What Size of Compressor Do I Need?
One of the biggest challenges is to correctly size your new air compressor. Like to everything else, new compressors available on the market today are more efficient and employ better technology than their predecessors. This means that it's essential to understand the application and usage details in order to size the machine correctly. Choosing the wrong air compressor for your facility can lead to problems with production and or increased costs due to wasted energy.
How to Size an Air Compressor
Determining the right size of an air compressor involves a few essential steps:
- Identify Your Tools and Their Requirements: Make a list of all tools and equipment that will be using the air compressor. Check each tool's CFM and PSI requirements.
- Consider the Duty Cycle: Assess how often and how long each tool will be used. Continuous operation tools will need a compressor that can handle longer duty cycles.
- Account for Future Expansion: Think about any potential future tools or increased use. It’s wise to choose a compressor that can handle more than your current needs to avoid outgrowing it quickly.
Want to know more about Airflow, Pressure, Applications, and Power? In the following section, we will explain what each of the compressor selection criteria means and answer some questions you might have.
Compressor Selection Criteria
Selecting the appropriate compressor involves considering several criteria:
- Airflow (CFM): Determine how much airflow (cubic feet per minute) is required for your applications. This is a critical factor as it indicates the volume of air the compressor can deliver. Different tools have different air tool CFM requirements, making it essential to understand your specific needs.
- Pressure (PSI): Identify the necessary pressure (pounds per square inch) for your tools and machinery. Various applications will have distinct PSI needs.
- Application: Consider the specific applications and air quality requirements. Take into account any pressure loss due to dryers, filters, or drains. This includes evaluating whether you need a high-pressure compressor or one suited for spray painting or other specific tasks.
- Power (HP/kW): While important, power is not the primary selection criterion. Focus on airflow and pressure first, and then match the compressor’s horsepower (HP) or kilowatts (kW) to your needs.
Understanding Air Compressor Capacity and Flow Rate
When sizing an air compressor, it’s essential to understand the difference between capacity and flow rate.
- Air compressor capacity refers to the total volume of air the compressor can hold, typically measured in gallons or liters.
- Air compressor flow rate measures how quickly the compressor can deliver air, usually in CFM.
Both metrics are crucial for ensuring your compressor can handle the demands of your tools and applications.
One method to determine total flow is to consult equipment manufacturers for data sheets. However, the most accurate way is to conduct a “compressed air audit” performed by a compressed air sales professional.
Understanding the flow and pressure (a.k.a. cfm and psi) requirements for your facility is key when choosing an air compressor. Pressure and flow are two very common terms used when discussing compressed air systems.
Pressure can be measured in pounds per square inch (psi), or bar (metric measure of pressure). To think of this in simpler terms, pressure refers to the amount of force needed to perform certain amount of work at any given point in time. A simple example of pressure and how it works, is to imagine moving a wooden block across a table. In the illustration below, it shows that using 75 psi of compressed air is not enough force to move the block, but 100 psi of pressure has the ability to move the wooden block the desired distance.
The air compressor has to provide enough pressure to perform a given task (in this case it was to move a wooden block). Per illustration below, if 100 psi is required to move the block, anything less than that will not accomplish the task. It is important to understand what pressure is needed in order to size the compressor properly, otherwise you will be faced with problems, similar to illustration below where lower pressure was not able to move the wooden block, or perform the job.
Want to learn more about the differences between psi, cfm, and horsepower? Find out here!
What is the right air flow for my compressor?
Airflow, also known as free air delivery (FAD), is measured in cubic feet per minute (cfm), liters per second (l/s), or cubic meters per hour (m³/h) depending on your location. Simply put, airflow determines how effectively a compressor can perform a task within an acceptable time frame. The required flow depends on the duration needed to complete a task.
For example, moving a wooden block a short distance every hour requires less flow and can be managed with a smaller compressor and a storage tank. The compressor cycles on and off, refilling the tank for the next task. However, the constant movement of the block necessitates a larger, continuous flow (higher cfm), thus a larger compressor. Insufficient flow means frequent breaks for pressure buildup, indicating an undersized compressor.
Rotary screw air compressors generally provide more flow per kW or HP than piston compressors.
Summary:
When sizing a compressor, consider the specific requirements of the job:
For accurate sizing of your compressor for new or existing applications, always contact a compressed air sales professional for an audit.
What Amount of Pressure Do I Need?
Understanding the flow and pressure requirements for your facility is key when choosing an air compressor. Pressure and flow are common terms used when discussing compressed air systems.
Pressure can be measured in pounds per square inch (psi) or bar (metric measure of pressure). Simply put, pressure refers to the amount of force needed to perform a certain amount of work at any given point in time.
For example, imagine moving a wooden block across a table: Using 100 psi of compressed air is not enough force to move the block. However, 115 psi of pressure can move the wooden block the desired distance.
The air compressor must provide enough pressure to perform a given task. If 115 psi is required to move the block, anything less will not accomplish the task. It is important to understand the required pressure to size the compressor properly. Otherwise, you may face issues similar to the illustration, where lower pressure fails to move the wooden block or perform the job.
Applications and CFM/PSI Requirements
When determining the right compressor, consider both the amount of compressed air flow (cfm) needed and the specific pressure (psi) required for the process. Different tools and applications require specific CFM and PSI levels.
Below is a chart with common tools and their requirements:
Applications |
CFM |
PSI |
Air tools |
CFM |
PSI |
||||
| Home Use | 1-2 | 70-90 | Airbrush | 0.5-1.5 | 20-30 | ||||
| Spray Gun | 4-8 | 30-50 | Nail Gun | 1-2 | 70-90 | ||||
| Spray Painting | 4-8 | 30-50 | Dental Equipment | 2-4 | 80-100 | ||||
| Sandblasting | 6-25 | 70-90 | Tire Inflator | 2-3 | 100-150 | ||||
| Various Power Tools | 3-10 | 90-120 | Impact Wrench | 3-5 | 90-100 | ||||
| HVAC Systems | 6-12 | 80-100 | Air Ratchet | 3-5 | 90-100 | ||||
| Refrigeration | 3-5 | 60-80 | Hammer Drill | 3-6 | 90-120 | ||||
| Automotive Assembly | 8-15 | 90-120 | Paint Sprayer | 6-7 | 30-50 | ||||
| Food and Beverage Packaging | 4-10 | 70-90 | Grinder | 5-8 | 90-120 | ||||
Common questions when buying a compressor
How much CFM do I need for an air compressor?
The CFM required depends on the tools or applications you will be using. Refer to the above chart for specific requirements.
What size air compressor do I need for home use?
For home use, the CFM and PSI requirements are generally lower. Typical applications include inflating tires, operating small tools, and spray painting. Ensure you match the compressor to your most demanding tool.
What size air compressor for spray painting?
Spray painting requires a compressor that can deliver steady airflow at a relatively low pressure. Generally, a compressor with 4-8 CFM at 30-50 PSI is suitable.
Other factors to consider
- Air Quality: Depending on your application, you might need oil-free or oil-lubricated compressors.
- Energy Efficiency: Consider compressors that have validated energy efficiency ratings to save on operational costs.
- Portability: Determine if you need a stationary or portable compressor based on your workspace and mobility needs.
- Noise Levels: Some compressors operate more quietly than others, which can be essential in noise-sensitive environments.
Find more helpful information in the "Guide to Selecting the Optimal Compressor for Your Needs" ebook or contact us for personalized assistance. Our experts are available to help you determine the best compressor for your operations.
Volume Conversion Calculator
A volume conversion calculator can assist in air compressor sizing calculation accurately. It helps convert different units of measurement to ensure the compressor meets your specific needs. Using this tool can simplify the process of determining the correct size.
Compressors come in all types and sizes. From massive machines that keep huge production plants running to the small versions that avid do-it-yourselfers are using, there is a compressor for everyone. With so many models to choose from, which one is the right compressor for you? This guide will help you in making the right decision for your business.
Would you like to turn to one our experts? They are happy to assist you in finding the optimal compressor.