Automatic vacuum switch works in semi-automatic and automatic systems with two chlorine cylinders and it is designed to secure uninterrupted operation and chlorine supply. Its design allows to switch over the chlorine supply from the second cylinder at the time of complete discharge of the first one. By doing so, not only a continuous feed, but a smooth exchange of empty tanks is secured. They are made in capacities up to 4 kg/h and up to 10 kg/h.