Read the stack from dirty side to clean side

Every layer has one job. Confusing them is how buyers end up with a filter that blinds in a week, or one that costs 40 % more than the duty requires.

What the rating really means

Ask for absolute rating if downstream equipment is expensive. A 10 µm nominal laminate can pass particles well above 10 µm — acceptable for pre-filtration, unacceptable in front of a catalyst bed.

Cleaning: the real cost driver

• Backflush from clean side only — reverse flow through L2 lifts the cake intact instead of driving it deeper.
• Pressure ramp, not shock — sudden pulses deform the control layer and quietly widen the rating.
• Dry or solvent flush after caustic — residue crystallises inside the tortuous path and becomes impossible to remove.
• Track Δp after each clean — a rising baseline means irreversible plugging, not a cleaning problem.

Specification checklist

Where the five-layer laminate is the wrong choice

If the duty is coarse pre-filtration above 200 µm, a single woven mesh does the same job at a fraction of the cost. If the medium is highly viscous or heavily loaded with fibrous material, a pleated cartridge gives more surface area and longer intervals. We will say so before quoting.