Leak is local, but Efficiency is global.
Efficiency is the measure of the entire filter and is the average of variations in the performance of the filter media.
Local leak test is the measurement under a probe (scan head) that scans for the possible defects-leaks, not local variations.
These tests are manufacturer’s tests carried out acc. to standard EN1822 on individual, not installed filters at place of manufacture. Test reports are usually part of filter package.
When a filter is installed in the clean room or equipment, user should perform the installed filter leakage test. The test is a leak test of the complete filter installation comprising the filter media, frame, gasket and grid system. Refer to standard ISO14644.