We can usually see a vision panel on a fire door, when do we actually need it?
There are some conditions that the passengers need to see each other from both sides. For example, when passengers are going though a double leaf fire door from both ways, when people from push sides can see the person from pull side, it’s getting easier from hurting the people from pull side. Usually a fire door are push to open with a high speed, if people couldn’t see the other from other side, hurt occurs some time.
Also a vision panel appears on a single door which has a high crowd of passengers, a door which being open very often from both sides installed with a vision panel will provide pretty well usage for passengers from both way.
Some public areas are open to vision panels as well such school, hospital or government offices. People from outside can have a great vision of the people inside to decide whether it’s a good timing to enter.
Certainly a vision panel on fire door should be fire rated and certified by a well known third party such as UL, Intertek, BM TRADA and etc.