As an independent auditor of compressed air systems, I am often asked to recommend a vendor or manufacturer in the selection of air compressors. Since there is no unbiased answer to that question, I would like to share with you some insights that I pass along to my customers.

1. No vendor makes the perfect compressor for all applications

Compressor selection can be as personal as purchasing a new vehicle.

Most people have an idea of what vehicle they would like, such as a truck, car or SUV, and some even have an inclination as to what manufacturer they have always liked. But most people like to shop around to see what else is out there, kick the tires and see what the asking price is.

No manufacturer makes the best or most suitable vehicle for every application, and the same is true with air compressors.

2. Know how much air you need

There are two ways to determine the volume of air required. One is to insert a flow meter into the air line downstream of the dryer. There are a few flow meters that have significant accuracy and ease of installation, creating great values for the price.

Many of these come with LED displays, but it often best to purchase a data logger for approximately $100-$150 that will record your air usage over time. These are relatively simple to install, and the flow meter or the data logger company can help you with this connection. This will reveal the peaks and valleys required to properly select and size the air compressor.

The second way to determine flow is to measure the kilowatts the air compressor consumes. Many electricians have the ability to record the consumption for you if you do not have the capability in-house. These electrical recording can then be compared to the published CAGI data available for that specific compressor.

3. Examine your facility pressure

The pressure leaving the compressor room and the far end of the facility should not differ by more than a pound or two. By installing pressure gauges that are fairly close to being matched for accuracy, you can communicate with another person at the far end of the air line to synchronize pressures.

If the pressures vary, it may be prudent to hire someone to examine the air lines to determine correct sizing. This is not a major engineering feat, but it may take time to determine the most cost-effective solution rather than repipe the entire facility.

4. Newer air compressors are similar to the newer cars being sold

They require routine service and fewer major overhauls. The service is essential to prolonging the life of your air compressor and maintaining it in tip-top shape. The response has to be fairly quick and the costs reasonable.

Network with other businesses in the area, and ask the vendor for references to determine if your prospective choice meets your standards. Ask if they have had good results with the model and size they proposed.

Every air compressor manufacturer makes good compressors, but like cars, there are some models they really hate to sell but do because they don't have another option to offer. Do your homework and avoid these.

5. Purchase cost has little to do with compressor selection

In many instances, it costs more to electrically power the air compressor in the first year than to purchase it. Look at the data from your prospective vendor's choice of the compressor he or she has selected and compare your air consumption profile to that specific compressor's energy consumption.

Is it large enough to handle your maximum load? Is it small enough to be efficient at the minimum load? Are you planning to expand your air requirements? If so, how would their compressor selection anticipate that potential increase?

It is always cost-effective to defer purchasing an additional or larger air compressor until you need it. Be candid with your vendor, but don't buy a 1,000 horsepower air compressor when you need only a 500 horsepower unit. It will cost you more to buy and may not be efficient at your low levels of air consumption.

6. Get the total price

Some vendors make up for losses in their sales price through delivery, installation, parts and service.

Purchasing an air compressor can be intimidating, but if you do your homework upfront, it can be a rewarding experience, save your company money and allow you to rest peacefully when you go home.