Closet Flange Knockout Design for Blockage Prevention
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Solution Overview
Problem
Existing closet flanges with integral test caps pose a risk of blockages in the plumbing system after pressure testing, as the test cap must be carefully removed to avoid passing through the flange and causing sewer blockages.
Innovation Solution
A closet flange design featuring a recessed knockout with a frangible connection and vertical uprights within the inlet opening, which supports protrusions to prevent accidental passage and facilitates safe removal by providing raised flat surfaces for striking, ensuring the knockout remains within the bore until intended.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an integral test cap is used for pressure testing, then pressure testing can be performed, but the test cap may accidentally pass through the flange and cause sewer blockages
Solution Approach 1:
The test cap function is segmented from the main flange body through a removable knockout design. The knockout is initially installed as part of the flange but can be separately removed after testing, allowing the testing function to be separated from the permanent flange structure. This prevents the permanent flange from being compromised while still providing temporary test access.
Solution Approach 2:
The knockout is extracted as a removable component from the flange body. It is initially embedded in the flange to provide pressure testing capability, but can be completely removed after testing completes. This extraction eliminates the risk of the test component remaining in the system and causing blockages, while maintaining the flange's integrity.
2Ease of operation
If the knockout is made easily removable, then pressure testing is enabled, but the knockout may be accidentally removed during installation
Solution Approach 1:
The knockout features localized friction engagement surfaces within the flange bore that provide sufficient resistance during normal handling and installation. The friction fit is strong enough to prevent accidental removal during rough handling or installation activities, yet can be deliberately broken out when intentionally removed with appropriate tools or force.
Solution Approach 2:
The knockout is preliminarily secured in the flange bore through a friction fit design that provides initial stability during installation and testing. This preliminary securing mechanism ensures the knockout remains in place during critical phases before deliberate removal is intended.
3Object-affected harmful factors
If the knockout is recessed in the flange, then accidental passage through the flange is prevented, but removal after testing becomes more difficult
Solution Approach 1:
The recessed knockout design serves multiple functions: it prevents accidental passage through the flange during installation, provides a friction fit for secure positioning, and maintains structural integrity of the flange. The same recessed configuration that prevents accidental removal also provides the friction engagement necessary for deliberate removal after testing.
Data Source
AI summary
A closet flange includes a body having a lower body portion containing a bore and an upper body portion containing an inlet opening in fluid communication with the bore. Within the body is a knockout for closing off the bore. The knockout has a frangible connection with an interior wall of the body and one or more portions that extend radially outwardly into a portion of the inlet opening that has a larger diameter than the bore to permit the knockout to be broken out of the body while preventing the knockout from passing all the way through the bore.