HVAC Qualification

HEPA Filter Integrity (Leak) Test Calculator

Calculate percent penetration from aerosol photometer scan readings and check each scan point against the standard leak acceptance criterion.

How the Integrity Test Works

HEPA filter integrity (leak) testing challenges the installed filter with a known upstream aerosol concentration (commonly PAO or DOP), then scans the downstream face of the filter, frame seal, and housing with a photometer at a defined speed and overlap to detect any local leak path.

% Penetration = (Downstream Concentration / Upstream Concentration) × 100

Standard Acceptance Criterion

Parameter	Typical Requirement (per ISO 14644-3 / IEST-RP-CC034)
Local (scan) leak penetration	≤ 0.01% at any single scan point
Scan probe speed	Typically ≤ 5 cm/second
Scan overlap	Typically ~50% of probe width between passes
Overall filter efficiency	Typically ≥ 99.99% (HEPA) or ≥ 99.999% (ULPA), per filter class

Interactive Calculator

Upstream Aerosol Concentration

In photometer units (e.g., % or µg/L, consistent with downstream)

Acceptance Threshold (% Penetration)

Scan Location	Downstream Reading	% Penetration

Highest % Penetration

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Scan Points Failing

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This tool applies the standard percent penetration formula for educational and preliminary review purposes. Confirm your site's approved test method, photometer calibration status, scan speed/overlap, and acceptance criteria (which may vary by facility or filter class) before using results for filter release or qualification decisions.