Airflow vs Noise


Determine the airflow needed to provide adequate cooling. There are many ways to scientifically calculate this. In real world applications these methods aren't always accurate. A common method is to calculate the cubic footage of the area to be cooled and multiply by 3. This will give you a number relative to CFM ratings that will replace the air in that space 3 times per minute. Fan airflow is measured in CFM (Cubic Feet per Minute)
In a real world application there will be components in that space that are generating heat. This considered you might need to replace the air 4, 5 maybe 6 times per minute. To simplify we break it down into three category levels...

1. Circulation: No heat problems, but some heat is felt and the goal is to get some air movement in the cabinet.
2. Airflow: Increasing heat making the cabinet noticably hot. Not too hot to touch but in the 90 degree F range.
3. Cooling: High heat levels causing thermal overload on components. 100+ degree range.

For Circulation, less powerful fans and fewer fans can provide adequate circulation. This is ideal for noise sensetive environments.
For Airflow, medium powered fans and deploying more fans will provide the airflow needed to properly cool the area.
For Cooling, higher power fans and the use of multiple fan systems are often required to obtain proper cooling.

All Procool systems have CFM ratings to help determine the best system based on airflow.
Another rating to look at is the static pressure rating. This is basically the power of the airflow. Like CFM ratings this will indicate more or less pressure.
Higher pressure fans are preferred in larger cabinets where the air has farther to move.


Fan noise is calculated in decibels dBA. Like airflow, higher ratings equal more noise as lower ratings equal less.
Procool pioneered quiet cooling systems that provide the same airflow as other more noisy systems.
All procool cabinet systems employ this technology to provide adequate airflow without noise.
Procool rackmount fan systems range in noise levels depending on the airflow.

Fan noise is reletave to the airflow. This is because to provide more airflow the fan blade must spin faster. The faster it spins, the more noise will be generated.
Procool SX and SXT series fans are specially designed to push more air with less noise. The other Procool fan models such as TV and T series are higher power fans with higher noise levels.

A typical breakdown of noise levels:

0 dBA - Silence (hearing threshold)
10 dBA - a pin dropping
20 dBA - Mosquito
30 dBA - whisper
40 dBA - computer
50 dBA - A normal room
60 dBA - Normal Conversation
70 dBA - Laughter
75 dBA - vacuum cleaner
80 dBA - alarm clock
90 dBA - lawn mower