Click the Model number below to view the spec sheet (in PDF format):
Understanding the Venturi Performance Tables
Increasing the back pressure on the outlet side of a Venturi decreases the Suction as this reduces the difference in pressure between the Inlet and the Outlet.
If the back pressure on a Venturi is close to Zero (ie. the water flowing out of the Venturi goes straight into the top of a tank) then the Venturi will give maximum suction.
Alternatively if the water exiting the Venturi still has to travel say 10 metres uphill then there will be 1 Bar back pressure. This will reduce the available suction. The Venturi tables allow us to calculate how much suction a venturi will generate under varying conditions.
Venturi Performance Tables Explained
Each model Venturi has a corresponding venturi performance table.
The excerpt left is from a Model 784 venturi and is for Air Suction. If you are dosing a liquid then use the table marked “Liquid Suction”.
The Table is divided into Sections:
- Injector Inlet – This is the pressure of water entering the venturi
- Injector Outlet – This is the back pressure on the outlet of the venturi
- Motive Flow – This is the volume of water the venturi can process at the corresponding inlet pressure. The higher the pressure the higher the motive flow.
- Air Suction – This is the maximum air suction corresponding to the amount of back pressure. Notice how as the back pressure (Outlet) increases the suction decreases.
Example (Highlighted in Blue):
With 4.22 Bar (kg/cm²) inlet pressure and 1.05 Bar outlet pressure (i.e. 10 metre head of water), the Model 784 venturi will allow 56.6 litres of water through and create a suction of 20.8 litres per minute of air/gas/ozone.
If the back pressure was Zero then the suction would be 28.0 litres per minute.