Backflow Preventer Testing via Absolute Pressure Measurement
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Solution Overview
Problem
Current methods for testing backflow preventer assemblies are complex, costly, and require differential pressure meters, making them cumbersome and prone to user error due to the need for specific conduit attachment orders.
Innovation Solution
A simplified testing method using a backflow preventer assembly with an upstream and downstream check valve assembly, an intermediate chamber, and a relief valve, where testing is performed by measuring absolute pressures with a manometer attached to a single test cock, eliminating the need for differential pressure meters and reducing the complexity of attachment orders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a differential pressure meter is used to test the backflow preventer assembly, then the testing accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The testing method is divided into separate sequential steps: first measuring absolute pressure upstream of the check valve, then measuring absolute pressure downstream. This segmentation allows using simple absolute pressure meters instead of a complex differential pressure meter, while maintaining testing accuracy through comparative measurement.
Solution Approach 2:
The patent introduces an intermediary approach by using a single test cock that connects to both measurement points sequentially. This intermediary connection method eliminates the need for multiple simultaneous pressure measurement ports and complex differential pressure instrumentation.
2Measurement precision
If a differential pressure meter with multiple conduits is used, then the measurement capability is improved, but the ease of operation deteriorates due to the need for specific attachment orders
Solution Approach 1:
A single test cock is designed to serve multiple functions: it can be connected to the upstream side for first measurement, then reconnected to the downstream side for second measurement. This universal test cock eliminates the need for multiple specialized connection points and simplifies the operator's task.
Solution Approach 2:
Instead of having multiple conduits that need to be connected in a specific order to a differential pressure meter, the patent inverts the approach by having a single conduit (test cock) that is sequentially connected to different measurement points. This reversal of the connection paradigm simplifies operation.
3Adaptability or versatility
If multiple test cocks are provided in the backflow preventer assembly, then the testing flexibility is improved, but the device complexity and robustness worsen
Solution Approach 1:
The patent extracts the testing functionality into a single dedicated test cock that can be sequentially connected to different measurement points. This extraction eliminates the need for multiple permanent test cocks built into the assembly, reducing structural complexity while maintaining testing flexibility.
4Measurement precision
If a complex testing method with specific attachment orders is used, then the measurement accuracy is improved, but the loss of time increases due to user error and repetition
Solution Approach 1:
The patent establishes a clear preliminary procedure: close isolation valves to isolate the section being tested, connect the test cock to the appropriate port, take the measurement, then move to the next port. This preliminary structuring of the testing sequence prevents user error and reduces time loss from incorrect operations.
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
The method allows for effective testing of backflow preventer assemblies using a simpler, cost-effective approach with a manometer, reducing the risk of user error and providing a more robust construction by minimizing the number of test cocks required.
Implementation Method 1
the relief valve is exposed to the pressure of the drinking water system in closing direction
Implementation Method 2
which is adapted to connect the space between the backflow preventers to a drain, when this pressure ceases
Implementation Method 3
measuring a hydrostatic pressure head with a pressure measurement device
Data Source
Figure 1
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Figure 3
AI summary
Method of testing a backflow preventer assembly (1), the backflow preventer assembly (1) comprising at least a backflow preventer (2), an upstream test cock (16) positioned upstream of an upstream check valve assembly (6), a downstream test cock (19) positioned downstream of a downstream check valve assembly (8), wherein both test cocks (16, 19) are configured to be attached to a liquid pressure measurement device (17), an upstream shut off valve (21) positioned upstream of the upstream test cock (16), wherein an upstream zone (18) is defined between the upstream check valve assembly (6) and the upstream shut off valve (21), a downstream shut off valve (22) positioned downstream of the downstream test cock (19), wherein a downstream zone (20) is defined between the downstream check valve assembly (8) and the downstream shut off valve (22). The method of testing the backflow preventer assembly (1) comprises testing the downstream shut off valve (22) and the downstream check valve assembly (8) by measuring a first pressure (23) development over time in the downstream zone (20) at the downstream test cock (19). It furthermore comprises testing an opening pressure (24) of a relief valve (13) by closing the upstream shut off valve (21), gradually lowering the pressure in the upstream zone (18) by tapping off liquid from the upstream zone (18) via the upstream test cock (16) and by measuring a second absolute pressure (25) at the upstream test cock (16) at which fluid starts to discharge via a discharge opening (11) and comparing said absolute pressure (25) to a required threshold pressure for the relief valve (13).