What Size Pulley for Air Compressor? – Step By Step
The pulling sizing is complicated yet one of the most prime considerations one should put thought to. The size of the pulley is crucial for all the machines. Similar is the case of air compressors. You need to understand how important is pulley sizing when it comes to compressor rather than jumping onto what size does your compressor require. Therefore, we have laid out a background, signifying its importance. Have a thorough read to know it all.
Why is Pulley Sizing Crucial?
Pulley sizing has always been a crucial subject when it comes to air compressors and other machines that involve rotations. These machines employ the use of motor which needs proper rotations per minute. Without correct RPM, not only will you notice a significant decrease in efficiency, but also a decline in performance. This will affect the durability of the machine, decreasing its life.
In order to get you all a better idea, we proceed by explaining what RPM is. RPM is rotations of the motor per minute which is indicative of the speed. This determines the pump’s output flow. When it comes to an air compressor, we usually consider it in gallons per minute. More common units are, however, liters per minute.
Neglected pulley size has a high probability of being the wrong one. This will result in incorrect RPM. This in turn will have a notable and serious effect on the pump’s performance and efficiency. If the RPM is greater than what is needed, the air compressor will experience wear and tear of the moving parts. The parts include the motor, pump, and pulley itself. On the other hand, if the RPM is slower than what is needed, there will be a notable decrease in the pump’s performance, resulting in decreased efficiency.
This is the reason why choosing the right pulley size is important. No one wants to spend hundreds of bucks on an air compressor again and again. Therefore, utmost consideration and great care are required, specifically when it comes to selecting the pulley. It is strongly advised to follow the guide below to know the right size for your air compressor.
Pulley Sizing Math
The formulation to get the right size of the pulley for the air compressor is very complex and tedious. But don’t you worry because we are here to assist you. You can also get the right pulley size by dividing the speed in RPM of the pump by the speed in RPM of the motor. This greatly signifies the ease, making you get accurate pulley sizing.
Let us demonstrate this with some examples so that you get a better idea. For instance, if you have the 1500 RPM of the pump and the 2000 RPM of the motor, you can simply use the above formulation. The accurate pulley ratio in this case will be pump’s RPM/ Motor’s RPM which is 1500/2000=0.75. Isn’t this simple?
FAQ’s

How do I know what size pulley I need for my compressor?
In order to determine what pulley size you need for the compressor, you need to go through complicated, tedious mathematical formulations. This will tell you the appropriate pulley sizing in terms of the value. However, to get a closer idea, you can also do this simple math. This can be obtained by dividing the component that is driven which is usually the pump by the RPM of the motor. Next, you have to obtain a ratio of the driving component which is usually motor by RPM.

Does a smaller drive pulley increase speed?
The pulley size and speed have an inverse relation. In layman’s terms, the larger the size of the pulley, the smaller will be the speed and vice versa. Therefore, if a larger size pulley is turned by a smaller one, it will rotate will lesser speed than the smaller one as speed multiplied by the diameter is a constant value.
Another thing which you should be aware of is that a smaller pulley has a direct relation with power at the shaft. Therefore, a smaller pulley will have a smaller power whereas the larger one will have large power at the rotating shaft.

How do you choose a pulley?
Getting the right pulley is crucial, specifically when it comes to an air compressor. Therefore, you need to consider some factors when selecting the pulley. The three most important ones are
 The size of the motor and compressor
 Drive component and driven component
 Other important considerations include the chemical resistance, impact resistance, and noise produced.