The bee escape is inserted between the brood chamber and the honey chamber(s). Bees located in the honey chamber can pass through the escape into the brood chamber, however the bees found in the brood chamber cannot go up throught the valve into the honey chamber and remain there. Thus, the honey chamber is emptied of bees and you can easily harvest without disturbing the bees or being disturbed by them.
For the valve to operate, it is necessary that the queen is in the brood chamber, and that there is no brood in the honey chamber, since in such a case bees will not leave it. It is recommended that a queen excluder (ref.AN51401-4) is used at least three weeks prior to the introduction of the escape valve.
Just insert the valve between the brood and honey chambers to achieve full evacuation within 1-2 days.