Pneumatic Test Gun Self-Actuating Retaining Elements
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hand-held pneumatic tube test guns can unintentionally slip out of pressurized tubes, leading to sudden decompression and safety risks, and require increased operator force and additional valves to maintain friction and prevent leaks.
Innovation Solution
A pneumatic test gun with a longitudinally-compressible and radially-expandable annular seal and a self-activating retaining element assembly that expands into engagement with the tube's inner diameter to secure the gun in place without deforming the tube, using compressed air to activate the seal and retaining elements for improved retention and reduced operator effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional test gun relies on friction between the seal and tube inner diameter for retention, then the device structure remains simple, but the gun can unintentionally slip out of pressurized tubes causing safety risks
Solution Approach 1:
The retaining element is divided into multiple radially-spaced teeth that independently engage with the tube inner diameter, distributing the retention force and improving overall grip reliability without requiring excessive friction from a single seal surface
Solution Approach 2:
The retaining element acts as an intermediary mechanical feature between the test gun and tube, providing positive engagement through teeth that bite into the tube ID, thereby eliminating reliance solely on friction-based seal retention
2Reliability
If the friction force between seal and tube is increased to prevent slippage, then retention improves, but the operator must exert greater pushing force throughout the test duration
Solution Approach 1:
The retaining element is self-actuating through compressed air pressure that forces it radially outward to engage the tube ID, eliminating the need for operator force to maintain retention during the test
Solution Approach 2:
Compressed air pressure is utilized to actuate the retaining element radially outward into engagement with the tube, converting the test medium itself into the actuating force for retention, thereby reducing operator effort
3Reliability
If a larger actuation piston is used to increase friction force, then seal engagement improves, but the device complexity and valve requirements increase
Solution Approach 1:
The compressed air serves multiple functions: pressurizing the tube for testing, expanding the seal for sealing engagement, and actuating the retaining element for positional retention, eliminating the need for separate actuators and valves
Solution Approach 2:
The seal actuation and retention actuation systems are merged into a single compressed air-driven mechanism, where the same air pressure that expands the seal also forces the retaining element outward, simplifying the overall device architecture
4Reliability
If radial expansion force is increased to improve retention, then the gun holds better in the tube, but the tube inner surface may be deformed or damaged
Solution Approach 1:
The retaining element teeth are designed with specific geometric features including rounded tips and optimized spacing to concentrate engagement forces at discrete points rather than distributing them continuously, reducing overall contact stress on the tube inner surface
Solution Approach 2:
The material properties and geometric parameters of the retaining element teeth are optimized to provide sufficient engagement force for retention while maintaining contact stresses below the tube material's yield threshold, preventing deformation
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
Enhances operator safety by preventing accidental slippage and reducing the force required to hold the gun during testing, allowing for higher test pressures and use in wet conditions without damaging the tube, while simplifying the setup process.
Implementation Method 1
a longitudinally-compressible and radially-expandable annular seal located on the support tube that expands into sealing engagement with an inner diameter of the tube to be tested when air is injected into the tube to be tested
Implementation Method 2
a self-activating retaining element assembly adapted to be radially-expandable into engagement with an inner diameter of a tube to be tested to improve retention of the distal end portion within the tube to be tested
Implementation Method 3
using compressed air to activate the seal and retaining elements for improved retention
Data Source
AI summary
A pneumatic test gun for use in performing a leak test on a tube is provided. The pneumatic test gun has a handle for being manually gripped by an operator, a distal end portion for insertion into a tube to be tested, and a proximal end plate from which the distal end portion extends and which is adapted to be abutted against an open end of the tube to be tested. The distal end portion includes a support tube providing a flow path for compressed air into a tube to be tested, a longitudinally-compressible and radially-expandable annular seal located on the support tube, and a self-activating retaining element assembly adapted for radial-expansion into engagement with an inner diameter of the tube to be tested to improve retention of the distal end portion within the tube when the tube is pressurized during a leak test. A method is also provided.