There are no broad guidelines for choosing an air compressor for your drilling jobs. Your air needs are dependent on the type of rock/formation and the diameter and depth of the hole. 

One recommendation that applies to any drilling job is to find an air compressor dealer that can do more than just rent or sell a piece of equipment. Every dig presents its own challenges, and an experienced air compressor sales associate plus a strong dealer network will be able to answer questions, find the machine that best suits the job and deliver it in time to the jobsite. At the end of the day, who you choose to work with is going to be just as important as choosing the right air pressure and volume.

When Does a Drilling Challenge Require ‘Large Air’?

Typically, what dictates the need for large air (over 750 cfm) is the diameter and depth of the hole you’re drilling. A larger hole needs a greater volume of air to clean the cuttings away from the face of the bit, because the air disperses more quickly in a larger hole. 

For example, consider drilling a water well in a residential area. The hole might be 6  inches in diameter to a depth of 400 feet. You could drill that with the use of a single air compressor running 750 cfm at 300 psi.

That’s still considered a need for a large air compressor, but nothing compared to running a 72-inch cluster drill. With a hole that wide, even if the depth is 80 feet, you may need multiple 1,600-cfm air compressors, because of the amount of air dispersion.

Low Pressure vs. High Pressure Air Drilling

Air pressure needs are similarly dependent on the type of drilling being completed. If you’re running cluster drills, rotary drills or hammer drills (DHD) through hard rock, which is typical for foundation work, you need high pressure air of 200 psig and above. 

With the multitude of different air drilling applications, each job is unique. No two are the same. Sometimes one air compressor is sufficient, while other times more units are needed for multiple pressures and flows, as dictated by the makeup of the hole to be drilled. 

For rotary drilling, air pressure needs are usually lower, therefore we would more likely need to consider large air volume, low-pressure compressors, again depending on air volume needs. A dual-pressure machine can offer you the versatility to tailor your job to the various requirements of pressure and flow.

What to Ask Your Air Compressor Sales Associate

If you’re looking to buy, rent or lease an air compressor, and you know the specs that you need, it’s important to ask your dealers pointed questions about their level of support:

• How quickly can you get a field service technician to my jobsite?
• Can you provide someone on call 24/7?
• If I need you to replace a part or a whole air compressor, do you have others readily available in your inventory? 
• If I have a job in another part of the state, in another state or across the country, can you act as my one point of contact to get the machines I need when I need them?

The answers to these questions, and how dealers respond when something may go wrong, are what really differentiates dealers. Know the pressure you need for your drilling job and know the volume, but at the end of the day, choose and work with a dealer who can support what they sell. That is going to make all the difference in the world in the successful completion of your drilling job.