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The Ultimate Air Compressor Purchasing Guide for Auto Shops and Mechanics

Two Champion air compressors side by side

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.

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.
Piston Air Compressors vs. Rotary Screw Air Compressors

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. 

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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. 

We have a large commercial air compressor selection for your auto shop and can give you insight into each one’s specifications and best applications. Request a quote today to get started.

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