Whether it’s a new plant or an existing facility, selecting a compressor can be a daunting task. 

That’s why it’s imperative operators understand the different benefits and challenges compressors offer before making a selection.

Here are some things to consider when determining what system is right for your facility:

Size vs. type vs. features

You’ve determined the need for a compressor. Now you need to understand which processes need air, how much air and at what pressure.  

If you are starting new, consult with a sister plant or a similar plant size. See what works for them. You can also start by looking at how much air different machines need and when you will be running them. Most likely, you won’t be running every machine at the same time.

If you are optimizing your current plant, an air system assessment (sometimes referred to as a compressed air audit) will help determine a plant’s demand profile. This includes how much compressed air you are using, how much extra capacity you currently have and how plant demand changes over different shifts and days of the week. This study will help you understand what size compressor you need and if some applications would benefit from additional features. For example, if the application needs bursts of air every 15 minutes, a compressed air tank would help with this one application. 

Additionally, if you have two or more compressors and they aren’t cycling correctly, a master controller can help the compressors communicate with each other as well as the other compressed air equipment to determine if each component is functioning properly. 

Next, take a look at the layout of the current compressors’ location. Is it in a compressor room or just the back corner of the plant? For reliable and efficient performance, consider room ventilation, equipment clearance and the overall compressor room environment. Will the compressor fit with clearance for service work? Is the compressor away from processes that produce a lot of heat? Where will the inlet air and discharge ducts go? Will you need to purchase any add-on parts like a cooling water tower that could potentially take up more space? Is there enough ventilation?

Speaking of ventilation, air-cooled compressors require a significant amount of cooling air for the inlet and require enough room for the discharge. Is the compressor room near the boiler room, or situated near an area of the plant that gives off fumes? 

In rare cases where the compressor is in an area without cool, clean air, a water-cooled compressor may be the most ideal option. Otherwise, improper or inadequate ventilation can lead to equipment failure, issues meeting temperature regulations, and ultimately, plant downtime.  For water-cooled compressors, the better the water quality, the longer the lifetime of the compressor heat exchangers. Does your plant already have a closed loop cooling system on-site? You could tap into the existing system for the water-cooled compressor. If not, the initial cost for the cooling system as well as the cost for the water and water treatment would need to be considered. After factoring in these costs, an air-cooled compressor may be considered more cost-effective. 

Also, look at your piping. Is it large enough to accommodate the volume needed? Pipe diameter significantly impacts flow and pressure. Often, plants are using 15- or 20-year-old black iron pipes and the inside diameter is narrowed, causing significant pressure drop. It may be time to replace piping. If so, plan for the future and size the pipe for future expansion. It’s far easier and less expensive to add compressors to a system than it is to increase pipe diameter. 

Likewise, do you have stringent requirements you need to meet? Oil-free compressors are an option, but oil-injected compressors could also help you meet these requirements with the proper air treatment. 

“One thing we have noticed is more customers leaning toward our custom-engineered solutions,” says Jarno Manzke, technical director for Kaeser Compressors, Inc., Fredericksburg, Va. “The custom engineered solutions are custom enclosures that are built to specification and host the entire compressed air system in a custom enclosed skid. They are built in our Fredericksburg plant, and arrive to your facility ready to be piped into your existing compressed air piping.”

These custom-engineered solutions eliminate space, weather and accessibility constraints, and greatly reduce construction and installation time. They are customized to your plant’s needs, and can be a solution for plants needing more space or a cleaner environment for the compressor.

Calculate the cost

When determining which compressor is right for your facility, operators need to consider the applications, cost of electricity and space. Another consideration is backup. Can you afford for your plant to be down if the compressor is down? How much money would you lose if your compressor is down for 1-3 hours? Two smaller compressors are often a better option than one large compressor, and provide the backup air needed when one is down. 

On the other hand though, users should consider the heat recovery potential by using the cooling water to pre-heat a plant process. This may offset the additional cost of the cooling water and swing the solution in favor of the water-cooled compressors. 

Keep in mind, there are also space heating opportunities with air-cooled compressors, but this is typically only available seasonally. 

It’s also important to note the difference between buying new vs. used compressors. Before making a decision, calculate the price and its long-term costs associated with the purchase. Most manufacturers can provide you with a system simulation to show multiple scenarios and the energy savings potential. What is the return on investment? What is the annual energy costs?

Scope out suppliers

There are several manufacturers of compressed air equipment. And, each has different distributors who provide local service.  

Talk with different suppliers to learn how they do business and how buying the process is. Do they offer complete installations? Can they perform air assessments? Does the supplier provide maintenance or assistance outside of regular business hours?  

Consult with the Compressed Air and Gas Institute (CAGI), Cleveland, Ohio. CAGI developed a Performance Verification Program that verifies the information that participating manufacturers publish on the standard CAGI Data Sheets. 

Read up on customer testimonials and talk to others in the industry. Schedule booth visits at tradeshows to see the equipment in person and talk to a sales rep on the show floor who can provide additional information and answer questions. Building a relationship with the supplier speaks volumes as to the future of the compressor itself.