... class and two class separator,special pump,electric control box,oil content data recorder monitor,automaticValve,inspect system ... transmit alarm signal,change valve(N.O,N.C solenoid valve)operating,first stage discharging water enter ... ,close the N.O port,open the N.c port,bilge water enter into the separator temporarily ... water(F.W)enter pump suction through N.C port from pump outlet,to be back-flushing ...