Fan balancing quality

This article is about the balancing quality of fans.

Introduction

Today, many technicians are still guided by the ISO 1940 regarding the balancing quality of fans although this standard has been discontinued in 2016 and replaced by ISO 21940-11.

On the other hand, at ISO 10816-3 recommends using the ISO 14694:2003 for the evaluation of fan vibrations and balancing.

This standard goes further than the ISO 21940-11 because it takes into account the fan application for the definition of balancing tolerances.

When it takes place vibration analysis in fans, in a vibration analyzer when performing predictive maintenance, common vibration analyzer This article presents the vibration limits in rotary-dynamic pumps as defined in the ISO series of standards..

Fan balancing quality – ISO fan rating 14694

In another article, the topic of Vibration Limits in Fans according to this standard.

In fact, it states that the design/structure of a fan and its intended application are important criteria for categorizing the various types of fans in terms of degrees of balance and applicable vibration levels..

It shows the following table, regarding its classification according to its application:

Required balance degree according to application category

For the different application categories, the required degree of balance is shown in the table below..

Balance quality grades

Fan application category	Balance quality grade for rigid rotors
BV-1	G16
BV-2	G16
BV-3	G6,3
BV-4	G2,5
BV-5	G1,0

It can be seen that the degree of balancing quality of fans, varies between G1 and G16.

Fan balancing quality – Conclusion

Especially for fans that fall into categories BV-4 and BV-5 the ISO requirements 21940-11 are inappropriate.