2-1 Professional advice
If corrosion is found near the ceiling or in the upper part of the frontside of the fume hood, it that internal gas is leaking to the ceiling side through the top gap between the front sash of the fume hood and the ceiling.
Several causes for this can be considered, but the most common one is when the exhaust air volume of the fume hood is insufficient for the experiments.
Specifically, when an experiment involving heating is performed inside the hood, an ascending air current is formed by hot air. But in the case in which the exhaust air volume is set to be low, the suction power of the exhaust loses to the rising air current and the internal gas escapes to the ceiling part.
In such a case, there is no other solution but to reevaluate the exhaust airflow.
In some cases, such as when the inside of the fume hood is the pathway for the upward airflow that is generated throughout the room, in combination with the heating of the room.
2-1 Advice for Initial support/correspondence
In the case where the upper part of the fume hood's frontside and the ceiling are corroded after a few weeks or months has passed, the cause is most probably one of the following.
In many cases, the direction of the internal gas leaks is from the upper part of the sash to the ceiling.
It can also be because an appropriate exhaust air volume suitable for the experiment has not been set.
Therefore, determine whether the model of the fume hood being used matches the required exhaust air volume for the experiment currently being performed.
Contact the lab manager or the facility administrator to check the specifications and blueprints of the laboratory, including the contents of the instruction manual when the unit was delivered.
The next step is to have an expert look at it. Through the manager of the facility, consult with the company responsible for the construction of the ducts or the fume hood manufacturer.
