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Why backflow preventers hinder the function of the ecoturbino and why they must be removed!
Why Backflow Preventers in Shower Fittings Impair the Function of the ecoturbino and Must Be Removed
Our ecoturbino shower adapter is fitted between the tap and shower hose to reduce water consumption and the associated energy costs.
By utilizing a static Venturi turbine, the ecoturbino mixes air into the shower water stream, allowing up to 50% water savings without compromising shower comfort.
The laminar flow of the water, which is necessary for the Venturi effect to be optimised, is a key aspect of the function. However, backflow preventers disrupt this process by making the flow turbulent.
What is a Backflow Preventer?
A backflow preventer is a built-in part in the shower tap outlet that prevents water from flowing back into the main supply line.
The ecoturbino, with its shower hose drainage feature, does not require these components, as the showerhead empties after use.
In shower fittings, the backflow preventer ensures that no contaminated water from the shower re-enters the supply line. Such devices often contain valves, springs, or flaps that block or redirect water flow as needed.
However, these components significantly affect the flow properties of the water and are prone to impurity buildup.
Laminar and Turbulent Water Flow
To understand the impact of backflow preventers on the ecoturbino, the concepts of laminar and turbulent flow must be explained:
- Laminar Water Flow: In laminar flow, water particles move in parallel layers without mixing or cross-currents. This typically occurs in smooth pipes at low velocities. The flow is orderly, and pressure loss remains minimal. Laminar flow is characterized by a low Reynolds number (see Reynolds number Wikipedia) (below approximately 2000), a dimensionless value describing the ratio of inertial to viscous forces.
- Turbulent Water Flow: In contrast, turbulent flow is chaotic, with eddies and mixing between layers. It occurs at higher velocities or in pipes with obstacles and has a higher Reynolds number. Turbulent flow leads to increased energy loss and irregular pressure fluctuations (these fluctuations make the ecoturbino turbine system inoperable).
In water pipes, water typically flows laminarly, especially at the usual flow rates in households.
This orderly flow is essential for the ecoturbino’s function.
The Venturi Effect in Detail
The Venturi effect is a physical principle based on continuity and the Bernoulli equation. When water flows through a constriction, its velocity must increase according to the continuity equation A1·v1 = A2·v2 (where A is the cross-section and v is the velocity) because the cross-section decreases.
According to the Bernoulli equation (see Bernoulli equation Wikipedia) P + ½·ρ·v² + ρ·g·h = constant (where P is pressure, ρ is density, v is velocity, g is gravitational acceleration, and h is height), the pressure drops as velocity increases. This pressure drop creates the vacuum that draws air into the water stream.
A stable, ideally laminar flow is crucial for the Venturi effect.
With laminar flow, the pressure drop is consistent and predictable, enabling efficient air intake.
Turbulent flow, however, causes chaotic pressure fluctuations that disrupt the vacuum and hinder air intake.
How Backflow Preventers Create Turbulence
Backflow preventers disrupt laminar flow due to their design:
- Mechanical Obstacles: Valves and flaps in the backflow preventer force the water to make abrupt directional changes, leading to flow separation and eddy formation.
- Cross-Sectional Changes: Narrow passages or sudden expansions in the backflow preventer alter flow velocity and generate turbulence.
- Moving Parts: Springs or flaps may vibrate during flow, causing additional disturbances in the water stream.
These factors locally increase the Reynolds number, transforming laminar flow into turbulent flow. Even if the water arrives laminarly in the pipes, it leaves the backflow preventer in a chaotic state.
Effects of turbulence on the ecoturbino
When water enters the ecoturbino turbulently, the Venturi turbine cannot generate the required vacuum consistently.
Necessity of Removing Backflow Preventers
To ensure the optimal function of the ecoturbino, backflow preventers must be removed from the shower fitting.
Only then can the laminar flow of water be maintained, which is essential for the Venturi effect.
Without backflow preventers, water flows freely and orderly into the ecoturbino, allowing the turbine to effectively use the vacuum to mix in air. This ensures the system fully realizes its savings potential.
However, it should be noted that removing backflow preventers may raise legal or safety concerns, as they protect drinking water quality.
