2026-04-24
A Fan Filter Unit (FFU) is only as good as the HEPA filter inside it. The filter determines the cleanroom class, energy consumption, and replacement frequency. Choosing the wrong HEPA filter can lead to:
Failed certification (ISO 14644)
Higher energy bills
Frequent filter changes
Contamination risks
This guide walks you through exactly how to select the right HEPA filter for your FFU – whether you are a cleanroom contractor, lab manager, or overseas distributor.
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HEPA filters are rated by their efficiency at capturing 0.3 micron particles. For FFUs, two grades are common:
|
Grade |
Efficiency (0.3μm) |
Typical Cleanroom Class |
Application |
|
H13 |
99.95% |
ISO 5 – ISO 8 |
General manufacturing, labs |
|
H14 |
99.995% |
ISO 5 (critical) |
Pharma, hospitals, microelectronics |
|
U15 |
99.9995% |
ISO 4 or cleaner |
Semiconductor (rare for standard FFU) |
Recommendation:
For most FFU applications → H13 (best balance of cost and performance)
For strict GMP or sterile areas → H14
Avoid U15 – unnecessary for standard cleanrooms, increases fan load
�� Related: HEPA vs ULPA – Key Differences
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FFUs come in standard sizes, but not all HEPA filters are interchangeable.
|
Width x Height |
Depth |
Typical Use |
|
610 x 610 mm (2‘ x 2’) |
70 / 90 mm |
Standard ceiling grid |
|
1220 x 610 mm (4‘ x 2’) |
70 / 90 mm |
Larger FFU modules |
|
1170 x 570 mm |
70 mm |
European standard |
Check these before buying:
Actual dimensions (some brands use metric vs imperial)
Gasket type and location
Frame material compatibility
Always request a filter drawing from your FFU supplier before ordering replacements.
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The filter frame must fit the FFU housing and withstand the operating environment.
|
Frame Material |
Pros |
Cons |
Best For |
|
Galvanized steel |
Low cost, rigid |
Can rust in humid areas |
Dry manufacturing, labs |
|
Stainless steel 304 |
Corrosion resistant |
Higher cost |
Pharma, food, wet areas |
|
Aluminum |
Lightweight |
Less rigid |
Portable FFUs |
|
Plastic / ABS |
Cheap, disposable |
Short life |
Low-cost, single-use |
For most FFUs → Galvanized steel is fine.
For pharmaceutical or coastal environments → Stainless steel 304.
The seal between the HEPA filter and FFU housing prevents bypass leakage. Three common types:
|
Seal Type |
How It Works |
Leak Risk |
Typical Use |
|
Gel seal (liquid) |
Filter sits into gel-filled channel |
Very low |
Pharma, ISO 5 cleanrooms |
|
Knife edge |
Metal blade compresses gasket |
Low |
Standard cleanrooms |
|
Gasket (compression) |
Foam/rubber compressed |
Medium |
Non-critical FFUs |
Recommendation:
Gel seal – for critical areas where zero leak is required
Knife edge – best balance for most FFU applications
Gasket – acceptable for low-cost FFUs (ISO 7/8)
Pressure drop affects fan energy consumption and filter lifespan.
|
Filter Type |
Initial Pressure Drop (Pa) at rated airflow |
|
Mini-pleat H13 (70mm) |
120 – 180 Pa |
|
Mini-pleat H14 (70mm) |
180 – 250 Pa |
|
Deep-pleat H13 (150mm) |
80 – 120 Pa |
Rule of thumb:
Lower pressure drop = lower energy cost and quieter operation
But mini-pleat filters are more compact (better for shallow FFUs)
Most FFUs are designed for 70mm or 90mm deep HEPA filters. Check your FFU housing depth first.
For serious projects (especially export), your HEPA filter must come with documentation.
Required documents:
Individual efficiency test report (scan test or MPPS)
Leak test report (PAO / DOP)
Pressure drop measurement
Frame material certificate (if stainless steel)
Standards to look for:
EN 1822 (European)
IEST RP-CC001 (US)
ISO 29463
�� Never buy HEPA filters without individual test reports – your cleanroom may fail certification.
Different industries need different filter features.
|
Industry |
Key Requirement |
Recommended Filter |
|
Electronics / Semiconductor |
Low outgassing, ESD safe |
H13 with aluminum separator |
|
Pharmaceutical / GMP |
Stainless steel frame, gel seal |
H14 stainless + gel |
|
Hospital (OR / ICU) |
Low noise, high reliability |
H13 deep-pleat |
|
Food processing |
Washable frame option |
Stainless steel 316 |
|
General manufacturing |
Cost-effective |
H13 galvanized + gasket seal |
Before ordering HEPA filters for FFUs, answer these 5 questions:
What cleanroom class do you need? → ISO 5 (H14) or ISO 6-8 (H13)What is your FFU model / filter dimension? → Check existing filter label
What is your budget? → H13 is 20-30% cheaper than H14
Do you need gel seal or knife edge? → Pharma = gel; General = knife edge
Do you require individual test reports? → Always yes for export projects
At prefabcleanroom.com, we supply replacement HEPA filters for all major FFU brands:
✅ H13 and H14 grades (EN1822 certified)
✅ Standard sizes: 610x610, 1220x610, 1170x570 mm
✅ Gel seal, knife edge, or gasket options
✅ Galvanized steel or stainless steel 304 frames
✅ Individual test report with every filter
✅ Fast shipping worldwide
We work with cleanroom contractors, facility managers, and overseas distributors.
Send us the following information for a quick quote:
Filter size (L x W x H)
Efficiency grade (H13 or H14)
Frame material
Seal type
Quantity
�� Email: sales01@gzkunling.com
�� WhatsApp: +86 13316272504
Volume discounts available for contractors and distributors.
FFU (Fan Filter Unit) for Cleanrooms →
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