Everything You Need to Know About Compressors: Different Types, Sizes, and Capabilities

We offer a lot of compressors here at HornBlasters. In fact, we currently stock over 60 different models. With so many options to choose from, we get a ton of questions from customers wanting to know what compressor would be the best fit for their needs. Even when buying a Horn Kit, picking the horn is usually the easy part. The hardest choice is usually what compressor to run.

Not every compressor is made equal. We have some compressors that are small enough to fit on a motorcycle and we have some that are so large that we have to ship it out on a pallet. While some compressors outright perform better than others, every one of them have their own applications. Today we take a look at the different styles and size compressors we offer and how they are best utilized, arming you with the knowledge to ensure that your onboard air system will do everything you need it to.

The Right Tool for the Job

Before we go over all of the different kinds and sizes of compressors that we carry, it’s good to first get an idea of what separates them from each other. Most people know that the bigger the compressor is, the more powerful that is, but there are certain metrics to look out for when choosing a compressor.

HornBlasters 2 Gallon 6 Port Air Tank
HornBlasters 5 Gallon 8 Port Air Tank
HornBlasters 8 Gallon 8 Port Air Tank

Tank Size

First, you want to take in to account how big of an air tank you will be filling up. Some compressors will only fill up to 1 gallon and some will fill up to 5 gallons of air with many compressors falling somewhere in between. You don't want to try to run a compressor that is not built to handle a bigger tank, because that will cause it to work a lot harder than it was designed, and can cause issues to the internals. But you also don’t want to waste money on an overpowered compressor to fill a single gallon tank. Knowing exactly what compressor is best for your size tank and application can save you time and money.

Pressure Rating

You also want to know what pressure your compressor is rated for. Some compressors can easily push 200 PSI, others are made to only handle up to 120 PSI. Knowing what you will be using your onboard air for and what the best pressure to run to accomplish that are important. For example, most of our air horns and train horns run best at 150 PSI. If you get a compressor that can only do 120 PSI, you won't be able to get the full volume that you could out of your horns.

Speed vs. Endurance 

Many of the compressors that we carry are designed to be either Fast-Fill or Constant Duty. Fast-Fill compressors are designed to do exactly what it sounds like, fill up your air tank as fast as possible. Constant Duty compressors are designed to run continuously for as long as possible. Some of the top of the line air compressors we offer can be considered both a Fast-Fill and a Constant Duty Compressor. We will get into the benefits and applications of each type further down, but knowing what kind of compressor you have will give you an indication of what it is capable of and definitely important to consider before making a purchase. 

ONE HOUR DUTY CYCLE ( 100 PSI @ 72°F ) MINUTES ON / MINUTES OFF

9% Duty Cycle

5 Min. On / 55 Min. Off

10% Duty Cycle

6 Min. On / 54 Min. Off

15% Duty Cycle

9 Min. On / 51 Min. Off

20% Duty Cycle

12 Min. On / 48 Min. Off

25% Duty Cycle

15 Min. On / 45 Min. Off

30% Duty Cycle

18 Min. On / 42 Min. Off

33% Duty Cycle

20 Min. On / 40 Min. Off

50% Duty Cycle

30 Min. On / 30 Min. Off

100% Duty Cycle

1 Hour Run Time

Duty Cycle

A compressor’s duty cycle is a measurement of how long the compressor can continuously run within a given time period at a certain pressure. For the compressors that we carry, that given time period is 1 hour. You will usually see them rated at either 100 PSI or 200 PSI. So for example, a compressor rated at a 25% duty cycle at 100 PSI will be able to run for 15 minutes of that hour and need to rest for 45 minutes. That means that a compressor that has a 100% duty cycle can run for a full hour continuously without having to stop if you are running it at 100 PSI. If you are running 150 PSI, like many of our train horn kits do, that would give you a 50% duty cycle, so you would want to take that into account.  

PSI CFM A
0 2.62 16
10 2.39 18
20 2.21 20
30 2.11 22
40 2.01 24
50 1.93 25
60 1.84 26
70 1.73 27
80 1.65 27
90 1.52 27
100 1.45 27
110 1.35 27
120 1.26 27
130 1.19 27
140 1.08 27
150 1.01 26

CFM

CFM, or Cubic Feet per Minute, is the measurement of airflow out of the compressor. Basically, the higher the CFM, the higher-performing the compressor is. CFM is typically measured at zero point air pressure, also known as free flow. While this is a good indication of the power of a compressor since the measurement is taken at zero pressure and our kits are always pressurized, so the number can be a little misleading. Just use it as a general rule of thumb to compare the power between compressors, but don’t worry too much about the actual number. The compressor’s fill rate will give you a better idea of what it can do under pressure.

IP Number Object Size Protected Against Effective Against

IP54

Protected from limited dust ingress.

Protected from water spray from any direction.

IP67

Protected from total dust ingress.

Protected from immersion between 15 centimeters and 1 meter in depth.

IP Rating

Some compressors are built to withstand the elements and some are designed to be kept away from the elements. The best thing you could ever do for your compressor is to know what your compressor is made for and install accordingly. Installing a compressor in an area where it can get wet when it isn't designed to be is a sure-fire way to damage your compressor and void your warranty, so be sure to install your compressor where the instructions tell you to!

Thankfully there is a standardized rating system that tells you how protected your compressor is from the elements. This rating is called an IP Rating, also known as an Ingress Protection rating. Most of the compressors we carry either have an IP rating of IP54 or IP67. Compressors with an IP rating of IP54 have limited protection against dust and are protected against splashes of water. These would be our non-enclosed compressors typically seen on our Air Source Units such as our 127H and 228H kits. Compressors with an IP rating of 67 are fully protected from dust and protected from short immersions in water. Those would be any Viair Compressors 325C and up as well as our other brand compressors like the Air Zenith OB2 and the Oasis XD4000 compressors.

Portable Compressors

While not designed for any of our horn kits or onboard air systems, the portable compressors that we offer deserve an honorable mention as they can definitely help get you out of a tight spot. If you decide to forgo a full-fledged onboard air system and have something that isn’t stuck on a single vehicle, our portable compressors are a perfect fit for you. Mainly used for tire inflation, each compressor will have different size tires that they are able to fill. Make sure to check our product page for each system to ensure that it can handle the size tires that you have.   

Viair 92C Air Compressor

Light Duty

Next up, you have our Light Duty Compressors. These little devils are designed for the smallest onboard applications, most commonly supporting air suspension or air lockers for motorcycles. While not as common, you can power our air horns and train horns with them as well, as the higher performing light-duty compressors can fill up to a one-gallon tank and support up to 120 PSI of pressure.

While powering air horns and suspension may not come as a surprise to anyone, many of the Viair light-duty compressors that we carry have also been used to power robots. You read that right. Robots. Used in the First Robotics Competition, where high school students design and build robots to compete against each other in-field challenges, Viair’s light-duty compressors are favored by many students due to their exceptional power for their size.

Viair 275C Air Compressor

Medium Duty

Slightly larger and quite a bit more powerful than light-duty compressors, medium-duty compressors can fill larger tanks and run at a higher PSI than their light-duty counterparts. While medium-duty compressors are still mostly used on smaller vehicles such as motorcycles, their ability to run up to 150 PSI of pressure and support a tank up to 2.5 gallons in size means that that can be used on larger vehicles like cars and trucks.

If you are tight on the room to install or have a tight budget to work with, these are great compressors that will get the job done. While they may not be powerful enough for applications such as air tools or tire inflation due to their lower duty cycle compared to heavy-duty or constant duty compressors, they can be great for things like air lockers, Jake brakes and air horns.

Our most popular medium-duty compressors would be the Viair 275C and the Viair 280C that are direct replacements for out 127H and 228H air-source units, respectively.  

Viair 400C Chrome Air Compressor

Fast Fill

Now we start getting into the higher-performing compressors. Fast-Fill compressors are designed to do one thing really well: Fill up your air tank as fast as possible. While these are certainly the fastest out of all the compressors, they do sacrifice duty cycle in order to achieve that speed. Most fast-fill compressors don’t have a duty cycle above 33%, meaning that they can only fill for about a third of every hour before they need to cool off. So, for every 20 minutes that they run, they need to cool for about 40.

While they won’t be running any marathons, fast-fill compressors will definitely win a sprint, with the fastest compressors we carry able to recharge a 5-gallon tank on about a minute and a half and recharge a 2-gallon tank in under a minute. These types of compressors are usually best for people that only want to use their air system for their air horn or train horn. The fast refill means you will always have air for your horn when you need it, but most people don't drive around laying on their horn, so the short duty cycle isn’t really a problem.

Our most popular fast-fill compressor would be the Viair 400C that powers our 240 and 540 horn kits and onboard air kits.

Viair 444C Stealth Black Air Compressor

Constant Duty

Our workhorse compressors. Constant duty compressors are designed to run for as long as possible before they need to shut down to cool off. All constant duty compressors have a 100% duty cycle, but make sure to note at what PSI they are rated at. Some of our more common constant duty compressors, like the Viair 380 or the Viair 444C, have at 100% duty cycle at 100 PSI. Since our kits usually run at 150 PSI, they are not truly constant duty, with a duty cycle at 150 PSI at 75%. This means that they can run for about 45 minutes straight, but does need to cool for about 15 minutes before they need to cool. Still, they are great compressors for handling most pneumatic tasks you would come across, such as tire inflation, ait tools and air suspension.

Our most popular constant duty compressors would be the Viair 444C that is featured in our most popular horn kits and onboard air systems such as the Conductor's Special 444K Nightmare Edition Train Horn Kit.

Top of the Line

The following compressors are the best of the best. While they are all classified as constant duty compressors as well, their exceptional performance puts them in a class of their own. If you have some serious pneumatic jobs to tackle or if you just simply demand only the best for your ride, these compressors get the job done quickly and in style.

Viair 485C

The latest and greatest compressor from Viair. This beastly compressor from Viair combines all the things you love about previous Viair compressors and gives it to us and a sleek compressor with a new head design. With a 100% duty cycle at 200 PSI, the Viair 485C is one of the few compressors that have the power to run our 150 PSI horn kits and onboard air systems truly constantly. Also, you are also getting a fill time close to their fast-fill compressor speeds, with the Viair 485C able to recharge a 2-gallon tank from 110-145 PSI in just under a minute. On top of that, the 485C runs even quieter than any compressor before with the new head design. The Viair 485C Air Compressor can be found in our 2485 and 5485 horn kits and onboard air systems.

Air-Zenith OB2

While not included in any of our premade kits, if you are looking the build a ridiculously powerful custom system, running even a single OB2 will double the speed you would get from your average compressor. With a 100% duty cycle at 200 PSI, the Air Zenith OB2 has absolutely no problem taking on any pneumatic task you can throw at it. With just a single OB2, you can recharge a 5-gallon tank from 110-145 in just over a minute and if you are running dual OB2’s, you can recharge a 5-gallon tank from 110-145 in just 35 seconds!

With the Air Zenith OB2’s extreme and polished and sleek look, they are a common staple on many high-end systems. Twice the power comes with a price, however. The Air Zenith OB2 pulls about twice as many amps from your battery than other compressors in its class, so keep that in mind, especially if you plan on running two.

Inside Accuair Endo CVT & CT

Accuair ENDO CT and CVT

While not just a compressor, you can’t talk about our most powerful compressors without mentioning the Accuair ENDO system. The Endo CT and CVT are the first fully self-contained onboard air systems, with the compressor actually mounted inside the air tank! The compressor itself is a powerful Wabco compressor made specifically for the ENDO system. The Accuair ENDO system is 100% constant duty up to 200 PSI, so they are more than capable of handling pneumatic tasks, such as air inflation, air tools and suspension. If fact, the ENDO system is perfect with air suspension, especially the CVT version that comes with either a built-in 2-corner or 4-corner valve to control your bags. Even if you don’t plan on using it for bags, the Accuair Endo system is just a great all-around system that, thanks to its internal compressor design will give you the cleanest and most polished build you can get in an onboard air system. Thanks to their unique design, the Accuair ENDO systems run the quietest as well.    

Oasis XD3000 and XD4000 

The Oasis XD3000 and XD4000 Air Compressors are military-grade industrial compressors and are by far the most powerful compressors that we carry. These aren't compressors for your everyday build. The Oasis compressors that we carry are used by the military and government, service trucks, storm chasers, and tow trucks. If there is a situation where you need some heavy-duty air to run power tools or anything else, these are the compressors that you want on your truck. Both compressors are truly constant duty compressors with a 100% duty cycle and have an insane output, with the XD3000 with a CFM of 14 and the XD4000 at a CFM of 15. Simply put, these compressors are almost 10 times as powerful as most of the other compressors we carry. In fact, you can power a 1/2" impact wrench straight from the compressor without even needing an air tank!

A Compressor for Every Occasion

While having so many compressors to choose from it can seem intimidating at first, once you get to know the basics, it’s easy to choose the right compressor for your needs. Some people just want to blast their horns occasionally, some want to make the most out of their onboard air system. Whatever you need, you can be assured that we will have the right compressor for you.