Generally, there are two reasons to measure a centrifugal fan – the user wants to retrofit the fan (or parts) or replace it with a new fan. In either case, accurate measurements are critical to replicating the system currently in place, especially if no drawing is available. If possible, separate or isolate the fan from the system to access key measurement points. If duct work on the inlet or outlet is in the way, this could impact measurement accuracy.
The most basic answer to the question, “What does a centrifugal fan do?”, is that it moves gas (air), drawing it into the inlet, turning it 90 degrees, and blowing it through the outlet to exit the fan. It moves a higher static pressure than an axial fan, which moves air and gas straight, in one direction. Without air movement inside buildings – whether a room (like in Chet’s example in the video), a house, or an industrial manufacturing facility – things would get dicey. If you were to be trapped in a small room with no ventilation, only breathing in your own exhaled air, you could only survive for so long. Imagine what would happen in a manufacturing facility where there are many other gases and particles at play! If that is all the information on centrifugal fans you were looking for, feel free to stop reading now. For a little more on how they work, carry on.
A variable-speed fan is just what it sounds like. In this case, we’re talking about an industrial centrifugal fan that is capable of operating at more than one speed. That means it can run above or below the constant motor speed specified. There are several reasons why you would need a variable-speed fan, several ways to do it, and a few things to be careful to avoid when operating at varied speeds.
If you want to reduce a fan’s air volume and horsepower without adjusting speed, then you can use a damper to add system resistance. The damper can be installed on either the inlet or outlet side of the fan, and you can determine the best location based on your specific application and your fan performance curve. More often than not, we’ll recommend placing the damper at the outlet as the most cost-effective way to simply add resistance.
Troubleshooting and addressing fan performance issues can feel overwhelming, but with the five steps outlined below and the help of a trusted application engineer either remotely or on-site, you can find the solutions you need for your operations.
Sometimes the most simple things like cleaning get overlooked, potentially leading to many more serious issues. It’s important to properly clean a blower wheel, as material buildup on a wheel can cause vibration and damage your fan. Even “clean air” may contain various particles and debris. A simple cleaning procedure can keep your fan healthy and decrease downtime.
There’s more to a centrifugal fan than blade structure (versus axial) and function (to move process air and other materials as part of a larger system). Centrifugal fan airflow is at the core of how it works.
Fan static efficiency is the measure of the airstream’s potential, or optimal energy consumption, as determined by the ratio of power output to the power supplied.
If you work with a manufacturer that builds high-quality products, do a great job with the installation, and prioritize regular fan and blower maintenance, your industrial fan could last as long as 50 years. So what does all that mean? We break it down below and in Chet’s latest video.
Before we dive into HOW to balance an industrial fan, we should start with WHY. The answer is that the better we balance the wheel in a two-plane balance setup in the shop, the better it’s going to be when we put it into the complete fan assembly, run it up to full speed and trim balance it. And of course, ultimately, fan balance is essential to fan performance, safety, and maintenance.
