F9 Pocket / Bag Filters: EN779 Certified Secondary Filtration for AHU and HVAC
The Airtech F9 pocket filter is engineered for AHU secondary stage filtration. Synthetic moisture-resistant media in a galvanised steel frame with aluminium pocket supports, available in 330mm and 600mm pocket depths. EN779-certified to F9 grade at ≥95% efficiency at 0.4µm: captures PM2.5, fine dust, and diesel combustion aerosols. Standard sizes held in stock at our Silverton warehouse; call with your AHU frame size and we confirm availability same day.
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The Airtech F9 pocket filter is engineered for AHU secondary stage filtration. Multi-pocket synthetic media in a galvanised steel frame with aluminium pocket supports, available in 330mm and 600mm pocket depths. EN779-certified to F9 grade at ≥95% average efficiency at 0.4µm, capturing PM2.5, diesel combustion aerosols, and the fine dust that G4 pre-filters pass through. Stock held in Pretoria for same/next-day supply to HVAC maintenance contractors.
Why Secondary Filtration Matters
F9 pocket filters are the filter stage that determines indoor air quality. Where G4 panel filters protect the AHU from coarse loading, the F9 pocket filter removes the fine particulate fraction that reaches occupants and sensitive equipment. At ≥95% efficiency at 0.4µm, F9 captures PM2.5, diesel combustion by-products, and sub-micron dust: the contaminants linked to respiratory and cardiovascular health outcomes in commercial building environments.
Without adequate F9 secondary filtration, fine particulate bypasses the AHU entirely and circulates through occupied spaces. In hospitals, pharmaceutical facilities, and high-specification commercial buildings, F9 is the minimum standard for secondary filtration. In critical environments, F9 also serves as the pre-filter protecting downstream HEPA terminal filters from overloading, extending HEPA service life and reducing replacement costs significantly.
The Airtech F9 pocket filter is specified to protect your occupants, your equipment, and your HEPA investment downstream. Not washable. Replace at 400–450 Pa final resistance.
Specification: 595×595×330mm (6-pocket)
| Filter Class | F9 (EN779:2012) |
| Standard Size (330mm) | 595 × 595 × 330 mm (6-pocket) |
| Narrow Size (330mm) | 295 × 595 × 330 mm (4-pocket) |
| Deep Format (600mm) | 595 × 595 × 600 mm (6-pocket) |
| Media Type | Synthetic moisture-resistant |
| Frame | Galvanised steel + aluminium pocket supports |
| Initial Resistance (595×595×330) | 225 Pa ±10% at 3 400 m³/h |
| Initial Resistance (295×595×330) | 185 Pa ±10% at 1 700 m³/h |
| Initial Resistance (595×595×600) | 105 Pa ±10% at 3 400 m³/h |
| Final Resistance | 400–450 Pa (replace at this reading) |
| Avg. Efficiency | F9 ≥ 95% at 0.4 µm (captures PM2.5) |
| Washable | No |
| Weight (595×595×330) | 1.7 kg |
| Weight (295×595×330) | 1.15 kg |
| Replacement Interval | 6–12 months depending on pre-filtration and load |
Resistance vs Airflow: 595×595×330mm (6-pocket)
| Airflow (m³/h) | 1500 | 2000 | 2500 | 3000 | 3400 | 4000 | 4500 | 5000 |
|---|---|---|---|---|---|---|---|---|
| Resistance (Pa) | 95 | 125 | 160 | 195 | 222 | 266 | 305 | 345 |
Resistance vs Airflow: 595×595×600mm Deep (6-pocket)
| Airflow (m³/h) | 1500 | 2000 | 2500 | 3000 | 3400 | 4000 | 4500 | 5000 |
|---|---|---|---|---|---|---|---|---|
| Resistance (Pa) | 45 | 60 | 75 | 92 | 106 | 130 | 150 | 170 |
Available Sizes: All F9, EN779:2012
| Size (WxHxD) | Pockets | Init. Resistance | Rated Airflow | Pcs/Carton |
|---|---|---|---|---|
| 595×595×330mm | 6 | 225Pa ±10% | 3400 m³/h | 9 |
| 295×595×330mm | 4 | 185Pa ±10% | 1700 m³/h | 16 |
| 595×595×600mm | 6 | 105Pa ±10% | 3400 m³/h | 6 |
All: Galvanised steel frame, synthetic moisture-resistant media, F9 EN779:2012. Final resistance: 400–450 Pa. Not washable.
F9 pocket filters are the secondary filtration stage in commercial HVAC air handling units. At ≥95% average efficiency at 0.4µm, F9 captures PM2.5, diesel combustion aerosols, and fine dust that G4 pre-filters pass through. Specified wherever occupant health, regulatory compliance, or downstream equipment protection demands more than coarse filtration alone.
IAQ compliance and occupant comfort in high-occupancy buildings. F9 is the secondary filter standard for most commercial HVAC specifications in South Africa, removing fine particulate before it reaches occupied zones.
Secondary filtration upstream of H14 HEPA terminal filters in operating theatre and critical care AHU systems. F9 extends HEPA service life by removing fine particulate before it reaches the terminal filter.
Pre-HEPA filtration in GMP Grade B and C cleanroom air handling systems. F9 extends HEPA service life and protects production areas from fine contaminant ingress in pharmaceutical and life sciences facilities.
ASHRAE TC 9.9 recommends F9-equivalent filtration for data centre air handling. F9 pocket filters protect sensitive electronics from fine particulate contamination while delivering lower pressure drop than equivalent HEPA filtration.
High-traffic buildings where indoor air quality and energy efficiency are both priorities. F9 provides the filtration performance required for healthy learning and guest environments without the pressure-drop penalty of HEPA.
Critical infrastructure environments where fine particulate contamination can cause electronic component failure. F9 secondary filtration protects switchgear and control systems in high-dust industrial settings.
What is an F9 pocket/bag filter used for?
F9 pocket filters are the secondary filtration stage in commercial HVAC air handling units. They capture fine particulate, PM2.5, diesel combustion aerosols, and sub-micron dust that G4 pre-filters allow through. At ≥95% average efficiency at 0.4µm, they determine indoor air quality in offices, hospitals, pharmaceutical plants, and data centres.
How often should F9 pocket filters be replaced?
Typically every 6–12 months in commercial HVAC, depending on system load and pre-filtration quality. Replace when differential pressure reaches 400–450 Pa. On the Highveld where dust loads are high, replace closer to the 6-month mark. Well-maintained G4 pre-filters significantly extend F9 service life.
What is the difference between 330mm and 600mm pocket depth?
The 330mm depth is the standard format for most commercial AHUs. The 600mm deep pocket filter offers lower initial resistance (105 Pa vs 225 Pa at 3 400 m³/h) and a larger media surface area, which extends service life and reduces energy consumption. The 600mm format is preferred in high-airflow systems or where energy efficiency is a priority.
Why do I need both G4 pre-filters and F9 pocket filters?
G4 panel filters remove coarse dust, insects, and fibres before they reach the F9 stage. Without adequate pre-filtration, the F9 pockets load rapidly with coarse material, dramatically shortening their service life. A properly maintained G4 pre-filter means your F9 bags last their full service interval. Neglect the G4 and you are replacing expensive F9 filtration two to three times more often.
Do you deliver pocket filters nationwide?
Yes, delivery is available nationwide across South Africa. Free delivery on all orders. Stock is held at our Silverton, Pretoria warehouse with same/next-day despatch on standard sizes. Call +27 74 159 1634 to confirm availability before ordering.
What certification do your F9 filters have?
Tested and classified to EN779:2012 F9 grade with average efficiency of ≥95% at 0.4µm. CNAS-accredited lab test certificates are available on request. F9 is the South African commercial HVAC standard for secondary AHU filtration.