Pore Size – Absolute Rating

An absolute rating expresses a guaranteed retention threshold tied to a defined pore size and a validated test method, rather than a nominal or average value. In practice, an absolute pore-size rating is established by challenge testing with calibrated particles or organisms under specified conditions and is often linked to a bubble‑point limit that evidences the largest through‑pore. Unlike nominal ratings—which can vary widely with test protocol—an absolute rating commits the supplier to a specific cut‑off with stated confidence, sometimes expressed as log‑reduction value (LRV) or beta ratio for hydraulic filters. For woven technical fabrics and sintered meshes, achieving an absolute rating requires tight aperture tolerances, stable geometry under operating tension and temperature, and clean, damage‑free seams and gaskets that prevent bypass. Users should always request the underlying method (test fluid, particle type, wet‑out procedure, temperature), acceptance criteria and allowable drift after defined cleaning cycles. In plant commissioning, correlating absolute rating to filtrate turbidity or particle‑count thresholds, and verifying bubble point and mean‑flow pore size, ensures that the laboratory definition translates into reliable B2B performance over long campaigns.