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Don’t Scroll On These Scroll Compressors

Scroll Compressor

Compressed air is an incredibly valuable utility. It is the heartbeat of many industries and provides an invaluable power source. Air tools can be used in potentially dangerous environments that need to be sterile and other specific situations. Operations that involve human consumption or internal use typically use scroll compressors due to their lack of oil and quiet nature.

With your traditional air compressors, there is an expectation of high volume, vibrations, and the constant noise of the machine starting and stopping. Noises of pistons slamming up and down, air being pumped downstream, and the droning noise of air tools can fill up a room pretty easily. 

Some people cannot have this noise in their work environment. Whatever the specific case may be, there are applications where your traditional-style compressors are not going to cut it. Dentist offices are the prime example of someplace that needs high-quality compressed air and needs it close by, something a piston could definitely not do.

Scroll compressors excel in the areas where reciprocating compressors fall short. Piston compressors are known for their high volume output and their loudness. These things usually require their own separate room or are far away from the point of use and are then piped in. Scroll air compressors compress the air very differently than a piston or screw would.


How Does a Scroll Air Compressor Work?

So these things are the perfect fit for operations with smaller demands and need high-quality air without a lot of noise, but how exactly can they do that? Thankfully, the scroll process is much simpler than the others due to being limited in size by technology. 

Scroll Component

The compression mechanism consists of two scrolls, one that is fixed and one that orbits around the fixed one. As the orbiting scroll opens, air flows in and is trapped in the space between the two scrolls. The gas is trapped in those crescent-shaped pockets, and as the scroll rotates and the space decreases, the pressure continuously builds up. 

Movement of the parts creates suction and pulls the air in until the front of the scroll comes as close to contact as possible, and the pocket is sealed. Rotations continue, and the pocket size decreases until it reaches the discharge port in the center.  By continuously moving, multiple pockets of air are being compressed and released in rapid succession. 

As you may have noticed, the components on these machines don’t actually come in contact with each other. Unlike piston or rotary screw compressors which require some form of lubricant in the compression chamber, these machines are so finely tuned that they are able to create compressed air without having the components come in contact.

If you are more of a visual learner, checkout the video below by Atlas Copco on Scroll Air Compressors.



What Makes It A Scroll Air Compressor?

In order to identify a scroll air compressor, there are 3 identifying and important characteristics.

  1. Six gas pockets are being compressed at the same time.
  2. The compression progress requires only an orbiting motion.
  3. The compression process is continuous, about 2 revolutions is a full pocket cycle. 


If a compressor meets these conditions, then you can safely say that it is a scroll air compressor. It would be hard to confuse a scroll with a piston compressor even if you didn’t know anything about compressed air.

These key features are responsible for a lot of the benefits that scroll compressors can provide. Due to the decreased noise and continuous compression, these machines are much more efficient than their counterparts. 

Scrolls have many benefits from a financial view and from a technical point of view at the same time. The technology reduces noise and increases reliability of the components. Not only do they save money on operating costs, but also save money on maintenance costs and requirements. 


The Benefits of Scroll Air Compressors

For many reasons, scroll compressors are considered inherently more efficient when compared with their industry counterparts. A multitude of reasons enhance the efficiency of scroll compressors in ways that are not feasible for pistons or rotary screws.

Due to not having pistons, which require a period where compression does not occur due to the piston having to reset. Now this isn’t a problem, but it does prevent the compressor from getting to 100% volumetric efficiency like the scroll air compressor.

This efficiency loss is called the re-expansion loss. The nature of piston strokes results in this time of being unable to produce compressed air. Piston compressors also lose air due to valve port discharges, however, scroll air compressors do not have suction or discharge valves for this efficiency loss to occur.

Alongside not having as many opportunities to lose air, these machines have less moving parts and have a considerably quieter base operational volume. Scroll compressors can operate between 5-15 dBA below your typical air compressors. Alongside the obvious, fewer moving parts, lower volume, and less friction means your compressor is going to be more durable.

Scroll compressors’ lighter weight and footprint are considerably smaller than their bulkier counterparts. Considering all the benefits these compressors provide, this is just the cherry on top. The benefits of these compressors are in a league of their own.


When To Use a Scroll Air Compressor

Most of the applications involving scroll compressors are going to require high quality air, at least class 2 and below. Industries involving food and fruit refrigeration, dentistry, and other industries that require air to the degree. Aside from those few groups, the rotary screw is the preferred choice for most industrial applications.

The scroll is suited to smaller applications and operations that require lower volumes of air due to the size restrictions on these compressors. Due to the nature of the scroll component, you can only go so large without losing pressure and compression efficiency. Instead, bigger units will have multiple scroll pumps included.

For larger applications, the scroll is not the logical choice when compared to a larger single compressor like a screw. This option just makes more sense when you compare it to having to use multiple smaller compressors to output the same volume of air. However, if you are running a lab, the scroll might be your best fit.

When it comes to your scroll compressor, you aren’t restricted by duty cycle; unlike the reciprocating compressor which is not recommended to run at 100% duty cycle or rotary screw which is not recommended to run below a 50% duty cycle. Scroll compressors are able to excel in both of these duty requirements. 


All the Air, None of the Friction

While we have been talking about all of the advantages of the scroll air compressor, we cannot ignore the disadvantages of them as well. Although they are very good machines, they are not perfect and have shortcomings. 

Because these compressors are fully hermetic, they cannot be disassembled to be maintained. These machines are incredibly difficult to repair due to this and often are unrepairable if they break. 

Unlike your reciprocating compressors that can rotate in both directions, scroll compressors have one direction that they can rotate/orbit in. This makes it very important to have your scroll properly installed.

However, if a scroll is what you need, don’t let these deter you. Scroll compressors excel in their applications and will cut your energy costs way down if you were using a different machine. To keep things short and sweet, the benefits to the scroll air compressor are:

  • 100% Duty Cycle
  • Truly Oil-Free/ High Quality Air
  • Quietest Compressor
  • Small But Efficient


And that really sums up all you need to know about the Scroll Air Compressor and why you might need one in place for your own application. If you are considering your own, check out all the scroll compressors we have to offer. If you see something you may like but are unsure about stock feel free to give us a call.


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From Atlas Copco

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