Using Foam Eductors: Know How It Works?

The Venturi Principal is used by Foam Educators. The inlet of the eductor has a great diameter compared to the small diameter in the unit's center or Venturi area. The Eductors outlet returns to the diameter of the original inlet. The consequence is all the water that enters the eductor is pushed through the opening of the small centre. The speed of water must increase in small diameters in order for this to occur. The increase in velocity decreases pressure in the Venturi region, allowing the foam concentrate to enter the water stream as the atmospheric pressure in the foam bucket or tank pushes on the concentrate. The same idea is used by the carburetors for engines and the aircraft wings for the lifting.

The pipelines can be fastened directly to the discharge in various sizes, typically between 60 gpm and 250 gpm. They can also be placed in the discharge line between two hose sections. It may be necessary to move the Eductors to the hoseline if a long line is pumped; as the amount of hose can go past the eductor is limited. Depending on the eductor, such limitations vary from 150 to 300 feet.

If the discharge plumbing causes friction that reaches the Eductors, the eductor may also need to be moved away from the discharge. Such turbulence might disrupt the Venturi's operation.

Remember they are situation-sensitive when using foam Eductors. To operate effectively they must be operated in precisely the correct parameters. The flow through the Eductor, for example, has to match its ranking. Drastic variations and/or incorrect flow may impact the drop in pressure through the Venturi, thereby preventing its operation. It is also important to adapt the eductor to the correctly calibrated nozzle, which must discharge at a constant rate.