How to tell a cartridge needs replacement?

Replace immediately if any of the following occur: 1) Media damaged, cracked or punctured with dust escaping the outlet; 2) Severe caking where resistance stays high after washing/multiple cleanings and suction drops sharply; 3) Cartridge deformed or pleats collapsed, seal failed; 4) Media aged/powdered, filtration accuracy lost; 5) Service life far exceeds standard with severely degraded performance.