1. What Is DOP/PAO Leak Testing for HEPA Filters?

1. DOP Leak Testing

DOP (Dioctyl Phthalate) is a traditional testing method for high-efficiency filters.

During the test, an aerosol generator produces test particles upstream of the filter, and a photometer scans the downstream side of the filter.

Testing process:

Aerosol Generator

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DOP Aerosol

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HEPA Filter

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Photometer Scanner

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Leak Detection

It is mainly used to detect:

• Damage to the filter media;

• Incomplete sealant;

• Leakage at frame connections.

2. PAO Leak Testing

PAO (Poly Alpha Olefin) is currently a more widely used integrity testing method in the cleanroom industry.

Its principle is similar to DOP testing. PAO aerosol is introduced to detect whether the filter has any localized leakage.

The test mainly checks:

• Filter Media Integrity

• Frame Sealing

• Gasket/Gel Seal Performance

PAO testing is widely used in:

• GMP pharmaceutical plants;

• Hospital cleanrooms;

• Biological laboratories;

• Semiconductor production environments.

2. What Problems Does DOP/PAO Leak Testing Detect?

1. Filter Media Integrity

The test determines whether the HEPA filter media has:

• Minor damage;

• Broken fibers;

• Manufacturing defects.

2. Frame Sealing Performance

In actual engineering projects, many leaks occur at the structural connection points of the filter, such as:

Filter Media → Sealant → Frame

Insufficient sealant or weak connections may cause bypass leakage.

3. Reliability of the Sealing Method

Common HEPA sealing methods include:

Gasket Seal

Characteristics:

• Lower cost;

• Convenient replacement;

• Higher requirements for installation accuracy.

Suitable for:

• General clean environments;

• AHU systems.

Gel Seal

Characteristics:

• More stable sealing performance;

• Can compensate for installation deviations;

• Lower leakage risk.

Suitable for:

• Pharmaceutical facilities;

• Medical facilities;

• High-grade cleanrooms.

3. What Test Reports Are Required When Purchasing HEPA Filters?

1. HEPA Efficiency Test Report

This report confirms the filtration class and performance parameters.

It mainly includes:

2. DOP/PAO Leak Test Report

This is a key document for verifying filter integrity.

The report should include:

• Test method;

• Test aerosol;

• Leakage rate;

• Product serial number;

• Test date.

For pharmaceutical, hospital, and laboratory projects, buyers are advised to require an individual test record for each filter.

3. Material and Quality Certificates

The following materials should be confirmed:

Filter Media

• Glass Fiber

• PTFE Membrane

Frame

• Aluminum

• Galvanized Steel

• Stainless Steel

Seal

• PU Foam

• EPDM

• Gel Seal

4. How Should HEPA Filters Be Selected?

Different applications have different priorities:

Pharmaceutical Cleanrooms

Key requirements:

• H14 class;

• PAO leak testing;

• Gel Seal structure;

• Complete test reports.

Hospital Operating Rooms

Key requirements:

• Stable filtration efficiency;

• Low pressure drop;

• High sealing reliability.

Semiconductor Industry

Key requirements:

• High efficiency;

• Low particle shedding;

• PTFE filter media.

HVAC Systems

Key requirements:

• Airflow matching;

• Initial pressure drop;

• Service life.

5. Procurement Advice: How Can You Evaluate a Reliable HEPA Supplier?

Do not compare price alone. Buyers should confirm:

✓ Whether efficiency test reports are provided
✓ Whether DOP/PAO leak test reports are provided
✓ Whether complete testing equipment is available
✓ Whether product batch traceability is supported
✓ Whether the supplier has cleanroom engineering experience

6. Yueboyang HEPA Filter Quality-Control Solution

Jiangsu Yueboyang Purification Equipment provides HEPA filtration solutions for cleanrooms, medical facilities, industrial HVAC systems, and other applications.

Production process:

Raw Material Inspection

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Filter Assembly

↓

Efficiency Test

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PAO Leak Test

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Final Inspection

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Product Delivery

Through strict testing procedures, Yueboyang ensures that its HEPA filters meet customer requirements for filtration efficiency, sealing performance, and long-term operational stability.