Ask Atlas Copco: Vacuum Pressure Range and Capacity

Ask Atlas Copco is a segment that discusses commonly asked questions about various compressor, vacuum, and blower technologies, processes and best practices. Today’s answers come from Greg Marciniak, product marketing manager for the industrial vacuum division.

When we work with a customer to determine their vacuum needs, we first ask a few key questions. What is the application? How wet or dry is the process? What capacity do we need? Asking these questions helps us figure out the best vacuum answer for the customer that will ultimately provide them with a sustainable, efficient and cost-effective solution. A first step in selecting a vacuum is determining operating pressure and capacity, but these terms can cause confusion when not properly defined.

Customers sometimes want to choose a vacuum based on the ultimate pressure. Though similar, ultimate and operating pressure are not the same and should not be used interchangeably.

Ultimate pressure is the highest pressure a vacuum can achieve. A good way to think about ultimate pressure is like the top speed on a car. While it demonstrates what the machine can do when pushed to the limit, it doesn’t tell you much else, like the acceleration rate or braking power. This may be useful information to know about a vacuum, but applications usually do not need to reach this ultimate pressure. Instead, operating pressure becomes a more important measure.

Operating pressure is the required pressure during daily operation. Operating pressure and capacity are two critical factors to consider when choosing a vacuum.

Capacity is another area of confusion for many operators. The capacity of a vacuum should be measured in actual cubic feet per minute (ACFM), not free air delivery (FAD). ACFM is a volumetric unit that refers to the actual gas delivery when taking inlet conditions under consideration.

Many times, operators ask what their capacity is based on the ACFM. However, a few things must be clarified before jumping right in and accepting the ACFM at face value. First, it’s important to find out if the ACFM is at the pump inlet or at the process itself. Second, it’s important to consider the ACFM requirement when the vacuum is at operating pressure.

Some customers may want to attain a certain capacity and pressure that are independent of each other, while others require a specific capacity at a given pressure. It is easy to achieve both of these, but you should always discuss those needs with your compressed air provider. The more detail you provide about your process requirements, the better your final vacuum solution will be.

When beginning your vacuum purchase, have these numbers ready to discuss with any potential compressed air providers. If you aren’t sure how to determine your requirements, let us know in the comments below or contact an Atlas Copco expert. We’d be more than happy to help you determine your vacuum needs and help you find the most efficient solution for your application.