This is the most frequent question asked by who asks information about this kind of products.
But unfortunately the answer is the most difficult to give.
Actually we would expect to have a certain value expressed in cubic or square meters as it happens for smoke sensors.
What we can say is that talking about a gas detector, to decide how many sensors we need to place and consequently, the area covered by each one of them depends on a great number of different conditions which can vary according to the environment in which they have to work::