Abstract: According to the invention there is provided a gas chlorinator with reduced number of components, having a chlorinator housing consisting of a front and a back body forming an interior cavity, a diaphragm assembly disposed between the front and back body dividing the cavity into a front chamber and a back chamber, a chlorine inlet in the back body connecting the back chamber with a chlorine source, a chlorine flow valve in the inlet in operative engagement with the diaphragm assembly for controlling flow of chlorine into the back chamber, a chlorine outlet connecting the back chamber with a vacuum source for activating the diaphragm assembly to supply chlorine to the vacuum source via the chlorine inlet and the flow valve. According to a further feature, the gas chlorinator has matching screw threads formed in the front and back body for threadedly joining the front and back body.