Commercial air-conditioning and ventilation systems usually use staged filtration: a pre-filter stage protects downstream equipment, while a medium-efficiency stage carries most of the particle load. Panel pre-filters are simple and easy to maintain, making them a practical first stage.
Pocket bag filters provide more media area and dust capacity within the same installation space, suiting air handlers with higher airflow and longer maintenance intervals. Selection should consider initial resistance, final resistance, pocket count and pocket length.
Set filter grade and replacement intervals from site air quality, air-change rate and maintenance plans, and use differential-pressure monitoring to decide when replacement is actually needed.