What is a Piston Compressor?

Piston compressors, also known as reciprocating compressors, have been one of the most popular types of air compressors since the 18^th century. While piston compressors still work on the same principle today as they did centuries ago, modern versions are relatively quiet, durable, and versatile compared to their predecessors.

Nevertheless, there are many specific types of piston compressors to choose from, meaning it is essential to understand the ins and outs of each one, so that you can invest wisely in the most suitable equipment for your environment and application.

Here at Anglian Compressors, we have been installing, servicing, and repairing all types of air compressors for businesses in the UK for almost 50 years. Not only are we a premier distributor for the esteemed manufacturer, Atlas Copco, but we are also experts in maximising workplace productivity, which is why we thoroughly inspect your site to recommend the most reliable and energy-efficient solutions available, whether you need air compressors, dryers, gas generators, filters, or a combination of the above.

We explain how piston compressors work, below, before introducing you to the available types. We also discuss the most common applications for reciprocating compressors and their pros and cons to help you purchase the most suitable appliance for your workplace. Do not hesitate to give us a call if you have any questions.

How Piston Compressors Work

Piston air compressors operate using the principle of positive displacement which means that they increase the pressure of the air by reducing its volume. The main components of these air compressors are valves and a piston that moves back and forth inside a cylinder.

You can also buy a reciprocating compressor that uses numerous pistons called multi-stage piston compressors (more on those later).

As the piston moves downwards, it draws air into the cylinder through the inlet valve. When the piston moves back up inside the cylinder, the inlet valve closes, forcing the air inside the cylinder to compress. The compressed air is then pushed through the discharge valve into the storage tank, where it is ready for use. This process is repeated in cycles to ensure you always have a continuous supply of compressed air.

Here is how reciprocating compressors work step by step:

1. Air enters the cylinder through the inlet valve.
2. As the piston moves downwards into the cylinder away from the inlet valve, the cylinder fills with air.
3. The crankshaft powers the piston. As the piston returns to its original position in a stroke of pressure, the air inside the cylinder is compressed through positive displacement (i.e. the air volume is reduced).
4. Once compressed, the air is sent through the discharge valve to the storage tank where it is ready for use.
5. The piston compressor repeats the process in cycles to ensure a constant compressed air supply.

Multi-stage compressors operate on the same principle as the single-stage compressors detailed above. The only difference is that multi-stage appliances use numerous pistons and cylinders to create higher pressures.

Types of Piston Compressors

In basic terms, all types of air compressors (pistons) operate on the same principle – the main difference comes down to how many steps are involved in compressing the air. You must also decide whether to purchase an oil-injected or an oil-free reciprocating compressor. Here are the essential considerations:

Single-stage versus double-stage versus multi-stage compressors

There are single-stage, double-stage, and multi-stage compressors. Splitting the compression into different stages makes the compressor’s job easier, and the air comes out at a lower temperature. For multi-stage compression to work best, the air should be cooled between stages; this is usually done with an intercooler. There are also oil-injected and oil-free piston compressors, each with advantages and applications.

Oil-injected versus oil-free piston compressors

Oil-injected piston compressors keep the cylinders, pistons and cranks lubricated by circulating oil throughout the machine. A small amount of residual oil might end up in the compressed air but, depending on what you need the compressed air for, it does not usually pose a significant problem.

Even tiny traces of oil in compressed air can cause problems in electronics, food and drinks, and pharmaceuticals. These industries often prefer oil-free piston compressors with permanently lubricated bearings and grease-free piston rings. While this ensures that the compressed air is free from oil contamination, it does mean that more maintenance is required.

Compared to oil-free compressors, oil-injected piston compressors usually have more moving parts. This makes them heavier, more expensive, and more powerful but they also tend to last longer. Despite the differences, oil-injected piston compressors are the most commonly used type.

Applications of Piston Compressors

Reciprocating air compressors are used in a wide range of industries, including:

• Automotive: powering pneumatic tools, spray painting, and tyre inflation.
• Manufacturing: pneumatic conveying, air-powered tools, and air separation processes.
• Healthcare: used in medical applications such as dental chairs, ventilators, and laboratory equipment.
• Commercial and personal settings: utilised in workshops, construction sites, and DIY projects for various air-powered tools and equipment.

Pros and Cons of Piston Compressors

In short, the pros and cons of piston compressors include:

Advantages of Piston Compressors

Piston compressors, also known as reciprocating compressors, are one of the oldest and most common types of air compressors due to several key advantages:

Versatility

Piston compressors offer versatility, making them suitable for various applications, from powering air tools in automotive workshops to meeting industrial air demands. They can efficiently deliver the necessary pressure level for both light and heavy-duty tasks.

Durability

Known for their robust construction, piston compressors can withstand harsh conditions and heavy use, providing reliable service over many years. Regular maintenance of the valve system and pistons ensures long-term performance.

High-Pressure Capability

Piston compressors use displacement compression, where air is drawn into a chamber and compressed as the piston moves upward. This allows them to achieve high-pressure outputs, which are ideal for tasks requiring precise and powerful air delivery.

Cost-Effectiveness

Piston compressors are generally more affordable than other compressor types. Their straightforward design and efficiency make them a cost-effective choice for businesses with intermittent air demand.

Ease of Maintenance

Maintenance is simple, with easy access to components for tasks like oil changes. Oil-lubricated piston compressors last longer with regular care, while oil-free models are ideal for applications requiring dry air.

Considerations:

• Maintenance: regular maintenance, including lubrication and valve checks, is essential for optimal performance.

Noise and vibration: reciprocating compressors can be noisy and may produce vibrations, often requiring professional installation and noise reduction measures.

Discover Our Range of Piston Air Compressors

Are you looking for modern, reliable, and energy-efficient piston compressors? Do you need a professional team of technicians to install your compressor to the highest industry standards? Anglian Compressors have been helping businesses, across a broad range of industries, with all their compressed air needs for over five decades. Whether you are looking for a new solution, servicing, repairs, or just general advice, we are only a phone call away. 

Contact us today to learn more about our range of reciprocating air compressors.