ISO 4548-2:1997 PDF

Overview

ISO 4548-2:1997 specifies standardized test methods for the element by‑pass valve characteristics of full‑flow lubricating oil filters used on internal combustion engines. It defines how to set up a test rig, prepare the filter (including use of a non‑permeable dummy element or separate housing for spin‑on types), select test liquids, and measure differential pressure, leakage and valve opening/closing behaviour across a range of flow rates. The purpose is to ensure the by‑pass valve maintains oil supply under choke or cold‑start conditions while minimising unfiltered oil flow during normal operation.