Description
Overview
B1 is specified by laboratories that cannot justify two cabinets: the work is biological, but the protocol occasionally involves a volatile toxic chemical, and an A2 cabinet would recirculate it back over the work surface.
The cabinet sends about seventy per cent of its air to a dedicated duct and recirculates the rest. A pressure sensor holds that split as the filters load. The remaining recirculation is why B1 is limited to small volumes — it is a mixed-exhaust compromise, not a total-exhaust solution.
If the chemistry is incidental, B1 works and costs less to install than B2. If the chemistry is the point, specify B2.
Key features
- 70/30 split held by pressure control. The exhaust fraction does not drift as the supply and exhaust filters load at different rates.
- Smaller duct than B2. About a third less exhaust volume than a total-exhaust cabinet of the same width, which reduces make-up air and duct size.
- Pressure sensor with alarms. Duct static, downflow and inflow are monitored; the alarm tells you which side moved.
- ULPA on both paths. Supply and exhaust filters are U15, so the recirculated fraction is as clean as the supply air.
Specifications
| Airflow class | Class II Type B1 — about 70% ducted exhaust, 30% recirculated |
|---|---|
| Downflow velocity | 0.33 ± 0.025 m/s |
| Inflow velocity | 0.53 ± 0.025 m/s |
| Exhaust connection | Dedicated duct, 4 in / 100 mm collar |
| Filter | ULPA U15, 99.9995% at 0.12 µm, supply and exhaust |
| Working width | 4 ft / 1.2 m |
| External dimensions | 1300 × 800 × 2250 mm (W × D × H) |
| Internal dimensions | 1150 × 600 × 660 mm (W × D × H) |
| Power | 1800 VA maximum, 230V single phase |
| Noise | ≤65 dB(A) |
| Certification | CE, UKCA, EN 12469 |
Where you would install it
- Radiolabelling and tracers. Small-volume volatile work inside a biological protocol.
- Method development. Solvent handling that does not justify a second, dedicated cabinet.
- Process development. Pilot work where the chemistry is incidental to the biology.
Frequently asked questions
How much chemical can I evaporate in a B1?
Treat it as small-volume work. The recirculated 30% carries a fraction of the vapour back over the work surface, so the exhausted volume — not the cabinet size — sets the limit.
Can the duct be shared with a fume hood?
No. A shared manifold makes the exhaust split unstable and the cabinet will alarm. Run a dedicated duct.
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