Variable air volume fume hoods

This fume hood works automatically when the sash is opened.

When the sash is lowered, a small air flow keeps the interior of the fume hood continuously ventilated (200 hourly changes).

The air flow rate is adjusted as required according to the height of the sash between the lowest position (minimum flow rate) and the maximum working height (maximum flow rate).

There is nothing to do, but it is imperative before any use to check that your fume hood is working properly (the green light is on).

Normal flow Indicator

In the event of a malfunction, the red light flashes

If you go above the maximum working height, the flow rate no longer changes and your protection drops very quickly with the opening.

Decrease the height of the sash and press Vmax.

You significantly increase the speed of air entering the fume hood.

By reducing the opening by 10 cm for example, the containment performance is greatly improved.

Remember  that anything that impedes the flow of air will reduce the efficiency of the fume hood.


Pressing Vmin reduces the speed to the lowest even regardless of the height of the sash.

Beware, the fume hood is much less efficient and only partially protects you.

The green or blue QCSL 3 (Qualified for Chemical Safety Level 3) logo indicates that the containment performance has been validated for a working height of 50 cm (green) or 40 cm (blue).

All questions about the qualification of fume hoods

If you work with the sash above this height, the protection level is no longer guaranteed.

A fume hood is an open device that does not fully protect you.

Don’t forget best practices.

Ask [email protected] if you have special activities and for any questions on user protection using fume hoods.

We introduced the qualification concept at the end of 2021.

All 900 fume hoods on the Campus will be qualified every 5 years and by 2024 they will all have been checked once. This is in addition to all the maintenance work that ensures that the fume hoods are functioning at their best according to the Swiss standard.

If you have any doubts about the level of protection provided by your fume hood in relation to your activities, contact [email protected]. For breakdowns and defects, you must contact the Alarm and Engagement Center (CAE) 34000