Auto shop owners and mechanics rely on air compressors as important components to run successful businesses. This essential tool is helpful in various applications, driving revenue while saving time. Various air compressor types and models provide high-quality air for optimal performance and exceptional results.

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This guide on how to choose a compressor for your auto shop discusses their role, common uses, different types, specifications and purchasing tips to ensure you're equipped with the knowledge to make the right choice.

Understanding Air Compressor Basics

Air compressors use stored atmospheric energy kept under pressure in a tank until it's released for its intended purpose. Two types of displacement occur internally within compressors to compress and store the air.

• Positive displacement: This displacement occurs when an internal chamber within the compressor sucks in air and compresses it. The chamber opens and closes, and once the compression cycle is complete, the air is pushed into a tank for storage. Smaller compressors like rotary-screw and piston air compressors use positive displacement to produce compressed air.
• Non-positive or dynamic displacement: This displacement involves impeller blades sucking air into the internal chamber. The spinning blades create energy that builds air pressure, producing large volumes of compressed air at high speeds. Turbocharged cars mostly use this form of displacement. Industrial and commercial industries use air compressors that require air at high volumes produced through non-positive displacement.

The Role of Air Compressors in Auto Shops

Auto shops use various air compressor types for different reasons. The most common application is the use of pneumatic or air-powered tools. Compressors are required for automotive repairs to deliver adequate airflow when in use. For example, painting a car with an air compressor system can help restore the vehicle's appearance.

Some other common uses in the industry include:

• Inflating car tires to maintain optimal air pressure. 
• Pressure-washing cars and relevant parts like the engine bay.
• Sandblasting cars to remove paint and rust for a smooth, clean surface.

Types of Air Compressors 

Air compressors used in auto shops include piston or reciprocating air compressors and rotary screw compressors.

Piston Compressors

Piston air compressors use positive displacement to operate. The system works with valves and valve discs. Air is drawn into the cylinder as the piston moves downward so air can pass through. This process compresses the air that flows in, and the larger disc then moves to allow the compressed air to be used once stored.

The compressor is powered with diesel gas or electricity. The advantages of piston air compressors include being less expensive and requiring minimal maintenance.

A piston compressor's air volume, tank size, air pressure and horsepower can give you further insight into whether it's suitable for your needs.

• Cubic feet per minute: Varies in ranges based on requirements.
• Tank size: Varies based on requirements. 
• Pounds per square inch: Usually measured at around 125 pounds per square inch.
• Horsepower: Usually measured at around 15 horsepower.

Rotary Screw Compressors

Rotary screw compressors also use positive displacement for compressed air production. Two rotors produce compressed air as they rotate. If the compressor is dry-running, the rotors align precisely with a timing gear's input. If oil-flooded, lubricating oil closes the gap between the rotors in drive air compressors. The seal that forms allows energy to flow between the rotors, which produces compressed air.

The rotors are driven in one of three ways:

• Belt drive 
• Gear drive
• Direct drive

The main advantages of rotary crew compressors include a longer life span, continuous airflow, consistent high-pressure air supply and quieter operation.

Rotary screw compressor specifications vary depending on whether it is dry-running or uses oil, but here's a general idea of what to expect in terms of specifications:

• Cubic feet per minute: Varies based on requirements but can be 30 cubic feet per minute or more.
• Tank size: Varies based on requirements. 
• Pounds per square inch: Varies according to compressor type but ranges from 100-145 pounds per square inch.
• Horsepower: Usually measured at around 10 horsepower or more.

Selecting the Right Kind of Air Compressor for Your Auto Shop

Your shop's demand and workflow dictate the tools you'll need. High-output workshops require one or more heavy-duty compressors to match the pace and turnover rate. Choosing the right type of air compressor comes down to a few factors.

• Single stage: The most common compressor in smaller, less busy workshops, a single-stage compressor draws air in by one piston that moves down and compresses the air when it moves up and out the other.
• Two-stage: Used in factories and more extensive workshops, two-stage compressors possess two chambers that compress air by water-cooling the engine. 
• Variable speed: Fixed-speed compressors maintain air pressure consistently while variable speed changes to match the compressor's production rate to meet the airflow demand.

What Size Air Compressor Do You Need?

Air compressor sizes vary according to the type and requirements. The tank size capacity is the main indicator based on the various applications. For example, a 120-liter tank is suitable for smaller workshops, while a 240-liter tank can produce twice as much air compression in larger workshops.

Purchasing a bigger compressor may or may not be ideal for your business based on its size and can save or cause you to spend more money. Larger compressors use more electricity and are expensive to service, so consider if a smaller option could suit your needs.

What to Look for When Buying a Compressor

Choosing a suitable compressor for your workshop requirements is essential, as you want your investment to count. Here are some quick checklist reminders to note as you shop around for an air compressor:

• Check that the specifications meet your requirements.
• Match the price with the specifications to see that they align. 
• Ensure you can use and store the compressor properly and safely in your shop. 
• Account for service and maintenance costs throughout the compressor's life cycle.

Partnering with the right supplier is imperative, especially considering the after-sales services you'll likely need. Be sure to work with a reputable distributor to ensure you receive quality service and can access important features like warranties and protection plans. 

Choose Liftnow for Reliable Air Compressors

When making an informed decision regarding the best air compressor for your business needs, the size, specifications, type of compressor and supplier impact your choice. Liftnow's team of experts is available for advice on any air compressor questions or concerns to help you decide on the best one to suit your requirements. 

Air Compressor Buying Guide

Last updated August 28,

Air compressor power tools, also called pneumatic tools, are generally faster, lighter and more powerful than traditional power tools. They use a concentration of air to power the tool. The key to choosing the best air compressor is to match the unit to the job demands. Portable compressors are ideal for the home and the job site. Stationary compressors provide the high volume of air needed for powering automotive and production air tools. Use this buying guide to find out what to consider when selecting the best air compressors for your projects.

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Table of Contents

1. Types of Air Compressors

2. Electric Air Compressors

   Comair supply professional and honest service.

3. Gas-Powered Air Compressors

4. Cordless Air Compressors

5. Air Compressor Performance Ratings

6. Air Compressor Tank Size

Types of Air Compressors

There are two types of air compressors: portable and stationary.

• Portable air compressors come in a variety of shapes and sizes. Smaller models are light enough to carry. Larger models include wheels for mobility. Portable air compressors are available with tanks in different sizes, ranging from two gallons to 30 gallons.
• Designed to be bolted into a fixed area, stationary air compressors attach directly into a building's electrical circuit. They typically feature 60 to 80-gallon tanks and offer motors that are between 4 and 10-horsepower. They are a great investment for a garage or workshop.

Whether portable or stationary, the best air compressors are available in one or more power sources: electricity, gas or a battery pack.

Electric Air Compressors

Easy to use, electric air compressors simply plug into a regular wall outlet. Most run on standard household voltage, between 110V to 120V. However, compressors with motors that exceed 2HP can require a 220V to 240V outlet.

Electric compressors are the ideal choice if you need a quiet air compressor or a automatic start-stop air compressor. Since electric compressors don't emit fumes they are perfect for areas with limited ventilation. This makes them the best home garage air compressor.

Tip: Powering an electric compressor with a generator can damage the motor.

Gas-Powered Air Compressors

Gas-powered air compressors are usually portable and work well for those places where there's no electricity. They are commonly found at job sites, on farms or other outdoor spaces. The high-pressure output of a gas-powered air compressor makes it ideal for heavy-duty projects and tools such as nail guns, sanders and paint sprayers. These types of air compressors are more budget friendly but have fumes and can be noisy.

Cordless Air Compressors

Compact and lightweight, cordless air compressors use a rechargeable battery platform. Since there's no cords to get in the way, cordless air compressors are easy to carry around and use. This makes them ideal for projects that require more flexibility such as working on a roof or in small spaces.

Cordless air compressors are quieter and work equally well indoors and out. However, due to their limited power, even the best air compressors of this type work better for smaller projects than for larger ones.

Air Compressor Performance Ratings

Compressors generally have horsepower ratings between 1 1/2- to 6 1/2-HP. However, it's the standard cubic feet per minute (SCFM) or performance rating that reflects the air pressure a compressor generates inside its tank. A tank's SCFM determines just how much power the compressor will provide to a tool. This power is measured in pounds per square inch (PSI). In addition, the tools powered by air compressors also have their own SCFM ratings that indicate the air flow or pressure a tool needs for top performance.

Here's how to gauge the minimum compressor SCFM rating you need for your air compressor:

• Examine the SCFM requirements of all the tools you intend to use.
• Multiply the highest tool rating by 1.5 to get the minimum compressor SCFM for your needs. Since actual SCFM varies during compressor operation, this number will give you a little buffer.
• If you expect to operate multiple pneumatic tools at the same time, you'll need more power. Calculate the minimum SCFM compressor rating by adding up the SCFM requirements for each tool that you'll use simultaneously.

Smaller tools usually require 0- to 5-SCFM. Larger tools can require 10-SCFM or more.

• Most light-duty home compressors are designed to power only one tool at a time. Light-duty compressors generally have 90-PSI, which is typically sufficient for powering pneumatic tools for simple, household tasks.
• More powerful, professional-grade compressors may generate 150-PSI or higher and can handle multiple tools.

Air Compressor Tank Size

A smaller tank size is a good choice if you intend to use a tool intermittently. For example, tools that require only quick bursts of air drain the tank much more slowly. For tools like pneumatic brad nail guns or finish nail guns, a 2- to 6-gallon tank is sufficient.

If your pneumatic tool requires a high volume of continuous air, then you should consider a larger tank. It's best to have a large enough tank with a compressor pump that exceeds the SCFM requirement of the tools. This will allow the compressor time to cool between cycles.

Air Compressor Pump Type and Features

There are two air compressor pump types: single and two-stage. You can also choose between oil-lubricated or oil-free. In addition, there are other pump features that can protect both you and the compressor from harm and unnecessary wear and tear.

Below are the types of air compressor pumps you can choose:

• Single-stage air compressors can have one or more cylinders producing compressed air at the same output pressure.
• Two-stage air compressors. The first-stage cylinder(s) feed air to a second-stage cylinder that further compresses the air. The second stage cylinder(s) typically increase the tank pressure to around 175-psi. The benefit is more air stored in the same size tank, allowing tools to run longer. This is useful for high-demand work, such as continuous tool operation in an auto shop.
• Oil-lubricated air compressors require oil to operate, just like a car or lawn mower engine. The oil lubricates the moving parts in the pump to prevent excessive wear. They are generally larger and heavier than oil-free models. Plus, oil must be monitored and changed to prevent premature failure.
• Oil-free air compressors typically use special piston rings. These rings are made from a material like what's used in non-stick frying pans and to lubricate the cylinder. Oil-free compressors are a much smaller, light and a popular choice for both homes and job sites.

Best Air Compressor Accessories

Once you've discovered the best air compressors for home use or workshop use, it's time to add a few key air compressor parts and accessories:

• Installing a pressure regulator on your air compressor will help you know precisely how much air flows from the compressor. You can easily adjust the pressure up or down according to the needs of the job.
• Trade out the air hose with a longer option for extended reach.
• Adding a desiccant dryer to the air compressor protects your equipment from the moisture contained in compressed air. Moisture can cause damage to pneumatic equipment over time.
• An air filter protects pneumatic tools from water, oil and dirt as you're using the air compressor.
• Air compressor combo kits include an air compressor with key accessories or a compatible pneumatic tool.

Air Compressor Features and Safety

When deciding between different types of air compressors, look for features like:

• An air-cooling system that cools pumping machinery and extends motor life.
• A thermal overload switch which automatically shuts off motor if it overheats, increasing tool life.
• A label stating that the unit meets the standards of the ASME (American Society of Mechanical Engineers) for high-quality materials and craftsmanship.
• A roll cage that protects the compressor from being crushed or battered on the job site.
• Air compressors with universal quick connectors make it easy to trade out tools.

After you've chosen the best air compressor for your needs, keep it performing well with these tips:

• Never exceed the recommended pressure for the job or the tool.
• With oil-lubricated compressors, always check the oil level to ensure sufficient lubrication.
• Make sure safety relief valves are not covered during use. Otherwise, air will escape automatically if the pressure is too high.
• After each use, open the drain to get rid of any moisture that's accumulated.
• Always consult your owner's manual for specifics.

Now you understand how to choose the best air compressor for your pneumatic tools. Start exploring accessories and extra features to make your projects even easier. Ready to choose a portable or stationary air compressor? Use The Home Depot Mobile App to locate products and check inventory. We'll take you to the exact aisle and bay. Just need the best air compressor for one project? Consider tool rental to get your project done. Use a rented tool and then bring it back. There's no maintenance required or storage needed.

For more information, please visit High Pressure Air Compressor.