Centrifugal Compressors|
|Maximum PSI||175||Up to 1,200|
3. Rotary Tooth Compressor vs Rotary Screw Compressor
The rotary tooth compressors are displacement compressors that have two rotors, male and female. These rotors move in opposite directions within the compression chamber.
They are controlled by a set of gear wheels to guarantee optimal compression.
As the rotors turn toward each other, they draw in air. Intake stops once the rotors have turned to completely block the inlet port.
Rotary tooth compressors are mostly used to supply extremely pure compressed air to labs and hospitals.
|Feature||Rotary Screw Compressors||Rotary Tooth Compressors|
|Quality of compressed air||Not suitable for hospital use||Suitable for hospital use|
How Rotary Air Compressors Works ?
A rotary-screw compressor is a type of air compressor equipped with a rotary-type positive-displacement mechanism.
They have been invented as an alternative to traditional piston compressors that use large volumes of high-pressure air
The gas compression process by means of a rotary screw generates insignificant pulsation or surging of flow that is very common in piston compressors.
For this reason, screw compressors are also much quieter and generate less vibration than their piston rivals.
Rotary screw air compressors are most efficient in large industrial applications or to power up huge air tools such as gigantic jackhammers and massive impact wrenches.
An industrial rotary screw compressor has a 100% duty cycle. It can operate 24/7 without a break, and it is meant to be used that way.
the heart of every such unit is the rotary-type positive-displacement mechanism, which has become a viable alternative to the traditional piston.
Continuous & Uninterrupted Supply
Rotary screw compressors are designed to provide a continuous and uninterrupted supply of compressed air to industrial and construction sites, paint shops, and other businesses. They are relatively expensive and also quite heavy.
For these reasons, we do not recommend you buying one of the bad boys reviewed in the sections above for your home or garage.
Most of the models discussed above are powered by single or multi-phase electric motors, but there are special models that can run on different fuels.
Including gasoline and diesel. Their PSI max ranges between 150 and 175, while the CFM varies between 16 and 235.
While all piston air compressors require a tank to store the compressed air, in the big table above we can see some tankless models.
As per the table, the leading manufacturers of rotary screw air compressors are Ingersoll Rand, Quincy and Atlas Copco.