Register Your Interest In Our CFD Testing services
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Clean Air Wins Sustainability Award
at Lab Innovations 2024
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01204 572 900
Clean Air has developed a new method of CFD testing and fume cupboard certification that does not use the environmentally damaging SF6.
Register Your Interest In Our CFD Testing services
Our friendly, professional team is waiting to help you with all your enquiries.
We offer affordable Computational Fluid Dynamics (CFD) based testing for our entire range of fume cupboards. This innovative approach combines computer-aided engineering techniques with practical measurements to ensure the fume cupboard performs well on site.
Our new test method will help us reduce our carbon footprint by saving around 200 tonnes of CO2e per year, thanks to our testing and product development work!
| SF6 Gas Test | CFD Testing | |
| Typical number of measurements for containment | 1,890 | >1 Trillion – 1 million cells at 100Hz for 30s |
| Environmental impact | 3,000 kg CO2e | 0 kg CO2e |
| Physical inspections | ✅ | ✅ |
| Assesses gas escaping in normal conditions | ✅ | ✅ |
| Assesses how quickly the chamber is purged | ✅* | ✅ |
| Assesses the impact of a person walking in front of the fume cupboard | ✅* | ✅ |
| Highly repeatable | ❌ | ✅ |
| Full visualisation of results | ❌ | ✅ |
| Can test with equipment inside | ❌ | ✅ |
| * Approximations must be made |
The test starts by running the simulation for 1 residence time. This provides sufficient time for the normal airflow structure around the fume cupboard to form.After the first residence time, the volume inside the fume cupboard assumes a completely contaminated state and remains contaminated thereafter. The simulation continues for 2 more residence times, and the average contaminant that escapes the fume cupboard into an area where an operator may be working is calculated.The face velocity and breakout rate are then reported. The face velocity profile forms the baseline for on-site testing.
The test starts by simulating for 1 residence time. This allows the normal airflow structure around the fume cupboard to form.
Afterwards, the air within the fume cupboard is contaminated to 100% and allowed to clear. After 1 residence time, from when the fume cupboard is contaminated, the percentage of uncontaminated air is reported across the fume cupboard’s working region. This is known as the clearance factor.
The simulation will continue for 30 seconds after the gas is initially contaminated. The concentration of contaminated air will fall according to a log-linear relationship. From this relationship, the time taken for the entire fume cupboard to remove 99.9% of contaminated air is reported as the clearance time.
The test starts by simulating for 1 residence time. This allows the normal airflow structure around the fume cupboard to form.
Next, the fume cupboard volume is contaminated to a concentration of 20ppm from 100 mm, 150 mm and 200 mm inside the working region. The contamination is continuously renewed, so the working region always contains 20ppm. If you know the concentration you will encounter within the fume cupboard we can test at the expected concentrations too.
For over two and a half years, our expert engineers have teamed up with academics at Manchester Metropolitan University to prove the accuracy of CFD in the context of fume cupboards. A summary of the research can be found in our white paper or through their scientific publication.
The research team comprised three engineers, each with relevant PhDs and a professor, bringing together decades of experience in fluid mechanics and experimental testing.
After the Design Test is complete, we conduct on-site testing, which includes practical aspects such as the illumination of the workspace and noise, but also velocity profiling to check how well a fume cupboard performs in the customer’s laboratory.The On-Site test uses our bespoke measuring system, FlowChex, which measures 162,000 data points across the fume cupboard to ensure that the fume cupboard is performing as designed. The face velocity measured in situ iscompared to a safe limit taken from the CFD tests. The velocity is thoroughly assessed against multiple criteria to ensure both the average and instantaneous velocities are safe.On Site testing also includes measurements of the face velocity when the sash is opened from fully closed to the working height. The time taken for the face velocity to return to normal is then reported.
