Air Flow VS. Static Pressure Fans – Choosing Between the Two

Buying the right fans can make a world of a difference in your air cooling, or water cooling PC setup. Fans are all optimized for different purposes and knowing what the fans are optimized for can help you in the long run.

Computer fans generally come in two specific optimizations which are air flow, or static pressure. Most fan manufactures will have two series of fans that they produce with these two optimizations in mind. One series can be designed for high air flow and another series for high static pressure.

This is probably one of the many reasons why beginner PC builders get confused when buying new computer fans. It’s already confusing with fan specifications but to add in optimized fans into the mix can make it quite complicated.

So in order to help you guys out, I’ve made this short simple guide to help you understand the difference between air flow and static pressure fans. And guide you with your decision on what type of optimized fan you should use.

What is the differences between air flow and static pressure fans?

Understanding the two differences is quite simple. But in order to understand the difference you need to know what each one is optimized to do.

air flow fan vs static pressure fan different air flowsFans that are optimized for air flow means that the fans are able to move a certain amount of air (CFM), depending on the RPM, in an open-air setting. Open-air settings are where there is no resistance around the fan, front or back, that can obstruct the air flow. The fans are free to move the air through the open space.

Static pressure fans are fans that are optimized with resistance in mind. So they are designed and measured (mm/H2O) by how much resistance the fans can push/pull the air through. This means that the fans are specifically designed to push through resistances that are in the way of the fans. A good example would be a static pressure fan on a radiator of a water cooling setup. Static pressured fans will be able to push and move the hot air through the tiny fins of the radiator better than an air flow fan.

Now that you know what each one is optimized to do, lets get to the differences. Differences between air flow and static pressure fans are really in the fan blade design and how different the air flows between the two.

Difference in Fan Blade Designs

The major difference in air flow and static pressure fans are the blade designs. The blades of the fan can tell you what type of optimization the fans are designed for. And different fans have different blade designs which means that the cooling performance will be different as well.

Air Flow Optimized Blade Design

Air flow fans tend to have skinnier fan blades with much more open gap between each blades. Most air flow fans also have a lot more blades than the static pressure fans since the blades are skinnier. The main purpose behind this fan blades design is to allow as much air to flow through the fan as the blades rotates. The air will be able to travel straight through the fan with more ease.

air flow optimized fans

Static Pressure Optimized Blade Design

As for static pressure fans, the blades are wider and the gaps between each blade are smaller. There are also smaller gap between the blades and the outer chassis ring. This design doesn’t allow air to flow freely through the blades like the air flow fans, but instead the air has no choice but to go through the fan blades. The pressure of the air will be more focused on the outer ring and not in the center.

static pressure optimized fans

Hybrid Blade Designs

There are also hybrid blade designs where the blades are designed with both air flow and static pressure optimizations in mind. These fans allows you to have good air flow as well as high static pressure for the best cooling performance. The blade design will be similar to static pressure fans with wide blades but there could be more curve to the blades as well as more opening gap between the blades.

hybrid optimized fans

Air Travel Differences

Another difference between the two is how the air travels through the fan and what kind of air pattern is created. The blades will determine how the air travels through the fan and exits out of the fan. Different blade design will give different air flow patterns and since we can’t see air we have to rely on the Cubic Feet Per Minute (CFM) that is provided in the specifications of the fan. The CFM just shows us how much air the fan can move and so higher the CFM the better the fan is.

Note: Air travel is just an alternative word for air flow that I just made up. I just didn’t want to confuse you guys by saying air flow to mean air flowing and the air flow fans.

Air Flow Fans

air flow fan air patternFor air flow fans, the direction of the air travel will be more straight. What I mean by this is that the air will travel straight through the fan as far as the fans allows it to go in a ideal straight line. The air being pushed will be more focused in the center and gets wider as the air travels. That is why air flow fans are optimized for open-air settings where the air can travel without anything blocking it’s way.

Static Pressure Fans

static pressure fan air patternThe air travel for static pressure fans can vary between different blade designs, but generally the air will spreads outwards as it travels through the fan blades and the pressure will be more focused on the outer ring more than the center. This is why these fans are designed with resistance in mind so that the fan can push the air through small openings or spaces.

To make sense of how the air travels, you should take a look at the diagram that I’ve created to help make your understanding of these fans better.

So What Type Of Fan Do You Need?

The type of fan you need really depends on what areas you’re going to place your fans on. The ideal location for air flow fans will be open areas where the air can travel freely. Locations for static pressure fans are mostly in areas where there is restrictions that can block the air flow.

My recommendations on places you can place these types of fans:

  • Air Flow Fans – Open areas for intakes and outtakes. You can use air flow fans on front and bottom case intakes. Or you can use them as outtakes for back and top case outtakes. But remember to have them in open areas or they won’t perform as well. Keep in mind that cases that don’t have meshes or space in front of the fan can hinder the air flow of these fans as well.
  • Static Pressure Fans – These fans are best used in places where the air flow is obstructed such as radiators and CPU heatsinks. You can also use these fans as intake fans that have hard drive disk bays right next to the fan.

Air flow vs static pressure-fan proper mount placement

Fan placement can be a trial and error kind of deals. You probably won’t get it right the first time but as long as you remember where the two types of fans should go then you’ll be alright. Air flow fans are best used in non-obstructed areas while the static pressure fans are best in obstructed areas.

To Conclude

Air cooling is all about mixing different types of fans to make the best possible air flow for your PC. Air flow fans and static pressure fans should be used in combinations to help you move as much heat away from your PC as possible. And now that you know what the differences are you should be able to come up with the best air cooling setup for your PC.

If you have any questions, concerns, or need help, feel free to leave a comment below. Thanks. 🙂

Also check out my fan buying guide to help make your fan purchase as easy as possible.

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