Which Air Compressor Do You Need?

Estimated time to read: 4 mins

Wondering which air compressor is best for you? It depends on what you’ll be using it for. Different air compressors produce different amounts of compressed air. They also produce it at different operating pressures. In fact, piston compressors and screw compresses even do this using different methods. Looks like you have a lot to think about. Let us help you. 

The first question: How much compressed air do you need at your supply point? Do you have multiple supply points? You’ll also have to think about how you want the individual system components to work. Will they be operating one at a time? Will you have them all running at once? Find the right balance and estimate your overall air requirements. 

In the air compressor world, we usually talk about air flow using the term ‘Free Air Delivery’ (FAD). Depending on your location, FAD is measured in litres per second (l/s), cubic feet per minute (CFM) or cubic meters per hour (m3/h). 

The FAD will show you what size of compressor you need. The size has a big impact on the efficiency and longevity of your compressor. Underestimate it and the pressure will drop and, in some cases, even prevent the compressor from operating correctly. Overestimating it may lead to mechanical issues. Your compressor might even fail completely.

There are two ways to find out what your FAD should be. The first, easier way is to look at the datasheets for your equipment. Easy, huh?  

A better—but more complex—option is an audit of your compressed air system. You’re best calling on a professional for this. What if you’re not sure whether you need an audit? Contact ALUP for a helping hand and honest advice.

Different equipment operates at different operating pressures. And even compressors of the same basic size, with the same FAD, will produce compressed air at different pressures. Which means that to find the right air compressor, you also need to find the right operating pressure. 

Find out which part of your system requires the highest operating pressure. This is not actually the working pressure you want for your compressor. We recommend adding about 15–30 PSI or 1–2 to this number. (Pressure is usually measured in pounds per square inch – or PSI, the imperial measurement – or bar – the metric measurement.) Why raise the pressure? Basically, the pressure will drop as air flows through your drying equipment, filters and piping further down the compressed air system.

Wondering what would qualify as a low- and high-pressure compressors? Low-pressure air compressors are capable of supplying air at a pressure of 4-13 bars or 60–190 PSI. A high-pressure air compressor will put out air at pressures up to 400 bar or 5800 PSI, and sometimes even higher.

It’s easy to be overwhelmed by all the different types of compressors. The good news? In most cases, you’ll only need to look at piston compressors and screw compressors. And from here, your choice will depend on your workload and the consumption characteristics of your tools. 

Let’s say you offer tire services or run packing machines. You use compressed air discontinuously, in short bursts. And this means a piston compressor is probably the best choice.  

But suppose you need compressed air continuously. A screw compressor is the best bet.  

What if you have more complicated needs? Let’s say your system needs a continuous supply of compressed air, but you use it at irregular intervals. Does this mean you need a piston compressor or a screw compressor? Our recommendation? It sounds like you might be best using a screw compressor that has a variable speed drive ... But we would recommend contacting us to really discuss the finer points and pinpoint your exact needs.