Parallel Air Gap Eductors for High Flow Back-flow Prevention
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Solution Overview
Problem
Existing liquid dispensing systems face challenges in achieving high flow rates and preventing back-flow into the inlet supply source, particularly due to the limitations of atmospheric vacuum breakers and single air gap or safe gap eductors, which are bulky, require frequent inspections, and are constrained by elevation requirements, and are inadequate for mixing unstable reagents like chlorine dioxide.
Innovation Solution
The system employs at least two air gap or safe gap eductors in parallel fluid communication with a diluent inlet and additive sources, connected via T connectors, to prevent back-flow and allow for high flow rates without elevation dependency, using a union to combine effluent mixtures for dispensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If atmospheric vacuum breakers are used to prevent back-flow, then back-flow prevention is achieved, but the device becomes bulky, expensive, and requires frequent inspections
Solution Approach 1:
The patent extracts the air inlet valve mechanism from the vacuum breaker assembly, using a separate air gap eductor system instead. This eliminates the complex float cup gasket and bonnet sealing mechanisms while maintaining back-flow prevention through the air gap principle combined with eductor vacuum action.
Solution Approach 2:
The air gap eductor system uses simple, inexpensive components that do not require periodic inspection or replacement like vacuum breaker seals. The system relies on passive air gap geometry and eductor operation rather than wear-prone sealing components.
2Reliability
If atmospheric vacuum breakers are installed, then back-flow prevention is achieved, but the dispenser must be mounted at specific elevation locations
Solution Approach 1:
The air gap acts as an intermediary physical barrier between the liquid supply and the discharge hose outlet. This passive air gap mechanism eliminates the need for elevation-based prevention, allowing the dispenser to be installed at any location regardless of the discharge hose outlet height.
3Reliability
If single air gap or safe gap eductors are used, then back-flow prevention is achieved, but high flow rates cannot be achieved
Solution Approach 1:
The system segments the back-flow prevention function across multiple parallel eductors rather than relying on a single eductor. This allows the system to maintain the back-flow prevention air gap mechanism while achieving high flow rates through the combined capacity of multiple eductors operating simultaneously.
Solution Approach 2:
Multiple eductors are merged in parallel configuration, combining their flow capacities while maintaining the air gap back-flow prevention mechanism. The union combines effluent from multiple eductors, achieving both high flow rate and reliable back-flow prevention.
4Reliability
If atmospheric vacuum breakers are used, then back-flow prevention is achieved, but regular inspections and testing are required
Solution Approach 1:
The air gap eductor system is designed to be self-verifying through its passive air gap mechanism. The physical air gap provides inherent visibility and simplicity that eliminates the need for periodic professional inspection and testing required by vacuum breakers, reducing maintenance time and costs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables efficient, high-flow dispensing without the need for elevation-specific installation and reduces contamination risks, effectively handling unstable reagents by ensuring stable mixing and preventing back-flow into the supply source.
Implementation Method 1
the liquid concentrate is drawn from a source and mixed, via an eductor utilizing venturi action, with a diluent water stream to form the overall diluted detergent or other effluent mixture
Implementation Method 2
utilizes an air inlet valve (i.e., a float cup) that opens during any loss of fluid pressure from a liquid supply. The air inlet valve remains closed by the fluid pressure of the fluid supply. During any loss of such pressure, the air inlet valve opens the air inlet and closes the liquid supply inlet to prevent any back-flow of effluent from the eductor into the liquid supply
Data Source
AI summary
A high-flow liquid dispenser comprises a diluent inlet connectable to a pressurized liquid source and a backflow preventer and eductor system in fluid communication with the diluent inlet and defining a dispenser outlet for dispensing the effluent mixture. The backflow preventer and eductor system comprises at least two air gap or safe gap eductors in simultaneous fluid communication with the diluent inlet.