Published on 23rd February 2026
By Dr Andrew Manning CEng MIMechE
BS 7989 is now obsolete.
In November 2025, the British and European Standards Committees for laboratory furniture and equipment published an important new standard: BS EN 17242.
This change signals a significant shift in guidance for laboratories using recirculating filtration fume cupboards. For anyone responsible for lab safety, chemical containment, or specifying new fume cupboards, the new standard introduces clearer expectations around filter performance, testing, and user information.
BS EN 17242 applies only to new recirculating fume cupboards installed after November 2025, but these guidelines deliver a new benchmark for filtered unit best practice across the sector.
The new standard replaces BS 7989, which was the British Standard for all fume cupboards and cabinets before the introduction of EN 14175 took precedence over the fume cupboards in 2001. BS 7989 remained in force for its contribution to fume cabinets but has been withdrawn from circulation since November 2025.
One of the key changes is terminology.
In the UK, industrial recirculating units are now officially referred to as fume cabinets. This removes long-standing ambiguity between ducted fume cupboards and recirculating filtration systems, which operate very differently.
A ducted fume cupboard extracts air to the outside environment. A recirculating fume cabinet filters the air and returns it back into the laboratory.
That distinction matters, because the safety of a recirculating system depends entirely on correct filtration.
A recirculating fume cabinet removes contaminated air from the work chamber, passes it through a filter, and then releases the cleaned air back into the lab.
This means the filter must be:
BS EN 17242 brings stronger guidance to ensure lab personnel remain protected when using recirculating fume cupboards.
The new standard requires clear information on which chemicals are compatible with the filter installed in the fume cabinet.
This information is provided by the filter supplier and must be updated if the filter is replaced. It must also be clearly displayed on the front of the fume cabinet, helping users make informed decisions and supporting safe day-to-day operation.
To help laboratories select the correct equipment, BS EN 17242 introduces a three-part classification system in the form X/Y/Z.
X refers to the filter arrangement:
Y refers to the filtration type:
Z refers to continuous monitoring:
For example, an A/2/1 fume cabinet would have a built-in activated carbon filter with continuous monitoring.
This system improves clarity and supports more consistent specification based on risk assessment.
BS EN 17242 places greater emphasis on continuous monitoring as a safety feature.
Where installed, monitoring systems can detect chemical breakthrough at the filter outlet and trigger an alarm if contaminants are present.
If continuous monitoring is not fitted, sampling ports must be included either side of the filter so that portable gas detection equipment can be connected easily to test filter integrity.
This reflects a growing focus on verification, not just installation.
The standard introduces two key testing approaches: filtration testing and containment testing.
The aim of filtration testing is to understand how long a filter may last under controlled conditions.
A challenge gas is released inside the fume cabinet at a constant rate, while downstream concentrations are monitored continuously. When the concentration begins to rise, this indicates filter breakthrough.
On-site testing can confirm whether a filter is working at that moment in time, but it cannot estimate how much service life remains.
Containment testing for ducted fume cupboards under BS EN 14175-3 traditionally uses SF₆.
However, SF₆ has a high global warming potential (GWP 24,300) and cannot be removed by filtration. For this reason, BS EN 17242 uses Isopropyl Alcohol (IPA) instead.
Currently, there is no published correlation between containment results using IPA and those using SF₆, which makes direct comparison between ducted and recirculating systems more difficult. This is noted in the foreword of the British Standard.
BS EN 17242 represents an important step forward for recirculating fume cupboards and fume cabinets. It brings:
For laboratories using recirculating filtration technology, the standard reinforces the importance of correct filter selection, risk assessment, and ongoing safety verification.
If you would like support understanding what BS EN 17242 means for your fume cupboard installation or lab safety processes, Clean Air can help.
Andy has a master’s degree in Marine Engineering from Newcastle University and a PhD from Northumbria University, graduating in 2022. He previously worked for the MoD in testing and inspection of HMS Queen Elizabeth during its construction and sea trials and was also an equipment specialist for chilled water and ventilation systems.
