Compressor Selection Guide

The Air Compressor provides the life blood to any vehicle maintenance facility, whether you perform simple maintenance, large overhauls, wheel work or body work. The compressed air circulating through your shop powers the tools and equipment your facility needs to perform its daily work. So, it is important to select the correct type and size for your facility. It can be difficult because there is not an exact science to choosing the correct size or style, but here are some great guidelines you can follow as you work through your compressor selection process. We will go through the 2 types of compressors used in vehicle repair and body shops. Also discuss the 4 best questions that should be answered to zero in on the right fit.

Compressor Selection Guide: Types Overview

The two most common types of compressors used in repair and body shops are reciprocating compressors and rotary screw compressors.

1. Reciprocating compressors (also known as piston machines) are the most used compressors in the automotive world. It uses method of positive displacement with a back-and-forth motion of pistons to create pressure and compress surrounding air. The air is then stored in a storage tank usually attached to the compressor or close by. They run in a stop start configuration. Meaning they turn on when there is a demand for air and turn off when the air system and storage tank is full.
2. Rotary Screw compressors are another option that continue to grow in popularity. They also create positive displacement, but produce air using two tightly meshed rotors and trap air in between as they rotate pull the trapped air through and reducing the volume. The air is then stored in a tank or goes right out into the system.

Both types of compressors come with advantages and disadvantages. Here are the side-by-side comparisons. 

Now that we have explored the 2 types of compressors, we can now talk about the 4 questions you want answers to prior to deciding on the size. 

Compressor Selection Guide: Sizing and Selection Questions

1.       How much air does your shop require?

This seems like an obvious question, but it is not always easy to answer. Like we discussed in the beginning of the article there is not exact science to match air demand with the exact compressor. The best way to approach this question is find out what tools and equipment run off air. Everything that runs off air has a SCFM (standard cubic feet per minute) rating or requirement. Make a list of all tools and equipment that run off air and their SCFM rating. Add all the SCFM requirements together, factor in possible growth (up to 25%), and that is what your maximum requirement is. Keep in mind that not all tools and equipment are always running. Look at the list and see which tools you are running the most. 

2.       How much air pressure do you need?

Once you have established how much air is needed, you now need to figure out how much pressure your facility requires. Much like SCFM rating, each tool and piece of equipment has a pressure rating measured in psi (pounds per square inch). Check the requirements again of all your tools and equipment and see what your highest psi requirements are, and the psi requirements of any tires you will be filling if you are doing wheel work.

3.       What are the electrical requirements?

Compressors have specific requirements for phase, amps and volts in order to run the compressor properly. When ordering your compressor there may options on the motors you can choose for the compressor. It is important you know what type of power you have running into your building and what your electrical breaker is set up for. Once you decide on a type of compressor and size you can make sure it will match your current electrical to your building or make any upgrades prior to having the compressor installed.

4.       Where is the compressor being installed?

Whether you are installing a compressor into a new area in your building or replacing one in an existing building it is important to consider the environment you are going to be installing it into. Location questions you might want to consider are:

• Is it being installed in a well-ventilated area or temperature-controlled environment? Compressors need proper ventilation since they can produce a lot of heat. They will be using the surrounding air to generate compressed air. Also, if put outside in a shed you may be exposing them to extreme heat or cold depending on the area of the country you live in.
• Are the dimensions of the area you going to install it in large enough to leave space to service the compressor? It is important to leave enough space around the compressor for access for service and repairs. Also consider safety if you are planning on installing it on a mezzanine or hanging device.
• Is it being installed close to where people are working? This needs to be considered because of the noise it produces, especially a reciprocating compressor.

Compressor Selection Guide: Conclusions

We have reviewed the two most common types of compressors and the advantages and disadvantages to both. We have also laid out the questions that need to be answered to help choose the best size compressor. The next and final step is to talk to a equipment and service provider that will help guide you through this process and provide a quality piece of equipment with readily available parts. Remember your compressor is a vital tool that keeps your facility running. It is important to keep it on a regular maintenance schedule to keep it running smoothly. The cost of maintaining your compressor is minimal to the cost of facility down time and major component replacement or repairs.