Cable Entry Gland With Rotating Sleeve For Hazardous Atmosphere Sealing
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Solution Overview
Problem
Existing cable entry glands for hazardous environments, such as explosive atmospheres, require correct installation sequences to maintain sealing integrity, where the connecting sleeve must be fastened to the protective conduit before the gland is tightened, otherwise, incorrect installation can lead to loss of explosion protection and compromised sealing.
Innovation Solution
A gland design featuring a tubular connecting sleeve with a force-fitting connecting bore on the annular nut, allowing the sleeve to rotate freely and remain captive, enabling assembly under tension without compromising the seal, and incorporating a relief surface and ring seal for controlled rotation and increased friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the connecting sleeve is fastened to the protective conduit before tightening the gland, then the sealing integrity is maintained, but the installation sequence becomes complex and error-prone
Solution Approach 1:
The connecting sleeve is divided into two functional parts: a threaded portion for engaging the protective conduit and a cylindrical portion for force-fitting onto the annular nut. This segmentation allows each part to perform its function independently, enabling the sleeve to be installed on the conduit first without affecting the sealing mechanism.
Solution Approach 2:
The connecting sleeve is designed to be freely rotatable on the annular nut during installation, transforming from a static constrained component to a dynamic flexible one. This rotational freedom allows the sleeve to be screwed onto the conduit while the gland is already tightened, eliminating the complex installation sequence.
2Ease of operation
If the connecting sleeve is allowed to rotate freely on the annular nut, then assembly under tension is enabled, but the sleeve may become loose or misaligned
Solution Approach 1:
The cylindrical portion of the connecting sleeve is pre-designed with a force-fit interface that engages with the annular nut. This preliminary design ensures that once the sleeve is rotated into position during assembly, it automatically locks securely without requiring additional fastening actions.
Solution Approach 2:
Different portions of the connecting sleeve have different properties: the threaded portion provides secure engagement with the conduit, while the cylindrical portion provides free rotation and captive retention on the nut. This local differentiation of functional qualities enables both rotational freedom and positional stability.
3Adaptability or versatility
If the connecting sleeve is force-fitted onto the annular nut, then the sleeve remains captive and rotatable, but manufacturing precision requirements increase
Solution Approach 1:
The force-fit connection between the connecting sleeve and annular nut is designed as a separate, independent interface distinct from the threaded connections. This extraction of the retention function into a dedicated force-fit interface allows for standardized tolerance zones that are easier to manufacture while maintaining the desired captive rotatable behavior.
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
Enables flexible assembly configurations, ensuring the gland remains sealed and securely connected to the protective conduit, preventing incorrect installation issues that could compromise explosion protection.
Implementation Method 1
the outer surface of the end portion of the nut having a relief surface arranged so as to engage in the annular groove when the connecting bore is force-fitted on to the end portion, the engagement of the relief surface in the annular groove thus retaining the sleeve on the end portion of the nut and allowing the sleeve to rotate freely
Implementation Method 2
the tubular body contains a compressible sealing ring, an annular nut adapted to be screwed on to a tapped end of the tubular body opposite to the threaded end to compress the sealing ring
Data Source
AI summary
A gland (1) for an electrical cable inside a threaded protective conduit, the gland includes a tubular body (2) enclosing a sealing ring (3), an annular nut (4) screwed on to the body to compress the sealing ring, a tubular connecting sleeve connected to the nut, an end portion of the nut (4) opposed to the body (5) having a threaded part (51) for connection to the threaded conduit, the sleeve having a connecting bore (52) mounted by force-fitting on an outer surface (42) of the end portion of the nut, the connecting sleeve having an annular groove (54) on an inner surface (53) of the connecting bore; the outer surface of the nut (4) having a relief surface (43) which engages in the groove (54) during the force-fitting, so as to retain the sleeve on the end portion of the nut while allowing the sleeve to rotate freely around the nut.