Functions: 1.Used in ventilation system.Valve closes down automatically at 70 degree 2.Used in fire exhausting system,Valve closes down automatically at 280 degree 3.Returned originally by hand. The closure and opening angle is from 0~90 degree. 4.Output valve action signal,and associate with concerned equipment to operate. Characteristics: 1.Control source voltage is DC24V?0%,and electric current is not above 0.4A. 2.Can be equipped independent control box to realize long-distance control. 3.Can be connect in series to control many. 4. Have flawlessel ectrical machine protection divice.