5 Must-Have Features in a Double-stage screw compressor

Our flagship product, the QR-25, is available in a 5 HP, 2-stage air compressor configuration. We also sell rotary screw and three-stage reciprocating machines. To learn more, check out our Resources page for more background on the technology and how it works.

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Quincy Compressor has been a leading compressor manufacturer for nearly 100 years. We carry a complete range of products, including two- and three-stage air compressors designed for heavy-duty industrial use. Our products incorporate advanced technology to improve efficiency, reduce noise and keep maintenance requirements to a minimum. The best warranty programs in the business back all of our products, and we offer extended coverage on certain components for 10 years or more.

Many reciprocating compressors come in both single- and two-stage options. If youve already selected a particular machine, you may be wondering whether you need a single- or multi-stage version. Here are six things to consider when choosing an air compressor to decide if a multi-stage system is right for your application:

Clearly, there are benefits to selecting a multi-stage machine. However, their higher cost means they are not necessarily the right choice for every application. Typically, single-stage compressors are best for lower pressure, light-duty, periodic use applications. Two- or three-stage air compressors, on the other hand, offer more efficiency and reliability for continuous use applications, such as manufacturing and auto repair.

Two-stage systems are smaller and can produce high-pressure air while taking up the same space as a single-stage system, though they cant match the output capability of a three-stage model. The latter will serve you better if space isnt a concern and your application requires greater efficiency and higher air pressure.

If you need an air compressor for demanding work like auto repair or manufacturing, investing in a two- or three-stage air compressor is necessary to ensure your unit produces an adequate supply of air for your tools or machinery. While both two- and three-stage compressors provide reliable air output, there are instances in which one will work better than the other.

Both single and multi-stage compressors have their benefits. The right one for your application will depend on a number of factors. Specific advantages of a three- or two-stage compressor design include:

A three-stage air compressor is a multi-stage compressor with three separate chambers. Air moves through a first compression stage and then passes through two heat exchangers and two additional chambers. The three-stage compressor provides the most consistent power output and can operate for extended periods.

In a two-stage compressor, the air passes through two chambers total. In the second chamber, it is pressurized to the required extent. In a three-stage compressor, an additional cycle of compression and cooling occurs before this.

Multi-stage compressors feature two or more piston cylinders, each of a different diameter. After the first compression stage, air passes through a heat exchanger, where it is cooled before arriving at the second cylinder. Cooling the air reduces the work needed to compress it during the second or third stages.

Reciprocating/piston compressors use a cylinder to force air into a chamber, where it is compressed. The simplest compressor designs feature a singlecylinder/chamber arrangement. While straightforward, this setup is limited in its efficiency and capacity for delivering high volumes of pressurized air.

If theres one thing thats constant about air compressors, its that their classifications are many and diverse. You could sort by storage tank size, electric motor horsepower, electrical phase, maximum airflow, maximum pressure, and many others. Among the other classifications is a single stage compressor versus a two-stage air compressor. What exactly is the difference between these two types of compressors, and does it really make that big of a difference to your operation? In this article, well discuss the biggest differences between the compressor types, in which situations a single- or dual-stage compressor may be more effective, and pricing differences you can expect to see from air compressors that have otherwise very similar specifications.

The Main Differences

Lets start out with what makes a single stage air compressor different from a two-stage unit: their stages. Generally speaking, you can tell this very quickly by looking at the piston system at the top of the air compressor. In a single-stage air compressor, air is drawn into the piston until its at full capacity, then pushed into a higher pressure and moved into the storage tank, reaching a top pressure of between 110-145 PSI. A two-stage air compressor starts out the same way, but before the compressed air is pushed into storage, its moved to a second compression using a smaller piston, where an additional step allows it to reach higher pressure yet to about 175 PSI. Because its under higher pressure, it can store more air at atmospheric pressure in cubic feet using the same sized tank when it reaches full capacity compared to its single-stage counterparts.

However, simply looking at the air compressor may not tell you enough about the machinerys potential. Some single-stage air compressors will use two pistons on top, with one filling as the other empties into the tank. The smaller cylinder tends to be the main giveaway for a two-stage air compressor, as it shows that the initial compressed air does not take up as much room as it did prior to compression. The two stages that are being referred to are the two separate compression processes that take place in a dual-stage air compressor system, providing you with higher air pressure in the end and more storage in limited space.

Another indicator to look for is a cooling system between the two pistons. Because of the additional amount of compression that must take place, the temperature of the air can go up significantly. To avoid possible mechanical problems from this heat, high-quality two-stage air compressors will have an intercooler that will cool the air between compressions. This helps cool the mechanical parts and prevent damage from overheating.

In most situations, single stage compressors will be used in portable applications and are typically hooked up to 120V outlet systems. By comparison, two-stage systems generally are permanent installations that usually require 240V power, though the rare one may take 120V at 20 amps, providing a significantly different plug compared to standard household outlets. Single stage air compressors will also often be lighter weight, making them popular for construction and other temporary job sites. Two-stage systems are much heavier, requiring mechanical assistance to move, which is why they are typically used in permanent locations.

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Uses for Single Stage and Two Stage

Though a single stage air compressor may seem like it has fewer moving parts and, therefore, is more reliable, this often isnt the case. Typically designed for single-user operations as well as homeowner and very light business use, single stage air compressors often fail more quickly because they are not designed for constant duty and continuous applications. In these situations, its very easy to get caught up in work and go over the compressors rated duty cycle, causing overheating and a shorter lifespan overall.

When you use an air tool or multiple tools in your business, youll have a particular range of PSI and flow that youll need to meet. Depending on the different types of applications and usage youre putting your compressor through, you may be able to get by with a single stage system, provided that you have a long enough duty cycle that the air compressor can rest on occasion. If your air compressor is constantly running or struggling to keep up with demand for compressed air in your situation, you may want to consider moving to a two-stage system.

However, thats not the only reason to make the change. As a whole, two-stage air compressor systems tend to be significantly hardier, as they are built for higher pressures and harder work. This is among the reasons why they will often feature an intercooler to help prevent mechanical breakdown. Theyre a great option for medium-sized shops that have not yet gone to rotary compressors which can work continuous duty cycles. They typically have larger tanks, allowing them to store more pneumatic energy for continuous applications. Theyre also energy efficient, allowing you to get more work done with a lower cost of electricity, propane, or natural gas.

Typically available as oil-filled compressors, youll still need to undertake basic maintenance, such as semi-annual, quarterly, or monthly oil changes, but because dual-stage air compressor systems are designed to have longer duty cycles and higher pressures, youll find that they can operate much more effectively than single stage air compressor systems, while their tough build makes them last much longer in most situations.

What is the Pricing Like?

So what kind of difference can you expect to see in terms of pricing between single stage and a dual stage compressor systems? As you might expect, there is a much higher level of engineering that goes into dual-stage compressors, mainly due to the higher pressure that they undergo, as well as the fact that it has more components compared to their single-stage counterparts. However, there are often many other aspects that should be taken into account. For this reason, weve selected two of our most similar air compressors, one of which is a single-stage and the other of which is a dual-stage system.

Single Stage: The Quincy VPQ Vertical & Portable Air Compressor $1,350

 As one of the few single-stage air compressors that we have, the has a 26-gallon storage tank and can reach up to 135 PSI. It features a two-horsepower electric motor that plugs into a standard household outlet, and the wheels display its portability, making it a decent option for construction sites and shops where your compressor must be moved around the shop space. It is, however, much closer to the weight youd perhaps expect from a permanent compressor at 165 pounds, with a powder-coated ASME tank, as well see on our next example.

Dual Stage: The Quincy QT-54 Vertical Air Compressor $2,925

By comparison, one of our smallest Quincy dual-stage compressors, the QT-54, has a 60-gallon storage tank capable of reaching up to 175 PSI. A sturdy five-horsepower electric motor requires a 230V outlet to manage its workload, and there are no wheels on this 475 pound permanent lightweight. Though its on the small side of permanent two-stage air compressors, it will provide plenty of pneumatic power for shops, but will not be taken out to temporary job sites often. 

As you can see, the pricing between these two models is fairly different, with the dual-stage compressor rating a much higher investment. However, it will also last longer, can store significantly more air in its storage tank, is built for higher pressure, and is designed for hard work over many years. For this reason, it makes a much better investment than the single stage, which may be replaced several times before the dual stage reaches its end of life.

Though youll have to decide whether a single- or dual-stage system is best for your situation and bearing in mind that this does not include rotary screw compressor systems, either type of compressor could provide you with excellent results. However, for most professional situations that do not involve individual air compressors at workstations, we recommend stepping up to a high-quality dual-stage air compressor for industrial work, as it will combine the higher pressure, longer lifespan, and superior energy efficiency youll need in continuous applications. 

Are you ready to make a change in your business to improve the operation of your industrial air compressor? Advanced Air & Vacuum has years of experience helping companies find the right solutions to their issues, from humidity levels causing corrosion to compressed air lines needing upgrading. If youre ready to take the next step, please feel free to reach out today with any questions, for more details, or for help finding solutions that meet your companys needs.

Reliable, energy-efficient air is needed for applications like medical device manufacturing.

Single- and two-stage air compressors have been around for a long time. However, other than the fact that a two-stage air compressor costs more, many end-users are not fully aware of the differences. Especially the ones that determine whether a two-stage model is a worthwhile investment.

Not surprisingly, a single-stage compressor uses one compression chamber to compress air to the desired pressure, while a two-stage air compressor uses two. The two look very similar.

So why would anyone pay more for the two-stage unit? We outline five critical reasons why below.

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