Air Supply UK: Specialist Compressed Air Engineers

Published: 17/07/2020

How to Choose the Right Industrial Air Compressor

We rely on air compressors for much more than you might think, and they have a wide range of useful applications, both in our day to day lives and across many commercial and industrial industries. Unless you work in an industrial environment, you may have no knowledge or awareness of this machinery and how it works, but air compressors also feature in our homes more prominently than you might expect.

If you’ve ever used a pressure washer, bicycle tyre pump or a pneumatic drill, then you’ve used a tool powered by an air compressor. While these devices are highly useful for domestic tasks, industrial air compressors are where we get to see just how vital this machinery can be. Used by a wide variety of industries, including the marine, agricultural and pharmaceutical sectors, industrial air compressors allow production lines and machinery to run smoothly and efficiently.

It’s vital to ensure that you choose the right industrial air compressor if you want your business to be as productive as possible, so if you want to know more about what these compressors are, how they work and the right type to choose, read on for our handy guide.

What is an industrial air compressor?

An air compressor is a device that converts power (using a gas engine or electric motor, for example) into potential energy stored in compressed air. An industrial air compressor is simply a compressor that’s used for industrial applications, such as powering tools, operating factory machinery, spraying crops, pressure washing, or sanding. They’re used in a wide range of workplaces too, including oil refineries, gas pipelines, chemical plants, natural gas processing plants and refrigeration plants.

There are three different types of air compressor which are most commonly found in industrial applications:

Reciprocating compressors

Also called a piston compressor, these models are the most common type of air compressor for mobile applications. They work via positive displacement; using pistons driven by a crankshaft to deliver gases at high pressure. First, intake gas flows into the suction manifold and then into a compression cylinder, where it’s compressed by a piston driven in a reciprocating motion via a crankshaft, which is powered by an electric motor or gas engine.

As the piston moves down, a vacuum is created above it, which allows outside air to push open the inlet valve and fill the space above the piston. When the piston moves up, the air above it compresses, holding the inlet valve shut and opening the discharge valve so that air can move from the discharge port to the tank. With each stroke, more air enters the tank and the pressure rises.

This type of compressor is suitable for low duty cycle operations and they tend to have the lowest purchase price point. They’re also easier to rebuild, but they tend to be much larger and heavier than other compressor models.

Rotary screw compressors

This type of compressor is more common in stationary applications and they are becoming more widely used across a diverse range of industries. These compressors use a rotary screw to compress gas in a continuous, sweeping motion, allowing them to be much quieter and produce less vibration in comparison to piston compressors of the same size.

They contain two helical rotors which interlock within the air compressor unit and ambient air then enters the compressor through an inlet valve and becomes trapped between the rotors. There, the screws turn, which increases the pressure of the air by reducing its volume.

Rotary compressors are commonly used in place of piston compressors for applications where large volumes of high pressure are needed (such as larger industrial jobs or to operate high-power air tools).

Rotary vane compressors

This type of compressor isn’t as widely used and there are fewer manufacturers for them, in comparison to reciprocating compressors. They consist of vanes mounted to a rotor which rotate inside the compressor cavity, and these vanes can be of variable lengths and tensions. These compressors have fewer moving parts and are more compact in size, but they can be complex to operate and are considered less suitable for high-viscosity or high-pressure fluid applications.

Factors to consider

There are several factors to consider when it comes to choosing the right type of industrial air compressor, including the obvious, which is the type of job it’s needed for. However, there are several other considerations to weigh up, including whether you need a compressor that’s stationary or mobile, or oil-free or lubricated. Choosing the wrong air compressor for your facility can lead to production issues or increased costs due to wasted energy, so to make the decision easier, we’ve weighed up some of the factors to consider in more detail, below.

Stationary or portable

As you might expect, stationary air compressors are not designed to be moved around, so they tend to be much larger and heavier than their portable counterparts. They’ll also have far larger air tanks and more powerful engines, making them suitable for larger jobs which require more power. However, their prices are much higher than portable models so they can be out of reach for some smaller companies. If you require a powerful compressor for a one-off job or short period of time, consider air compressor hire or a used compressor if a new model is out of your price range.

Portable compressors are designed to be moved around, with many including in-built wheels so that they can be easily moved from job to job. This is highly convenient and can allow you to complete several smaller jobs with ease, and they’re much more affordable too. However, they generate far less power so simply won’t cut it in a larger factory or production line.

What size do I need?

Correctly selecting the right size compressor is often one of the biggest challenges and this will depend on the application and usage that’s required. The right size also depends on the amount of pressure needed and the right air flow for your compressor and these are the two key elements that need to be considered.

Pressure can be measured in pounds per square inch (psi), or bar (metric measure of pressure) and you’ll need to make sure that the compressor can generate enough pressure to complete the task at hand. For example, if you need 100 psi to move or power a piece of equipment, anything less simply won’t do the job, so check how much pressure each size compressor can generate. Compressors can be classified according to the amount of pressure delivered:

  • Low-pressure air compressors (LPACs), which have a discharge pressure of 150 psi or less
  • Medium-pressure compressors which have a discharge pressure of 151 psi to 1,000 psi
  • High-pressure air compressors (HPACs), which have a discharge pressure above 1,000 psi.

You’ll also need to consider air flow; put simply, the right air flow means that the compressor can continue to perform the task at hand within an acceptable time frame. Most manufacturers will include data sheets stating the total air flow, but as a general rule – the larger the compressor, the larger the air flow.

Oil-free or lubricated

This will depend on your industry and its needs, but if the consequences of potential oil contamination are too risky, you’ll need to choose an oil-free air compressor. It’s more common to see lubricated (oiled) compressors, especially in manufacturing or industrial workshops, but places like a food production would choose an oil-free model, as the contamination risk would have far more serious consequences.

Oil in air compressors is utilized to lubricate, seal and also cool the compressed air and it tends to be a more economic option, too. Unless you do work in a sensitive industry (such as food production), the general advice is to choose a lubricated compressor for the reasons listed above. Oil-free compressors are also much more expensive and coalescing filters can be used to remove traces of oil from the air in lubricated machines.

Air Supply UK: The specialist compressor company

If you’re in need of high quality air compressor products for your business, get in touch with the experts at Air Supply UK. With over 25 years in the business, we’re proud to have built a reputation for reliable products and unbeatable service, and we offer a wide range of affordable used stock for our many customers, too.

We stock a variety of compressors (including screw compressors and reciprocating air compressors), alongside the repair and maintenance services you need to ensure your equipment is always in the best condition possible. For more information about any of our products or compressor services, give us a call today or visit our website.

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