// PRE FILTERS
There are typically 2 types of pre filter, panels and bags. Both serve the function of removing the larger particulate from the fume, increasing the life of the HEPA filter. They act as a sieve for particulate.
// PANEL FILTERS
Panel filters are traditionally considered in the industry as in effective for laser fume, why? Because the relative narrow depth means they have limited surface area and require changing more often. They also struggle to handle the required high airflow rates used in laser fume processes.
//BAG FILTERS
Bag filters are the preferred method due to their large surface area and the pleated design allows for larger volumetric containment. They also contribute to a filtration system known as reverse air flow. This is discussed later as a method of improving a filters life cycle and ensuring maximum air flow through a fume extraction system.
Some manufacturers have their own pre filter designs. BOFA have the deep pleated pre filter and Purex have developed the labyrinth pre filter. Both are essentially the same, they work on the reverse air flow principle and the differences are minimal. However Purex systems are considered better at containing contaminants when filters are being change as all particulate remains within the filter itself.
