CFM is not selected from paper grade alone
Air permeability is one specification within a forming-fabric design. A universal CFM table by paper grade can be misleading because the value depends on the construction, measurement unit, test pressure and the machine's drainage system.
Confirm the measurement basis
Record the unit, test pressure, instrument and whether the value belongs to a specific model or an installed fabric. Do not compare values from different standards as if they were equivalent.
Define the machine requirement
Provide paper grade, basis weight, furnish and filler trend, retention program, width, speed, forming configuration, vacuum elements, current drainage and sheet-quality limits. Permeability must be balanced with fiber support, retention, formation, marking, stability and wear.
Use the current fabric as a baseline
Record the current construction, new-fabric specification, operating age, measured drainage, vacuum demand, drive load and failure mode. If a new permeability is tested, keep other main variables controlled and compare equivalent production periods.
PAPTEX parameter sheets contain model-specific values, not one universal recommendation for every tissue, packaging, kraft or board machine.
