The venturi injector uses a pressure differential between the inlet and outlet to create suction. This requires no moving parts for incredible reliability. It requires about a 25% difference to start suction.
To make sure the venturi will be able to operate on your system, you need to know your operating pressure and flow required for your driptape or sprinklers. The pressure of your system will determine the flow needed. First, find the pressure on the far left of the chart that is closest to yours. Based off that pressure, the chart will tell you the motive flow required for each size of injector to create suction. For example, if you had 50PSI you would need 8.7gpm with a 3/4" injector, for a 1" injector you would need 25gpm of flow through the injector and so forth. Without the proper flow at the given inlet pressure the Venturi will not create suction.
The injector should be installed horizontally. It can be installed vertically but the outlet must be on top to not trap air. It can either be installed in-line with your water source or it can also be installed around any point of restriction that creates a pressure loss, like a valve that can be closed slightly.
If using the injector for a drip system make sure your flow while running meets the minimum required for the injector to create suction. The minimum will change based on your inlet pressure. The best way to size an injector is off the suction rate needed for the ratio of fertilizer desired.
