Redundant Level Measuring System with Coaxial Probe
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Solution Overview
Problem
Existing redundant level measuring systems face issues with float failure, leading to loss of both primary visual and secondary transmitter signals, and require larger chamber sizes to accommodate the float, probe, and shield, increasing costs.
Innovation Solution
A redundant level measuring system with a guided wave radar transmitter and a magnetic level indicator, where a coaxial probe with an inner rod and outer tube is used, minimizing chamber size by using a smaller diameter pipe and a float with a spherical outer wall to isolate the magnetic float from the probe, and incorporating a centering disk and end cap for precise alignment and drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic level indicator with a float and magnet is used, then local visual indication of level is provided, but the float may fail causing loss of both primary visual and secondary transmitter signals
Solution Approach 1:
The invention divides the level measurement function into two independent systems: a magnetic level indicator (visual indication) and a through-air radar transmitter (electronic signal). Each system operates independently without sharing common components, so that failure of one does not affect the other. The float contains magnets for the visual indicator while the radar probe uses electromagnetic waves for electronic measurement, creating independent measurement pathways.
Solution Approach 2:
The invention introduces an intermediary approach where the through-air radar probe measures level remotely through the chamber wall and process material without direct contact with the float or process media. This intermediary measurement method eliminates the single point of failure issue where float failure would affect both measurement systems, as the radar operates independently through electromagnetic wave transmission and reflection.
2Object-affected harmful factors
If an elongate shield is used to isolate the float from the probe, then magnetic interaction between float and probe is reduced, but the chamber size must be at least 4'' NPS increasing costs
Solution Approach 1:
The invention extracts the magnetic float from the radar measurement field by using a through-air radar design where the probe measures level through the chamber wall and process material without being affected by the float's magnetic field. The radar waveform transmission and reflection occur through non-magnetic media (air and process material), eliminating the need for magnetic shields and allowing use of smaller chambers.
Solution Approach 2:
The invention replaces the mechanical/magnetic interaction-based level measurement (float position detected by magnetic sensors or reed switches) with an electromagnetic wave-based measurement system (through-air radar). This substitution eliminates magnetic interference issues entirely, as the radar measures dielectric properties of the process material rather than detecting magnetic field positions, allowing smaller chamber dimensions.
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 system provides reliable redundant level measurement with reduced chamber size and cost, maintaining signal integrity by isolating magnetic interactions and ensuring the probe's centering within the chamber, thus minimizing the risk of float failure and reducing material costs.
Implementation Method 1
The float is sized and weighted for the specific gravity and pressure of the application and contain magnets which actuate a visual indicator on the outside of the chamber to indicate level
Implementation Method 2
A level measurement instrument includes a measurement circuit and a coaxial probe having an inner rod and a coaxial outer tube. The probe defines a transmission line and the coaxial outer tube has a through opening so that material level in the chamber equalizes with material level in the coaxial outer tube. The measurement circuit generates and receives a frequency signal on the transmission line, the measurement circuit measuring level of the material in the coaxial outer tube
Implementation Method 3
The coaxial outer tube has a through opening so that material level in the chamber equalizes with material level in the coaxial outer tube
Data Source
AI summary
A redundant level measuring system comprises comprising a chamber for fluidic coupling to a process vessel whereby material level in the vessel equalizes with material level in the chamber. A float including a magnet in the chamber interior space rises and falls with material level in the chamber. The float comprises an inner cylindrical wall defining an elongate through opening. A magnet actuated visual indicator is mounted to the chamber for indicating level of the magnet in the chamber. A level measurement instrument includes a measurement circuit and a coaxial probe having an inner rod and a coaxial outer tube. The probe defines a transmission line and the coaxial outer tube has a through opening so that material level in the chamber equalizes with material level in the coaxial outer tube. The instrument is mounted atop the chamber with the probe directed downwardly to the chamber interior space and extending through the float through opening. The measurement circuit generates and receives a frequency signal on the transmission line, the measurement circuit measuring level of the material in the coaxial outer tube.