Mazzei Venturi Injectors
How does a Venturi work?
Venturis work on a principle of differential pressure.
In short, water flows into the venturi at a higher pressure than that at which it exits. This pressure difference creates a vacuum at the suction port on the side of the device. This sucks air, ozone, or liquid into the main water stream. So, the greater the difference in pressure, the greater the vacuum and, with that, the greater the efficiency of mixing.
If sized and installed correctly, a venturi can achieve a gas/water ratio of 1:1. (i.e. inject 1 litre of air/ozone into every litre of water that passes through it). For liquid dosing, this ratio is a maximum of 1:10 (i.e. inject a maximum of 1 litre of the chemical into every 10 litres of water).
Venturis come in a number of different sizes. Size is determined not by the size of the pipeline into which it is installed, but rather by the pressure and flow rate of the water.
Which Venturi do I need?
Wassertec is an agent for Mazzei Injectors, which are made in the USA.
Mazzei venturi injectors are engineered from highly chemically resistant Kynar (PVDF) and are available in sizes ranging from ½ inch to 12-inch pipe diameter. We keep stock of models in the ½-inch to 3-inch range. Other sizes are available on request.
It is important that a Venturi be correctly sized for any given application. Please contact Wassertec for assistance in this.
Alternatively, please use this guide.
Venturi Performance Tables – Click the Model number for a spec sheet.
Venturi performance is an important factor to consider when purchasing a venturi injector.
Use the venturi performance tables to choose the right venturi for your needs.
| Model | Flow Range (ℓ/min) | Flow Range (ℓ/hr) | Flow @ 3.5 Bar (ℓ/min) | Thread Size | Download |
|---|---|---|---|---|---|
| 287 | 1.1 to 5.25 | 66 to 315 | 3.15 | ½" (12.7mm) | Download |
| 384 | 2.5 to 12.6 | 150 to 756 | 7.60 | ½" (12.7mm) | Download |
| 484 | 3.2 to 23.5 | 192 to 1,410 | 12.3 | ¾" (19.05mm) | Download |
| 584 | 10.6 to 39.7 | 636 to 2,382 | 22.8 | ¾" (19.05mm) | Download |
| 684 | 15.1 to 57.2 | 906 to 3,432 | 38.6 | ¾" (19.05mm) | Download |
| 784 | 16.3 to 80.0 | 978 to 4,800 | 51.6 | ¾" (19.05mm) | Download |
| 978 | 17.0 to 87.1 | 1,020 to 5,226 | 49.2 | 1" (25.4mm) | Download |
| 1078 | 30.3 to 106.7 | 1,818 to 6,402 | 62.1 | 1" (25.4mm) | Download |
| 1583 | 53.8 to 213 | 3,228 to 12,780 | 123 | 1½" (38.1mm) | Download |
| 1584 | 74.9 to 367 | 4,494 to 22,020 | 217 | 1½" (38.1mm) | Download |
| 2081 | 184 to 598 | 11,040 to 35,880 | 375 | 2" (50.8mm) | Download |
| 3090 | 289 to 1238 | 17,340 to 74,280 | 876 | 3" (76.2mm) | Download |
| 4091 | 497 to 1722 | 29,829 to 103,320 | 1572 | 4" (101.6mm) | Download |
Back Pressure
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.
For example:
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.