This is so important because of the amount of energy it takes to compress air. If the compressor is too large, you risk wasting a lot of energy (especially if you choose a fixed-speed model). And that will add a lot of unnecessary expenses to your operation.
If the compressor is too small, on the other hand, you will not be able to meet your demand. That is also why it is important to take into account any future expansion. By factoring in your future compressed air needs, you can avoid having to purchase another compressor again too soon.
But how do you properly size a compressor?
To determine the ideal size for your compressor, you should know your air requirement and working pressure.
The latter is measured in pounds per square inch (psi) or bar (metric measure of pressure). If you are unfamiliar with these terms, just think of pressure as the amount of force that is required to perform a task at any given point in time. To go back to our earlier example, it is the amount of effort you have to exert to push air from your mouth into the small opening of a balloon.
In order to complete the task without wasting energy, you want to make sure that you get the pressure just right.
The air requirement, on the other hand, refers to the total volume of compressed air you need. It is calculated as the sum of the air consumption of all tools, machines and processes that will be connected, and estimating their individual utilization factor by experience. In addition, you should also take into account leakage, wear and future air requirement changes when sizing the compressor.
If you are confident in being able to determine your own air requirement and working pressure, then you should calculate and periodically reassess it. However, if you need help with this task, do get in touch with an Atlas Copco representative, who will be happy to assist you.
When sizing a compressor, many users do not take into account the ambient conditions of where and how they want to set it up.
These include the elevation above sea level, ambient pressure and temperature, and humidity. Coolant pressure, compressor type and power source must also be considered.
All of these factors can affect the maximum working pressure, the compressor’s capacity, its power consumption and the cooling requirement.
The most important factor is the inlet pressure variations at altitude. For example, a compressor with a pressure ratio of 8.0 at sea level will have a pressure ratio of 11.1 at an altitude of 3,000 meters (if the application’s operating pressure remains constant).
Note that the ambient temperature, humidity and coolant temperature all interact and affect the compressor performance to different degrees depending on the compressor type.
