Metrolab Blog

Particle Counters Knowledge Hub 12

𝙃𝙤𝙬 𝙩𝙤 𝙏𝙚𝙨𝙩 𝙄𝙣𝙨𝙩𝙖𝙡𝙡𝙚𝙙 𝙃𝙀𝙋𝘼 𝙁𝙞𝙡𝙩𝙚𝙧 𝙄𝙣𝙩𝙚𝙜𝙧𝙞𝙩𝙮❓

☑ Measure the aerosol concentration upstream of the filters

☑This aerosol concentration should be used as the upstream 100 % reference for the photometer. Downstream measurements are then displayed as percentage penetration of upstream concentration

☑The probe should then be traversed at a scan rate not exceeding 5 cm/s

☑Using overlapping strokes (1 cm recommended)

☑The probe should be held at a distance of 3 cm or less from the downstream filter face or the frame structure

☑Scanning should be performed over the entire downstream face of each filter, the perimeter of each filter, the seal between the filter frame and the grid structure, including its joints

☑ Measurements of the aerosol upstream of the filters should be repeated at reasonable time intervals between and after scanning for leaks, to confirm the stability of the challenge aerosol concentration (should not vary more than ±15 %)

Installed HEPA filter integrity testing steps as per ISO14644-3