Don’t Skip the Keel Support Frame for Pleated Pre-panel Filters!

Many people think, “A pleated pre-panel filter is just filter media plus an outer frame— the keel support frame doesn’t matter”.

 But in practice, filters without a keel collapse after just two months of use. Unfiltered dust gets sucked into fans, causing frequent shutdowns for cleaning, 

and annual filter replacement costs are nearly 50% higher than those with keel frames.

Though the keel support frame seems like a minor component, it is the key to ensuring the filter’s performance and cost-effectiveness. 

It serves three indispensable functions:

1.Support the filter media against collapse and maintain 100% filtration area

The non-woven filter media of pre-panel filters is inherently soft and elastic. Without the support of a keel frame, two major issues occur in ventilation systems:

First, the middle of the filter media collapses, crumpling the originally flat surface and reducing the filtration area from 1 m² to just 0.6 m²—failing to capture dust and lint in workshops effectively.

Second, uneven fitting leads to edge warping and excessive tension in the center, rendering parts of the media ineffective. 

In tests, filters with keels capture 50% of particles larger than 5 μm, while those without only capture 30%. In office building fresh air systems, filters without keels even cause fine dust to blow out of air conditioning vents.

2.Prevent air leakage, protect downstream equipment and reduce clogging issues

Pleated pre-panel filters act as the first line of defense in ventilation systems. Air leakage allows unfiltered dust to directly enter downstream fans and heat exchangers, causing frequent equipment breakdowns. 

The keel frame solves this problem by pressing the filter media tightly and securing it to the frame, eliminating air leakage.

More importantly, it prevents media displacement. The airflow impact during system operation can easily shift media without a keel, even blocking air ducts by sticking to outlets. 

With a keel frame, the media stays firmly in place regardless of airflow intensity, ensuring stable ventilation and avoiding reduced airflow over time.

3.Extend filter service life and save two months’ worth of consumable costs annually

The replacement frequency of pre-panel filters is directly linked to the media’s dust-holding capacity. When media collapses without a keel, dust only accumulates on the surface, requiring replacement in one month.

 With a keel frame, the media remains flat and stretched, allowing dust to be evenly absorbed into the deep layers—boosting dust-holding capacity by 50%.