Reciprocating Compressors: Working Principle, Parts & Buyer’s Guide
Why reciprocating (piston) compressors are important
Reciprocating piston compressors, sometimes called just piston compressors or reciprocating air compressors, were some of the first machines invented to produce compressed air. As a positive displacement compressor, their design is constantly being refined as technology and materials improve, and they’re still widely used to this day. Many industries rely on reciprocating compressors for their compressed air needs.
Industrial reciprocating compressors are becoming a critical part of many industrial processes, and the need for these positive displacement machines is growing year on year. The market is expected to be worth USD 16.36 billion by 2024. You can find them being used in refineries, refrigeration systems using ammonia and other refrigerants, oil & gas, chemical manufacturing, automotive, agriculture, medical surgery and other industrial sectors. Chances are that if you’re reading this, you’re either a student or you work in one of these industries!
Air compressors are categorised by the working principle they use to produce compressed air — either positive displacement or dynamic displacement, such as rotary compressor or centrifugal compressor technology.
Reciprocating compressors use positive displacement, which is a method that relies on a law of gases called Boyle’s Law.
Reciprocating Compressor Working Principle
Reciprocating compressor’s working principle
Boyle’s law states that the absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if the temperature and amount of gas remain unchanged within a closed system.
This law shows us that a gas like air will increase its pressure as it passes through an enclosed space of decreasing size. The pressure and volume relationship is inversely proportional.
The working principle of a reciprocating compressor is based on reciprocating action. A piston moves inside a cylinder using a crankshaft and connecting rod mechanism powered by an electric motor. As compression occurs, gas is drawn in during the suction stroke through the suction and discharge valves.
The piston then compresses the gas by reducing the volume inside the cylinder, increasing pressure. Once the desired high pressure is reached, the discharge valves open to deliver gases into the outlet system for industrial use.
This positive displacement machine uses rotary motion from the motor and converts it into reciprocating motion, enabling it to compress air or gas efficiently for high-pressure applications.
How to pick the right industrial reciprocating compressor for your needs
Broadly speaking both positive displacement and dynamic displacement machines achieve the same objective - they compress and raise the pressure of gas.
So how do you know when to pick a reciprocating / piston compressor over a rotary compressor, or some other dynamic displacement machine as described in the diagram above?
You should start by making sure you’re looking for the right size of compressor.
This means knowing the amount of pressure (PSI) and flow (CFM) you need for your application.
There are various types and models of reciprocating compressors suitable for different compressed air needs — use our product selector to filter our range until you find your ideal product.
Notice how reciprocating compressors have very high maximum discharge pressure, making them suitable for high-pressure applications such as PET blowing and certain gas compression systems.
Here are some things to consider when buying a reciprocating compressor:
Do you need to produce clean air, dry air, or oil-free air?
How many hours per year will you be operating the compressor?
Will the compressor be running continuously or in shifts?
Does your air compressor demand fluctuate throughout the day?
Will you be expanding soon? Will your requirements change in the near future?
It also depends on who’s making the purchase decision.
Engineers are often required to make judgment calls based on what is best for the overall industrial project, not just the specific application of the compressor. They may be constrained by technical, commercial, scheduling, operating temperature conditions, and future expectations.
Here are some non-technical things to consider:
Operating conditions (present and future)
Quality and durability of the equipment brand
Available skills for maintenance
Staff familiarity with reciprocating compressors
Automation and digital controls
Availability of spare parts and compressor valves
Delivery time
Price and Life-Cycle Cost
As you can tell, there’s a lot that goes into selecting the right reciprocating compressor.
And it starts by understanding your exact compressed air needs, pressure requirements, efficiency targets and potential inefficiencies.
That’s why we recommend consulting with an Atlas Copco expert who can guide you over email or phone, or conduct a FREE energy efficiency audit at your site.
The advantages of reciprocating compressors
Changes in the molecular weight of the gas composition can significantly affect compressor operation.
Positive displacement compressors are more tolerant of changes in gas composition than dynamic machines like rotary or centrifugal compressors.
If we choose a positive displacement compressor, we must understand the advantages reciprocating compressors offer:
The working principle is simple, which means the machinery is less complicated and more cost-effective. They are generally cheaper to manufacture and maintain.
The technology is well known across industries, making maintenance easier and ensuring reliable performance.
Spare parts such as piston components, compressor valves, suction and discharge valves, crankshaft assemblies, and connecting rods are widely available and affordable.
There is a wide range of sizes and stages suited for small businesses as well as larger industrial facilities.
Smaller belt-driven models are portable and suitable for site-specific applications.
Reciprocating compressors also provide high efficiency and high maximum discharge pressure, making them highly efficient for high-pressure applications.
They are commonly used where reliability, durability and performance are critical.
Why investing in Atlas Copco’s reciprocating air compressor solutions makes sense
Headquartered in Sweden and operating in over 180 countries, Atlas Copco has been providing industrial compressed air and gas solutions since 1873.
Our vision has always been to be First in Mind—First in Choice as a supplier of compressed air systems in the UAE and worldwide.
Over the years, we’ve discovered that being interactive, committed and innovative is the key to offering customers the best value and optimizing performance.
Our clients benefit from continuous breakthroughs in optimizing compressors for energy efficiency and energy savings.
Did you know that air compressors account for 12–40% of a facility's yearly industrial electricity consumption?
However, not all supplied energy is effectively used. Energy losses occur due to:
Heat production
Air leaks
Friction between moving parts
Poor compressor design
Improper maintenance
Our reciprocating compressors are market leaders in energy efficiency, reliability and innovation.
The Atlas Copco range includes highly efficient reciprocating air compressor models suited for various industries and applications.
Available variants include:
Belt driven
Direct drive
Dental air
PET blowing
Compressed Natural Gas solutions
We recommend consulting an expert to guide you through the working principle, components, operating conditions and suitable models for your facility.
Don’t forget to take advantage of our FREE energy efficiency audit when you contact us.
We can arrange for an expert to visit your site.
The audit may include a visual inspection or a complete system evaluation, solving for leaks, pressure drops, compression inefficiencies and optimizing overall system performance.
Atlas Copco Compressors Deliver on Their Promise
Our customers maintain long-term working relationships with us because we prioritize reliability, quality, durability and smooth industrial operation.
We ensure that your compressed air systems operate efficiently, reliably and with minimal maintenance concerns.
We remain committed to designing reciprocating compressors that deliver tangible benefits in productivity, energy efficiency, reliability and lower life-cycle cost.
FAQs
1. What is a reciprocating compressor, and how does it work?
A reciprocating compressor is a positive displacement compressor that uses a piston inside a cylinder to compress air or gas. Compression occurs through reciprocating action driven by a crankshaft and an electric motor using suction and discharge valves.
2. What is the difference between a reciprocating compressor and a rotary compressor?
A reciprocating compressor uses a piston and cylinder for high-pressure applications, while a rotary compressor provides continuous flow using rotary motion. Reciprocating models are better suited for high-pressure and intermittent industrial use.
3. Where are reciprocating air compressors commonly used?
Reciprocating air compressors are commonly used in refineries, refrigeration systems using ammonia, PET blowing, automotive workshops, and various industrial compressed air applications requiring reliable performance
4. What are the main advantages of a piston compressor?
Piston compressors offer high efficiency, cost-effective operation, easy maintenance, durable components, and availability of spare parts. They are highly efficient for high-pressure compressed air needs.
5. How can I improve the energy efficiency of my reciprocating compressor?
Regular maintenance, checking compressor valves, reducing air leaks, monitoring pressure and temperature, and conducting energy audits can significantly improve efficiency, performance and energy savings.
