Explosion-Proof Measuring Cell With Variable Gap Sealing
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Solution Overview
Problem
Existing measuring cells with pressure transducers face manufacturing difficulties due to tight and lengthy gap requirements for explosion-proof enclosures, which increase production costs and complexity, especially in ensuring gap sizes comply with standards for ignition-flashover resistance and pressure equalization.
Innovation Solution
A measuring cell with a casing featuring a pressure compensation vent and a sealing element with an axisymmetrical circumferential surface, where a strip-shaped plane surface section interacts with the internal casing bore to form a gap resistant to ignition flashovers, allowing for adjustable gap widths and cost-effective production, using materials like polyphenyline sulfide (PPS) for the sealing element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tight and lengthy gaps are used in explosion-proof enclosures to prevent ignition flashovers, then explosion safety is improved, but manufacturing complexity and production costs increase
Solution Approach 1:
The patent changes the geometric parameters of the gap by introducing a stream-splitting device that creates a non-uniform gap profile. The gap width varies along its length, being narrower at certain sections and wider at others, which allows the same gap to provide both ignition protection and reduced manufacturing complexity. This parameter optimization resolves the contradiction by showing that uniform tight gaps are not necessary - varied gap dimensions achieve the same safety effect with easier manufacturing.
Solution Approach 2:
The gap is segmented into different functional zones by the stream-splitting device. One section of the gap provides primary ignition protection while another section facilitates pressure equalization. This segmentation allows each zone to be optimized independently - the ignition-resistant zone can be tighter while the pressure equalization zone can be wider and easier to manufacture, thus resolving the overall contradiction.
2Reliability
If capillary tubes with precise dimensions are used for pressure equalization in glass seals, then pressure compensation is improved, but production costs and production losses increase
Solution Approach 1:
The patent extracts the pressure equalization function from the complex glass seal assembly with capillary tubes and relocates it to a separate, simpler plastic component. The pressure equalization hole is formed directly in the plastic sealing element using injection molding, eliminating the need for separate capillary tubes and complex glass sealing procedures. This extraction resolves the contradiction by separating the pressure equalization function from the ignition protection function, allowing each to be optimized independently for cost and manufacturability.
Solution Approach 2:
The patent replaces the mechanical assembly of glass seals with capillary tubes with a monolithic plastic sealing element. The pressure equalization hole is formed directly in the plastic material during injection molding, substituting the complex mechanical assembly process with a single molding operation. This substitution eliminates the need for precise mechanical tolerances in multiple components and significantly reduces production complexity and cost while maintaining pressure compensation functionality.
3Reliability
If strict sealing requirements are imposed to prevent explosion propagation, then explosion protection is improved, but manufacturing precision requirements and production losses increase
Solution Approach 1:
The patent uses composite sealing construction combining plastic material with integrated sealing features. The plastic sealing element incorporates both ignition protection and pressure equalization functions within a single monolithic component. This composite approach allows the sealing element to achieve both explosion protection and pressure compensation without requiring multiple precision-machined components, thus reducing overall manufacturing precision requirements while maintaining reliability.
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 solution enables a compact, cost-effective measuring cell that meets explosion-proof standards with reduced production complexity and lower costs, ensuring effective ignition-flashover resistance and pressure compensation while maintaining leak tightness and high bonding quality.
Implementation Method 1
the dimensions must be so tight and of a great length so that a flame of an explosion is extinguished and the temperature of the explosion gases is reduced sufficiently by cooling, so that no ignition can occur in the surrounding atmosphere
Implementation Method 2
a capillary tube with an inside bore of 0.2 mm and a length of 17 mm was used for pressure equalization
Data Source
AI summary
The invention relates to a measuring cell with a casing for housing a sensor, in particular a pressure transducer, in which the casing has a pressure compensation vent for the sensor; and is provided with a sealing element with an axisymmetrical circumferential surface arranged proximate an internal surface of a casing bore formed operably and complementary hereto, and that the pressure compensation vent is formed as at least one gap resistant to ignition flashovers by interaction of a strip-shaped and plane surface section extending along the casing bore on the circumferential surface of the sealing element with the internal surface of the casing bore.