An air injector utilizing a venturi nozzle is used to add air to a water system to remove Sulfur, H2S, or other smelly substances. A standard air over water galvanized type pressure tank is used, instead of a bladder tank, to allow the air to mix with the water. A float operated Air Volume Control installed ½ way on the side of the tank releases any excess air to prevent the air from entering the pipe lines or house. A venturi air injector needs a certain amount of flow to produce the pressure differential across the venturi that draws in the air. When used with a Cycle Stop Valve, the flow being used determines the flow coming through the venturi. If a low flow rate such as 1 to 5 GPM is being used for long periods of time, the venturi will not draw air. When large enough flow rates are being used, the venturi draws in air as usual. When water is used intermittently as for use in the home, it is important that most of the water stored in the pressure tank be mixed with the correct amount of air. When the pressure increases to the setting of the Cycle Stop Valve, the flow is reduced to 1 GPM, which is not enough to allow the venturi to draw in air. Therefore, the setting of the Cycle Stop Valve should be as close as possible to the off pressure of the pressure switch. In other words, if you have a 60 PSI Cycle Stop Valve, the pressure switch setting needs to be about 43/63. In this way the tank is filled at the maximum rate the pump can produce, and the air injector is working until the pressure reaches 60 PSI. Most of the tank is then filled with water and mixed with air, and only the last couple of gallons of water will enter the tank without air as the CSV reduces the flow rate to 1 GPM. Above 60 PSI the flow rate is too low for the venturi to function but, the tank is already almost full and the pressure switch quickly shuts the pump off at 63 PSI and leaves plenty of air in the tank.
