Isokinetic Probe Assembly for Fluid Sampling
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Solution Overview
Problem
Existing probe assemblies for sampling fluids from pipelines suffer from dead-legs, which prevent isokinetic flow, impeding representative sampling as recommended by API Section 8.2, as the linear velocity of the fluid entering the sampling probe is not equal to that of the undisturbed fluid stream.
Innovation Solution
A probe assembly design featuring a chamfered or beveled outer tubular probe tip and return tube, positioned at the center of the pipeline, creating a venturi effect to ensure isokinetic flow, with a machined connection head and welded construction to maintain flow integrity and eliminate dead-legs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single probe design is used for sampling, then the device complexity is reduced, but isokinetic flow cannot be achieved and dead-legs are created
Solution Approach 1:
The probe is divided into multiple functional segments: an outer probe body and an inner return tube, each serving distinct purposes. The outer probe samples fluid while the inner return tube eliminates dead-legs by providing a separate return path, allowing isokinetic flow to be achieved without excessive complexity
Solution Approach 2:
The inner return tube is nested within the outer probe body, with the return tube positioned concentrically inside the sampling tube. This nested configuration allows the return flow to travel through the center while the sampling occurs in the annular space, eliminating dead-legs while maintaining compact design
2Ease of operation
If the probe is positioned away from the pipeline center, then installation is easier, but isokinetic flow condition is not met
Solution Approach 1:
The probe incorporates a localized chamfered or beveled opening at the sampling end, creating a specific flow condition zone at the probe entrance. This local geometric feature ensures isokinetic flow by matching the velocity profile at the sampling point, while the overall probe positioning can be optimized for installation ease
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 design ensures isokinetic flow, eliminating dead-legs and allowing for representative sampling by maintaining equal fluid velocity through the probe, enhancing the accuracy of fluid sampling and analysis.
Implementation Method 1
the outer opening has a chamfered or beveled circumference designed and configured to introduce isokinetic flow through the outer tubular probe tip
Data Source
AI summary
A probe assembly for providing a flow of a fluid from a pipeline into a sample transport line or slipstream, comprising: an outer tubular probe tip attached to a distal end of an outer tube mid-section; wherein the outer tubular probe tip has an outer opening; a connection head having an outer tube attached to a proximal end of an outer tube mid-section; wherein the outer tubular probe tip, the outer tube mid-section, and the outer tube are of a first inner diameter; wherein the outer opening of the outer tubular probe tip receives a flow of the fluid from within the pipeline that travels through the outer probe tip, the outer tube mid-section, the outer tube and connection head into the sample transport line or slipstream; a return tube, having an outer diameter smaller than the first inner diameter, disposed through the center of each of the outer tubular probe tip, the outer tube mid-section, the outer tube and the connection head; a first connection fitting for connecting return tubing to connection head; and a second connection fitting for connecting return tubing to the sample transport line or slipstream.