What is the door release on the fire door?

The fire door closing releaser is a kind of control device (equipment) for normally opening the fire door, which can keep the fire door open. In case of fire, the fire department will automatically close the fire door.

There are usually three kinds of such devices, namely, electromagnetic releaser DSF, electric door closer FMD-2 and thermoelectric dual-control door closer FMD-2(WD). How to choose can be chosen according to the actual situation. Or ask the relevant manufacturers.