Flow tube for a magnetic flowmeter
First Claim
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1. A magnetic flowmeter comprising a flow tube formed of a low permeability, non-conductive ceramic material;
- the flowmeter having means externally disposed on the flow tube for producing a magnetic field in an electrically conductive pressurized fluid flowing through a bore in the flow tube and having circuit means external to the flow tube for receiving a signal representative of flow;
the flow tube having a wall surrounding the bore, the flow tube further comprising;
a plurality of regions having enhanced electrical conductivity formed in the ceramic material of the flow tube and having each region disposed in the wall between the bore of the flow tube and the circuit means for transferring the signal representative of flow from the electrically conductive fluid to the circuit means, the regions comprising ceramic mixtures of ceramic and metal powders sintered into the flow tube, the ceramic powder in the regions being constituted as substantially the same ceramic material as the flow tube to provide sufficient strength such that the wall contains the pressure and is substantially free from external support for containing the pressure.
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Abstract
A flow tube of a ceramic material used for a magnetic flowmeter is formed to have regions of a ceramic material which has enhanced properties useful in magnetic flowmeters, such as enhanced electrical conductivity or enhanced magnetic permeability. The ceramic material having enhanced electrical conductivity is used to form sensing surfaces directly in the flow tube wall so that there is no need to have separate metal electrodes attached to or otherwise formed in the wall of the flow tube. This insures a strong, monolithic flow tube wall.
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Citations
29 Claims
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1. A magnetic flowmeter comprising a flow tube formed of a low permeability, non-conductive ceramic material;
- the flowmeter having means externally disposed on the flow tube for producing a magnetic field in an electrically conductive pressurized fluid flowing through a bore in the flow tube and having circuit means external to the flow tube for receiving a signal representative of flow;
the flow tube having a wall surrounding the bore, the flow tube further comprising;a plurality of regions having enhanced electrical conductivity formed in the ceramic material of the flow tube and having each region disposed in the wall between the bore of the flow tube and the circuit means for transferring the signal representative of flow from the electrically conductive fluid to the circuit means, the regions comprising ceramic mixtures of ceramic and metal powders sintered into the flow tube, the ceramic powder in the regions being constituted as substantially the same ceramic material as the flow tube to provide sufficient strength such that the wall contains the pressure and is substantially free from external support for containing the pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- the flowmeter having means externally disposed on the flow tube for producing a magnetic field in an electrically conductive pressurized fluid flowing through a bore in the flow tube and having circuit means external to the flow tube for receiving a signal representative of flow;
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15. A flow tube formed of a low permeability, non-conductive ceramic material for a magnetic flowmeter;
- the flowmeter having means externally disposed on the flow tube for producing a magnetic field in an electrically conductive fluid flowing through a bore in the flow tube and having circuit means external to the flow tube for receiving a signal representative of flow;
the flow tube comprising;a first region formed of a ceramic material having enhanced magnetic permeability sintered in the ceramic material of the flow tube and disposed between the means for producing and the bore of the flow tube for transferring the magnetic field from the means for producing to the electrically conductive fluid flowing in the bore in the flow tube, and a second region formed of a ceramic material having enhanced electrical conductivity sintered in the ceramic material of the flow tube and disposed between the circuit means and the bore of the flow tube for transferring the signal representative of flow from the fluid to the circuit means and having mechanical strength such that the flow tube is pressure bearing. - View Dependent Claims (16, 17, 18, 19, 20, 21)
- the flowmeter having means externally disposed on the flow tube for producing a magnetic field in an electrically conductive fluid flowing through a bore in the flow tube and having circuit means external to the flow tube for receiving a signal representative of flow;
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22. An electromagnetic flowmeter for measuring a flow of a conductive fluid comprising:
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means for producing a magnetic field inducing a signal representative of flow in the conductive fluid; means for converting the signal representative of flow to an output signal; a flow tube having a cylindrical wall formed of a ceramic low permeability, non-conductive material for carrying the flow; a pair of ceramic electrode regions coupled to the converting means and formed of sintered powders disposed in the flow tube wall for sensing the induced signal; a pair of magnetic pole regions formed of a magnetic ceramic material and disposed in the flow tube wall for transferring the magnetic field from the means for producing to the conductive fluid; and wherein the pair of ceramic electrode regions and the pair of ceramic magnetic pole regions are sintered in such that the cylindrical wall is pressure bearing. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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29. A magnetic flowmeter comprising a flow tube formed of a low permeability, non-conductive ceramic material;
- the flowmeter having means externally disposed on the flow tube for producing a magnetic field in an electrically conductive pressurized fluid flowing through a bore in the flow tube and having circuit means external to the flow tube for receiving a signal representative of flow;
the flow tube having a wall surrounding the bore, the flow tube further comprising;a plurality of regions having enhanced electrical conductivity formed in the ceramic material of the flow tube and having each region disposed in the wall between the bore of the flow tube and the circuit means for transferring the signal representative of flow from the electrically conductive fluid to the circuit means, the regions comprising ceramic mixtures of ceramic and metal powders sintered into the flow tube to provide sufficient strength such that the wall contains the pressure and is substantially free from external support for containing the pressure, the mixture of ceramic and metal powders in the regions being gradually varied in the regions such that stress concentration is reduced.
- the flowmeter having means externally disposed on the flow tube for producing a magnetic field in an electrically conductive pressurized fluid flowing through a bore in the flow tube and having circuit means external to the flow tube for receiving a signal representative of flow;
Specification