Help! I Think I Need a Larger Industrial Air Compressor!

Uh-oh. Suddenly there seem to be more operator reports stating that tasks can’t be completed because the air-powered equipment isn’t supplying enough pressure to get the job done. When these problems arise and your maintenance team has ensured that it’s not related to clogged filters or other issues that can cause the air compressor to lose pressure or work overtime, it is a tell-tale sign that your air compressor is too small to meet the needs of your facility.

Perhaps the equipment powered by the air compressor is being used differently, maybe load demands have increased due to production changes or possibly the air compressor was incorrectly sized in the first place. Whatever the reason, an undersized air compressor can lead to insufficient airflow that negatively impacts productivity. Fortunately, right sizing to a larger air compressor or adding redundancy to the current air compression system will help restore adequate airflow and return productivity to its intended level.

Size Matters: Why Having a Properly Sized Air Compressor is Crucial

The importance of having a properly sized air compressor should not be overlooked. Air compressors should provide enough capacity to deliver air at a stable and efficient pressure and flow rate, while always meeting the needs of your facility – even during peak demand periods.

So, how do you know if the current unit is not the right size for your facility? There will be signs if the air compressor is under- or oversized. For example, if the air compressor is too small, there will be pressure drops that prevent air tools from working properly, low-pressure alarms will frequently be tripped.

Undersized piston air compressors may run 24/7, which leads to inefficiencies and overheating. Constant running will also result in maintenance intervals coming sooner than desired and, ultimately, the life of the compressor will be reduced.

Conversely, if your air compressor is too large for your facility, it will experience frequent loading and unloading. This means the compressor will start up, meet the demand, stop, realize demand is present and start up again. This constant start/stop cycle will lead to significant energy bills resulting from high energy consumption during start ups, as well as motor burnout and mechanical failures caused by wear and tear on the compressor due to recurrent on/off cycling.

How to Correctly Size an Air Compressor

If you find that your compressor is having these issues because it is not properly sized, it will become necessary to establish the size needed to provide adequate flow and pressure at the most energy efficient level. To begin, calculate the cubic feet per minute (CFM) that is required throughout the facility by adding the CFM requirements for all the air-powered tools and equipment that may be used simultaneously. It is sometimes recommended to add about 25 to 30% to account for high demand periods, potential leaks and occasional or unknown usage.

The next step includes calculating the required pressure, which is measured in pounds per square inch (PSI), for each of the tools and machines that operate via compressed air. While it may be tempting to pad this number, be cautious about increasing pressure beyond what is necessary as doing so will ultimately increase power bills.

Once flow and pressure demands are determined, consider how the system will be used throughout a full production cycle, including fluctuations in demand based on shift changes and occasional high-demand applications. As a general rule of thumb, to achieve the highest efficiency, normal demand should be about 65 to 100% of peak output offered by the compressor. For more detailed information on sizing an air compressor see How to Size an Industrial Air Compressor for Your Needs.

Upsizing Your Air Compressor

If, after performing these calculations, you determine that your compressor is indeed too small, it is likely that you will need to purchase a larger air compressor to avoid the complications associated with an undersized unit. If this is the case, you now know the appropriate pressure and flow needed to meet facility demand and can take this information to your supplier.

However, if purchasing a larger compressor isn’t possible due to plant layout or budget, consider adding redundancy. Low variations in flow and pressure demand may be adequately handled by purchasing a second or third compressor to provide back up for occasional high-demand periods. This allows the original compressor and a spare to cover typical and occasional higher demands, while the third provides back up.

If there is a possibility that demand for the facility and its compressed air needs may increase in the future, but you don’t want to select an oversized air compressor at this time, purchasing multiple smaller compressors as opposed to one larger compressor will maximize energy efficiency in the short term, but provide capacity to handle anticipated demand fluctuations in the future.

While determining the proper air compressor size and adding redundancy or upsizing to meet the needs of your facility may seem like a daunting task, having an adequate supply of compressed air will improve productivity and decrease associated maintenance costs and utility bills, which will go a long way toward boosting your bottom line. For help determining air compressor size or to inquire about adding additional capacity, please contact a specialist at John Henry Foster.