Compressor Sizing

It seems many folks buy an air compressor without considering compressor sizing. What they intend to use the air compressor for, or how big an air compressor they are going to need to provide adequate compressed air to run their air tools and compressed air using equipment?

For compressor sizing it is necessary to figure out how much air you're going to need. That is... the air requirement for all the air tools, all the blow guns, all the air cylinders, all the air operated diaphragm pumps, all the everything that is in your plant or workshop that uses (or has the potential to use) compressed air and whether or not that compressed air demand is going to be constant, or change as your tool use changes, production using air equipment increases, and so on.

Compressor Size Matters

There is lots of additional information about compressor sizing on this page. As well, the comment form at the bottom of the page invites you to ask a question about compressor sizing, or make a suggestion to help others.

To Help Compressor Sizing Here Are
        Simpler Blocks Of Information

When first venturing into the air compressor-sizing arena, folks tend to be more than a bit intimidated. There's such a vast array of compressors, of types, of capacities, with a veritable feast of accessories; it's easy to become confused!

And, though there are many manufacturers of compressors world-wide, all are focused on selling their own products, which may impart a certain bias to the information that's available from them about their compressor-sizing, you think?

What's The Air For?

Have you determined what you'll be using compressed air for? In order to correctly size your compressor, you really must do some homework towards figuring out the volume of compressed air you will require. Here you will find a list of compressed air uses that may affect your overall compressed air requirements.

The above link you may have just visited took you to a short list of some in-plant compressed air applications, this to help you determine which of those you have or are planning to have, equipment that will be consuming your compressed air and needs to be accounted for when compressor sizing.

Is Air Use Quantity A Total Or Periodic Demand?

If it is necessary in your plans to run all of those compressed air using appliances at the same time, and for long periods of time, then you are going to require a much bigger compressor than if they are used intermittently and sporadically.

If your compressor is for continuous air use then start making a list of everything in your plant that uses air, and leave a space beside each to note the expected CFM demand for each. Better yet, use a spreadsheet so that the air consumption numbers can be set up to give you a running total of the air you'll need.

Know that compressed air consumption of tools varies depending on the size of the air tool, it's speed, and the efficiency of that air tool. You need to get the specific compressed air demand for that air tool from the manual or the manufacturer of the tool for accurate assessment of the overall compressed air demands of your shop.

You may find the chart below handy in approximating the CFM requirements of an assortment of standard air tools. This is a guide only. Your actual consumption of compressed air will vary, depending on your tool size and design.

Air Consumption Chart

Air Tool Consumption

Air tool consumption changes based on variables. Grinders will have changes in consumption due to grinding wheel size, and rotary sanders will have their consumption change due to the pad size. Even the same tool from two manufacturers will have different air consumption rates.

Try to get the air consumption figures for a specific air tool from that tools booklet / manual, a label on the tool, or from the manufacturer! If contacting the manufacturer, have the model number and serial number of the air tool at hand.

Consider "factoring in" the highest air consumption figures you find for the tools you expect to use. You may oversize your air compressor capacity by doing so, but under sizing the compressor you purchase may bring greater long term costs to your plant as you grapple with air tools or air cylinders that do not run as expected due to a lack of compressed air supply.

Other Air Use

Air tools are only one of many applications in a plant that consume air. It's necessary to give consideration to all of the ways that you will consume air in your plant and applications.

Some folks don't consider an air-driven blow gun as an air tool, yet these can sometimes use more compressed air than expected.

Air driven automated production machinery can consume far more air than some air tools as air operated production equipment with valves, air cylinders and other air actuators is often run for 2 or 3 shifts per day, with uptime measured in weeks. Each piece of equipment may have dozens of air actuators or air cylinders operating at high speed.