Washing Machine Air Break Design to Prevent Backflow Contamination
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Solution Overview
Problem
Laundry washing machines face challenges in preventing backflow of non-potable water from the drainage system into the water supply, which can lead to contamination and violate safety standards like EN61770, especially when there is a failure in the pump or valve systems.
Innovation Solution
The implementation of a back-siphonage mitigation air break system, where an auxiliary conduit and collection vessel are arranged to create an air gap between the inlet and outlet sections, preventing water from flowing back into the fresh water supply by directing it to a collection vessel or hose outside the washing machine, ensuring that any backflow from the drainage system is diverted without contaminating the water supply unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pump unit is used to pump out water from the tub to the drainage system, then water discharge function is improved, but risk of backflow contamination increases
Solution Approach 1:
An air break chamber is introduced as an intermediary component between the pump unit and the drainage system. This chamber creates a physical air gap that prevents direct fluid communication, allowing the pump to discharge water effectively while blocking the pathway for contaminated drainage water to flow back into the fresh water supply system.
Solution Approach 2:
The water discharge system is segmented into separate zones: a fresh water supply zone, an air break chamber zone, and a drainage discharge zone. This segmentation isolates the potable water system from the contaminated drainage system, maintaining functional water discharge capability while eliminating backflow contamination risk through physical separation.
2Ease of operation
If a valve is used to isolate the fresh water feeding plant from the drum, then water supply control is improved, but vulnerability to back-siphonage increases
Solution Approach 1:
An air break chamber serves as a mediator between the valve-controlled fresh water supply system and the drainage system. This intermediary component maintains the effectiveness of valve control for water supply while providing passive protection against back-siphonage through its air gap mechanism, which prevents pressure differentials from forcing contaminated water back through the valve.
Solution Approach 2:
The air break chamber provides beforehand cushioning by creating a physical barrier that anticipates and prevents back-siphonage before it can occur. The air gap acts as a pre-established protective measure that neutralizes potential pressure differentials and contamination risks before they can affect the fresh water supply system.
3Device complexity
If direct connection is made between the water supply unit and drainage system, then device complexity is reduced, but contamination risk increases
Solution Approach 1:
An air break chamber is introduced as a simple intermediary component that connects the water supply unit and drainage system while preventing contamination. This single component adds minimal complexity to the overall system structure but effectively eliminates the harmful backflow contamination risk by creating a physical air barrier between the two systems.
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 solution effectively prevents contamination of the fresh water supply, enhancing safety and compliance with stringent standards by ensuring that any backflow from the drainage system is safely diverted, thus maintaining the integrity of the water supply and reducing the risk of biological contamination.
Implementation Method 1
a back-siphonage mitigation air break (S) is present between an inlet opening (6a) of the collection vessel or hose (6) and the outlet section (11e) of the auxiliary conduit (11), the back siphonage mitigation air break (S) being configured to mitigate back-siphonage from said drainage system (20) by causing water that may flow back from the drainage system (20) to the collection vessel or hose (6)
Data Source
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AI summary
The present disclosure refers to a washing machine (1) configured for washing laundry, the washing machine (1) comprising a tub (2) suitable for collecting water, a water supply unit (3) configured to feed fresh water from a water supply network to the tub (2), a washing agents dispenser (4) configured to feed at least one washing agent, in particular a detergent, to the tub (2), the washing agents dispenser (4) being connected downstream the water supply unit (3) and at least one pump (5) configured to pump out the water from the tub (2) to a drainage system (20) outside the washing machine (1). The water supply unit (3) comprises a water draining device (10) configured to drain a residual water to a collection vessel or hose (6) operatively connected to the tub (2) and to the exterior of the washing machine (1). The water draining device (10) comprises at least an auxiliary conduit (11) comprising an outlet section (11e) feeding the residual water to the collection vessel or hose (6). The auxiliary conduit (11) and the collection vessel or hose (6) are arranged in a predetermined spatial configuration such that a back-siphonage mitigation air break (S) is present between an inlet opening (6a) of the collection vessel or hose (6) and the outlet section (11e) of the auxiliary conduit (11), the back siphonage mitigation air break (S) being configured to mitigate back-siphonage from said drainage system (20) by causing water that may flow back from the drainage system (20) to the collection vessel or hose (6) and/or that may reach an overflow level within said tub (2) to come out at the back-siphonage mitigation air break (S) without climbing back to the auxiliary conduit (11).