Battery Back Up Devices for Commercial Fire Doors | Cornell

Available for fire door operators with integrated or added optional release device, these devices prevent fire doors from closing due to a power failure.
A Battery Back Up Device for a closing system with an integrated release device also functions as a DC power source to keep local warning devices and detectors up and running during a power outage. 

In addition, you can program the Battery Back Up Device for an integrated release device to cycle the door a selected number of times should the sensing edge contact an obstruction during alarm signal AC power closing.