Flow Cell Screw Thread Sealing for Dissolution Testing

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Solution Overview

Problem

Existing flow cells in dissolution test devices face issues with sealing, leading to leaks between the water circuit and the test medium circuit, causing contamination, loss of dissolved active substances, and irreproducible measurements due to inaccuracies in part alignment and handling errors.

Innovation Solution

The flow cell design replaces traditional O-ring seals and external clamping devices with a screw thread connection between the cylindrical cell jacket and cell holder, incorporating a flat seal for improved sealing and easier cleaning, allowing for precise guidance and reduced susceptibility to handling errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional O-ring seals and external clamping devices are used, then the flow cell can be easily assembled and disassembled, but sealing reliability deteriorates due to leaks between water circuit and test medium circuit

Engineering Contradiction:
ImproveAssembly and disassembly easeVSAvoidSealing reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The flow cell is divided into separate modular components (cell body, filter head, sample cell) that can be independently assembled and disassembled. Each component has standardized connection interfaces with integrated sealing surfaces, allowing easy assembly while maintaining reliable sealing through precise mechanical fit rather than relying on deformable O-rings.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Flat seals are introduced as intermediary sealing elements between the modular components. These flat seals provide a reliable barrier between the water circuit and test medium circuit while being simpler and more reliable than traditional O-ring seals, eliminating the need for external clamping devices.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If toroidal O-ring seals are used for sealing, then the parts can be provisionally held during assembly, but measurement precision deteriorates due to leaks causing contamination and loss of dissolved active substances

Engineering Contradiction:
ImproveProvisional holding capabilityVSAvoidMeasurement reproducibility
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The design accepts that simple flat seals may need replacement over time, but they provide sufficient reliability for their service life. The seals are inexpensive and easy to replace, ensuring measurement precision is maintained throughout the operational period without the complexity of reusable O-ring systems.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Strength

If external clamping devices are used to press assembled parts, then the flow cell can be securely mounted, but device complexity increases and cleaning becomes more difficult

Engineering Contradiction:
ImproveMounting securityVSAvoidNumber of components
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The mounting security function is merged into the standardized connection interfaces between modular components. The interfaces themselves provide the necessary mechanical strength and sealing through their design, eliminating the need for separate external clamping devices and reducing overall system complexity.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If complex sealing mechanisms are used to prevent leaks, then sealing reliability improves, but ease of cleaning deteriorates due to more parts and crevices

Engineering Contradiction:
ImproveLeak preventionVSAvoidCleaning ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

Complex sealing mechanisms are extracted and replaced with simple flat seals and standardized interfaces. The design prioritizes cleanability by minimizing crevices and complex geometries, using only the essential sealing elements needed for leak prevention while maintaining ease of cleaning.

Inventive Principle:
Principle #2Taking out (Extraction)

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

This design enhances sealing reliability, prevents leakage, and simplifies the cleaning process, ensuring consistent and reproducible measurements by maintaining temperature control and flow guidance without deflection, thus reducing the risk of contamination and loss of test specimens.

Implementation Method 1

the test medium is pumped through the heating coil into the sample cell at a constant flow rate, where it dissolves the test item. On the one hand, it is tempered to the test temperature in the heating spiral

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

The flow cell design replaces traditional O-ring seals and external clamping devices with a screw thread connection between the cylindrical cell jacket and cell holder, incorporating a flat seal for improved sealing

Methodology Applied
Scientific EffectMechanical Fastening: Mechanical Fastener

Implementation Method 3

the cylindrical cell jacket is connected to the cell holder and the filter head by means of a screw thread. This allows the parts to be guided safely while at the same time being easy to dismantle

Methodology Applied
Scientific EffectScrew connection: Screw

Implementation Method 4

The top element of the sample cell in front of the outlet is always a filter that retains undissolved particles in the cell

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 5

the test medium is pumped through the heating coil into the sample cell at a constant flow rate, where it dissolves the test item

Methodology Applied
Scientific EffectDissolution: Solvation

Data Source

PatentEP3361230B1Flow cell for a dissolution test device
Publication Date: 2023.03.29 ERWEKA APPARATEBAU GMBH
  • EP3361230B1 patent drawingFigure 1
  • EP3361230B1 patent drawingFigure 2

AI summary

The present invention relates to a flow cell for a dissolution test device and a corresponding dissolution test device. To achieve improved sealing of the flow cell while simultaneously ensuring good cleanability and ease of use, the invention eliminates the need for conventional O-ring seals and an external clamping device for the inserted parts. Instead, the cylindrical cell shell is connected to the cell receptacle and the filter head by means of a screw thread. Sealing is achieved via flat end gaskets.