... no corrode, the life long The feature of fireproof control valve FFH-2, control valve,discharge fume valveIt is applicable to air vents of ... occurs when indoor forms the positive pressure before.SD,DC24V,0.5A.Uses the SD control device, power source DC24V,0.5A ... the room, the fire occurs indoor forms the positive pressure before. May control in the room.BSD,DC24V,0.5A.,DC24V. PYK ...