The duty cycle of an air compressor refers to the period of time the machine may be used for at 100 PSI and at a standard ambient temperature of 72° F, before it has to shut off.
The air compressor must maintain a consistent volume of air flow (CFM) and pressure (PSI) throughout its operational life cycle. For those who want to use their air compressor for an extended amount of time, this is a crucial factor to consider as the many types of compressors have differing duty cycles. In the majority of circumstances, an air compressor runs at a duty cycle of around 60 percent. In certain situations, larger compressors may have higher capacity ratings, sometimes reaching up to and even exceeding 100 percent for gas-powered units.
For more information, see our complete guide to what air compressors are & how they work.
How do you work out duty cycle?
One full cycle is defined as the amount of time it takes to utilise and refill the water tank.
In order to determine the duty cycle of an air compressor, run-time calculations must take into account the compressor‘s rest time, often known as the time spent off the job.
In most cases, the duty cycle is computed by dividing the compressor run time by the total time required for the cycle.
The duty cycle formula is as follows:
compressor runtime / (run time + rest time) = duty cycle %
How does air compressor duty cycle relate to CFM?
When choosing an air compressor, it is also vital to consider the CFM values, which are measured in cubic feet per minute (CFM), coupled with the duty cycle. Air compressor pump output is often used to determine CFM ratings, making it even more critical to understand the link between duty cycle and CFM.
It is necessary to multiply the compressor‘s CFM rating by the duty cycle % in order to determine the compressor‘s ability to provide CFM constantly rather than intermittently in order to determine its CFM capability. I’ll present you with a number of examples based on the usual duty cycles I mentioned earlier, and let’s suppose we have an air compressor with a capacity of 20 cubic feet per minute (CFM).
For more detail, see our article What is air compressor CFM?
Is air compressor duty cycle important?
The duty cycle should not be a significant consideration if you are a hobbyist who just does little chores at home, according to my perspective. Is it more likely that you use an air compressor on a frequent basis and in significant amounts? Perhaps portable compressors are more useful for you? When it comes to professional applications, where there is a significant need for speedy results, the duty cycle takes priority over all other aspects. When the air compressor is not in use, the operator stands the risk of losing money for every minute the machine is not in use.
What is 50 percent air compressor duty cycle?
Do you have any idea what it means to have a duty cycle of 50 percent? Following the manufacturer’s instructions, the air compressor runs for 5 minutes, or half the time, throughout a cycle of 10 minutes – therefore with 5 minutes of downtime. That is precisely what the fifty percent means.
A more straightforward way of putting it is that if your air compressor has a duty cycle of 50%, it will give you a runtime of 30 seconds each minute.
What is 100 percent air compressor duty cycle?
So, you’ll already know the answer to this one – yes, an air compressor with a 100% duty cycle can run continuously for an entire usage or duty cycle, be it 1 minute, 10 minutes or 1 hour, therefore giving you minimal downtime.
How frequently should a compressor cycle?
The number of times an air compressor cycles has a substantial influence on the overall efficiency of the air compression system. Allowing a compressor to run more often than the required duty cycle might result in the compressor wearing out more quickly. The number of times your compressor can cycle will be determined by the cycle time of the machine in question as well as the duty cycle rating of the compressor.
Your air compressor‘s cycle time measures how long it takes to load and discharge compressed air from a tank or container. It uses more energy when an air compressor operates at a high rate of rotation. When it comes to getting the most life out of your air compressor, it’s ideal to have a longer cycle time and fewer cycles per hour. Here are a few suggestions for increasing your cycle time and increasing the efficiency of your air compressor:
- Make use of a larger pressure band
- Increase the size of your storage tank
- The pressure between the primary storage tank and the compressor should be reduced as well.
How to prevent your compressor overcycling
Choosing the proper size air compressor will help to minimise the risks associated with over-cycling and the subsequent reduction of the system’s service life. The compressor you choose must be capable of working at a duty cycle adequate for your application while also fulfilling your PSI and CFM requirements for the duration of that duty cycle, among other things,
It is vital to remember that the duty cycle will also be related to a PSI and CFM for the provided percent of the entire cycle length, and that this should be kept in mind at all times. Consider the following illustration: 125 PSI and 25 CFM might be generated for the whole length of the compressor cycle by a compressor that claims a 100 percent duty cycle. When a 50 percent duty cycle is promoted for the same compressor, greater power at 150 PSI and 10 CFM may be achieved in half the time of the whole cycle length.
It may be advantageous for you to create a working connection with a dealer who can ensure that the model you choose is the most suited for your company’s specific needs.
How to extend the duty cycle of a compressor
If you need to run your compressor for longer than its rated duty cycle, there are a few ways that you can extend its runtime.
Use a larger air compressor. This will allow you to run more tools simultaneously and reduce the amount of time that each instrument is running.
Use a pressure regulator on each tool. This will lower the air pressure going into the device and will decrease the amount of air that the compressor needs to produce.
Install an after-cooler on your compressor. This will cool the air down before it enters the tank, which will help it last longer.
Use a lubricated or greasy rotary screw air compressor. Rotary screw compressors reduce the amount of heat build-up because they are continuously cooled with oil instead of ambient air like reciprocating compressors.
Install a belt guard on your electric motor to protect it from damage or burnout caused by dust and debris contaminating the belts and bearings inside the compressor tank.
Efficiency and duty cycle
Rotary screw compressors, which have spinning components that wear down over time, are only 25 percent efficient at 100 percent duty cycle and 12.5 percent efficient during continuous operation if there is no cooling system in place. Because of this, these sorts of air compressors are generally equipped with an after-cooler (to cool the discharged air).
Generally speaking, most electric motor-driven air compressors are approximately 87 percent-93 percent efficient at full load, which is why they are widely used in construction sites where traditional air compressors would be too loud, too hot, and/or too dangerous to work around on a continuous basis. The maximum capacity of these sorts of air compressors is normally 75-80 percent in continuous operation, however this may vary widely.
How different air compressor motors affect duty cycle
Although the duty cycle of continuous operating air compressors is great, the compressor motor itself can only work at full performance for a total of 30 minutes at a time on a continuous basis. After that time period has passed, the compressor will need to be shut off and allowed to cool before it can be restarted.
Using an electric motor-driven compressor without a belt guard or pressure switch for more than 30 minutes at a time constantly may cause the electric motor to overheat and fail prematurely. This is due to the fact that the majority of electric motors are cooled by air moving through their casing and over their windings and brushes. If these components get clogged with dirt and dust, they will be unable to dissipate heat effectively, resulting in overheating and eventual failure.
The usage of a belt guard on your electric motor, as well as the installation of a pressure switch, are both vital in preventing this from happening. If the compressor senses excessive heat or pressure, it will automatically shut down.
Rotary screw air compressors offer a longer duty cycle, although reciprocating air compressors are less energy efficient in general. Due to the fact that they are continually cooled with lubricant oil rather than air, they are more efficient than other kinds of compressors (scroll, reciprocating). Continuous-duty rotary screw compressors are capable of running continuously for up to 24 hours a day.
What is an intermittent duty cycle compressor good for?
An intermittent duty cycle compressor is a type of compressor that operates in cycles, typically between 0 and 100 percentage of time. This type of compressor is best suited for applications where the compressed air needs to be available intermittently, such as in industrial or construction settings. Typically, the compressor cycle time is in the range of 2 to 30 seconds. For example, a typical compressor may operate at 90 percent duty cycle between 10 and 15 seconds and then return to 0 percent duty cycle for 5 seconds.
In many cases, an intermittent duty cycle will be sufficient to allow you to accomplish the work at hand without sacrificing productivity levels. Here are a few illustrations:
- Inflating a car tire
- Drilling holes
- Using a cutting disc
- For an air nailer or hammer
- Home DIY tasks
What is a continuous duty cycle compressor good for?
Continuous duty cycles allow you to provide consistent power to machines and tools while also reducing the likelihood of equipment failure and downtime. Examples of circumstances in which this may be advantageous include the following:
- Using a sander
- Manufacturing processes