Second-stage filtration that protects your HEPA filters
A bag filter (pocket filter) is a common second-stage element in central air conditioning and cleanroom ventilation systems. It is installed in the middle section of the air handling unit (AHU) and captures suspended particles of 1–5 µm, acting as a pre-filter for the HEPA filter, greatly extending HEPA life and lowering replacement costs.
The bag design gives a very large face area: compared with panel filters of the same frame size, it holds more dust with lower resistance. Metal spacers between the bags keep them from rubbing and tearing at high air speeds, and the bag edges are ultrasonically welded for airtightness and strength.
Efficiency classes (with reference to EN 779)
Bag filters are classed from F5 to F9. Higher classes capture finer particles but also have higher resistance. Choose by the cleanroom class you need and the pressure drop your air system can take.
| Class | Efficiency (colorimetric) | Particle size | Typical bag color (European) | Typical use |
|---|---|---|---|---|
| F5 | 40–50% @ 1.0 µm | ≥ 1 µm | White | General commercial buildings |
| F6 | 60–70% @ 1.0 µm | ≥ 1 µm | Green | Hospitals, food plants |
| F7 | 80–85% @ 1.0 µm | ≥ 1 µm | Pink | Electronics and pharmaceutical plants |
| F8 | 90–95% @ 1.0 µm | ≥ 1 µm | Light yellow | Semiconductor fabs, cleanroom pre-filtration |
| F9 | ≥ 95% @ 0.5 µm | ≥ 0.5 µm | White | High-class cleanroom pre-filtration |
Specifications
| Item | Details |
|---|---|
| Media | Synthetic fiber nonwoven / glass fiber (depending on class) |
| Frame | Aluminum alloy / galvanized steel / stainless steel |
| Bags | 3 / 5 / 6 / 8 bags (depending on frame size) |
| Guard mesh | Galvanized wire mesh / expanded aluminum mesh |
| Max. temperature | 70–80°C (depending on media) |
| Max. humidity | 90% RH (non-condensing) |
| Recommended final resistance | ≤ 300–400 Pa (replace at this value) |
| Replacement interval | Approx. 3–4 months (depending on dust load) |
| Stock sizes | 590 mm H × 290 mm W × 95 mm D; 24 in. H × 24 in. W × 30 in. |
| Custom | Non-standard sizes available |
Notes
- Bag filters cannot be washed — washing removes the filter media. Replace the whole filter when it reaches final resistance. High dust loads shorten the replacement interval.
- Before ordering, please confirm frame size (L × W × D), efficiency class and number of bags, or send us the air handling unit model and we can help match.
When you request a quote, please tell us: frame size, efficiency class, number of bags, frame material and quantity.
Email us for a quote: [email protected]