What Size Air Compressor For Blowing Out Sprinklers?

Sprinkler systems are crucial investments that need proper care all year round, and when winter approaches, you must perform one piece of essential winterization maintenance on your system – blow it out. It is the best way to ensure that the sprinkler system is dry during winter and free from damage due to water in the system freezing. The perfect tool for this job is the air compressor. If you are wondering what size air compressor you will need for blowing out sprinklers, we’ve got you covered!

Below we have gone through all of the size elements of the air compressor that matter the most for this particular job – which is important because air compressors are available in all manner of specifications, capabilities, and sizes. Our article will help you select the ideal air compressor rental or purchase for blowing out sprinklers.

Selecting the Right Size Air Compressor for Blowing Out Sprinklers

There are five factors you need to consider when choosing the right size air compressor for sprinkler blowout. They include the pressure within the air tank, airflow the system is capable of producing, and hose length.

If you’re not sure how to use actually use an air compressor to blow out your sprinkler system, I found this great video guide which explains it brilliantly. Credit to Works IRL.

PSI Needed

The range for recommended compressor PSI when it comes to blowing out sprinklers is from 50 to 80PSI. Of course, this figure depends on the type of pipes in your system. Just to recap, PSI stands for pound-force per square inch (PSI). It is the measurement for stress or pressure in the air tank. If an air compressor has high PSI or pressure, it means that it can extrude high force. It is important to balance the pressure so that it is too little that some water is left in the system or too high that it damages the system.

CFM Needed

CFM stands for Cubic Foot per Minute. For the blowing out operation to go according to plan, you need to have at least 20cfm from your air compressor. Some irrigation professionals who will even recommend as much as 50cfm. You will immediately know whether your compressor meets this threshold because the manufacturer will have indicated the rating on the compressor.

An important point to remember is that the larger the line, the higher the amount of air flow that will be needed to blow out the system. A large line typically is about 1 inch in diameter. A ½ inch line is categorized as small and will demand less airflow. Another thing to remember that anything below 20cfm may not blow out the water completely.

Air Tank Size Needed

Every compressor needs some time to fill its air tank, and it may run out before you complete blowing out the sprinklers. Experts in this area suggest using a tank of about 10 gallons capacity. Probably you have a compressor already but are unsure whether it is safe or adequate for the system. You could test it in several ways. Here is one: Run the unit for about two minutes continuously at not less than 20cfm – two minutes is the common time for blowing out a regular sprinkler system. If the pressure remains largely stable, your compressor is good for the job. If the pressure drops, you may need to buy a more powerful compressor or rent one.

Duty Cycle

As used in air compressors, duty cycle shows the time the air compressor spends running compared to time spent resting. Quick air compressor recovery times mean you can work with less breaks. Assuming that a compressor has a cycle time of 1 hour and a duty cycle of 30%, it means that it runs for 20 minutes, then goes into air compressor recovery time of 40 minutes more or less.

If you have an air compressor and can’t find the duty cycle anywhere, try just googling the make and model of your compressor. Write “duty cycle” after the make and model name and you should find it. You will most likely find the duty cycle details listed on websites for all current compressor types.

Note that the duty cycle ratings are generated under standard conditions of temperature and pressure. Often, higher or lower temperatures lower the duty cycle. Larger options such as durable, totally oil-free pancake compressor varieties are the best for blowing out sprinklers, but they are expensive. For more information on this, see our article Oil Vs Oil-Free Air Compressor.

Cord & Hose Length Needed

It is always important to choose the right power extension cord and air hose  to make your quality air compressor even better. Since this is an outdoor situation, we would recommend a 16-gauge power cord for the air compressor. Most air hoses are either 50 feet or 100 feet long, but there could be other lengths in between because the applications of body shop air compressors vary. If you wish to maximize the length, pick the 100-feet option. However, remember that there will some level of pressure drop for every increase in length. About 3.35 PSI is lost in 100cfm@90PSI traveling in a 1 inch 100 foot air hose.

In conclusion

It is not a secret how challenging getting rid of the last drops of water from the irrigation coverage of your sprinkler system can be. The process is not only tedious, but also dangerous in some instances. One thing for sure is that many products will be featured online with “amazing” capabilities. The impression they create is often much better than their actual performance.

As you consider which air compressor to use for your sprinklers, think about tank capacity, airflow rate, pressure and quiet air compressor and such factors. The best air compressor for blowing out sprinklers will have a balance of all these factors. It will neither leave water in the line nor blow out the sprinkler components.

If you have any doubt about the right size air compressor for this job, or even the process of blowing out your sprinklers, don’t hesitate to contact an expert or the manufacturer, or even ask us in the comments below.

For information on the right size air compressor for all manner of jobs, see our full guide with 41 real world examples – What Size Air Compressor Do I Need? You may also be interested in the other guides in this series:

Jeff Stelling

Jeff Stelling is an air compressor obsessive who has been working with compressors for over 25 years, since he was an apprentice engineer in the mid 90’s. He designed Aircompressorcompare.com to offer technical guidance and buying advice for compressors.

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