GB2169079A - Electromagnetic flow meter - Google Patents

Abstract

An electrode clamp for an electromagnetic flow meter serves to mount the electrodes (14), (15) and an electromagnet (10, 12) in such a way that the electrodes can be clamped and unclamped from liquid metal conducting pipework (20), thereby avoiding the need to weld the electrodes in place. The clamp is designed as a portable unit so that it can be readily moved from one section of pipework to another and comprises a caliper arrangement (18) pivoted to pole pieces (12) and cable 24 operating the calipers. Electrode (14) is fixed and electrode (15) moveable with one of the caliper arms (18). <IMAGE>

Description

SPECIFICATION Electromagnetic flow meter This invention relates to electromagnetic flow meters for liquid metals and is particularly concerned with the location of electrodes and a magnetic source in relation to a metal conduit through which liquid metal flows.

In a known arrangement, the electrodes for picking up the emf generated by interaction between a magnetic field and the flowing metal are welded to the outer surface of the pipe and the magnetic field is provided either by a free-standing magnet with the conduit located between its poles or by a magnet supported by the pipe itself.

There are however situations where it is not practicable to weld the electrodes to the conduit, eg. when the conduit already contains flowing metal.

According to the present invention there is provided a clamping device unit for attachment to a conduit for an electrically conductive fluid, the clamping unit including electrode means for contact with the conduit and a magnetic source.

Thus, in accordance with the invention, the electrode means and the magnetic source may be automatically located in operative relation with the conduit as a result of engaging the unit with the conduit. With such an arrangement, it is unnecessary for the electrode means to be welded to the conduit since the electrode means may be engaged automatically with the conduit as a result of clamping the unit to the conduit.

The clamping action is conveniently effected by a caliper arrangement, the arms of which may be pivotally connected to structure forming part of the magnetic circuit associated with the magnetic source.

One embodiment of the invention will now be described by way of example only with reference to the accompanying drawing the sole Figure of which is a diagrammatic view showing, in solid outline, the clamping unit attached to a liquid metal conducting pipe and, in broken outline, the arrangement of the caiiper prior to attachment to the pipe.

As shown, the clamping unit comprises an electromagnet having an energising coil 10, wound with a cable capable of withstanding the environment in which it is to be used, mounted between two ferromagnetic steel pole pieces 12 by a ferromagentic steel bolt 3, the latter acting as part of the magnetic circuit.

Mounted on the electromagnet are the fixed electrode 14 and clamping calipers 18, the latter being pivoted at 19 to the pole pieces 12. The fixed electrode 14 is a stainless steel pin insulated from the magnet assembly and sufficiently robust to withstand the clamping forces when the calipers are tightened. One arm of the caliper system carries the movable electrode 15, insulated similarly to the fixed electrode, which contacts the pipe 20 opposite the fixed electrode 14 when the calipers are closed. The other arm of the calipers 18 contacts the pipe 20 directly to give additional support.

The calipers 18 are operated by means of a Bowden cable, its inner cable 22 attached to the magnet assembly and its sheath 24 to the main pivot 26 of the calipers. A lock nut arrangement at the end remote of the Bowden cable from the calipers ensures that the latter remains firmly clamped to the pipe 20 containing the flowing liquid. Signal cables 28 are attached to the fixed and movable electrodes 14, 15 and taken as a twisted pair to the potential measuring system (not shown).

From the foregoing, it will be seen that the unit may be readily clamped to the pipe at any selected position and subsequently releasing for use at another position. Moreover, it will be seen that the unit is portable and the action of clamping the calipers to the pipe automatically locates the electrodes and the magnetic pole pieces in the required relationship to the pipe.

1. A clamping unit for attachment to a conduit for an electrically conductive fluid, the clamping unit including electrode means for contact with the conduit and a magnetic source.

2. A unit as claimed in Claim 1 in which the clamping arrangement is operable to engage the electrode means automatically with the conduit in response to clamping the unit to the conduit.

3. A unit as claimed in Claim 1 or 2 in which the clamping action is effected by a caliper arrangement, the arms of which are pivotally connected to structure forming part of the magnetic circuit associated with the magnetic source.

4. A clamping unit as claimed in Claim 1, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electromagnetic flow meter This invention relates to electromagnetic flow meters for liquid metals and is particularly concerned with the location of electrodes and a magnetic source in relation to a metal conduit through which liquid metal flows. In a known arrangement, the electrodes for picking up the emf generated by interaction between a magnetic field and the flowing metal are welded to the outer surface of the pipe and the magnetic field is provided either by a free-standing magnet with the conduit located between its poles or by a magnet supported by the pipe itself. There are however situations where it is not practicable to weld the electrodes to the conduit, eg. when the conduit already contains flowing metal. According to the present invention there is provided a clamping device unit for attachment to a conduit for an electrically conductive fluid, the clamping unit including electrode means for contact with the conduit and a magnetic source. Thus, in accordance with the invention, the electrode means and the magnetic source may be automatically located in operative relation with the conduit as a result of engaging the unit with the conduit. With such an arrangement, it is unnecessary for the electrode means to be welded to the conduit since the electrode means may be engaged automatically with the conduit as a result of clamping the unit to the conduit. The clamping action is conveniently effected by a caliper arrangement, the arms of which may be pivotally connected to structure forming part of the magnetic circuit associated with the magnetic source. One embodiment of the invention will now be described by way of example only with reference to the accompanying drawing the sole Figure of which is a diagrammatic view showing, in solid outline, the clamping unit attached to a liquid metal conducting pipe and, in broken outline, the arrangement of the caiiper prior to attachment to the pipe. As shown, the clamping unit comprises an electromagnet having an energising coil 10, wound with a cable capable of withstanding the environment in which it is to be used, mounted between two ferromagnetic steel pole pieces 12 by a ferromagentic steel bolt 3, the latter acting as part of the magnetic circuit. Mounted on the electromagnet are the fixed electrode 14 and clamping calipers 18, the latter being pivoted at 19 to the pole pieces 12. The fixed electrode 14 is a stainless steel pin insulated from the magnet assembly and sufficiently robust to withstand the clamping forces when the calipers are tightened. One arm of the caliper system carries the movable electrode 15, insulated similarly to the fixed electrode, which contacts the pipe 20 opposite the fixed electrode 14 when the calipers are closed. The other arm of the calipers 18 contacts the pipe 20 directly to give additional support. The calipers 18 are operated by means of a Bowden cable, its inner cable 22 attached to the magnet assembly and its sheath 24 to the main pivot 26 of the calipers. A lock nut arrangement at the end remote of the Bowden cable from the calipers ensures that the latter remains firmly clamped to the pipe 20 containing the flowing liquid. Signal cables 28 are attached to the fixed and movable electrodes 14, 15 and taken as a twisted pair to the potential measuring system (not shown). From the foregoing, it will be seen that the unit may be readily clamped to the pipe at any selected position and subsequently releasing for use at another position. Moreover, it will be seen that the unit is portable and the action of clamping the calipers to the pipe automatically locates the electrodes and the magnetic pole pieces in the required relationship to the pipe. CLAIMS

1. A clamping unit for attachment to a conduit for an electrically conductive fluid, the clamping unit including electrode means for contact with the conduit and a magnetic source.

2. A unit as claimed in Claim 1 in which the clamping arrangement is operable to engage the electrode means automatically with the conduit in response to clamping the unit to the conduit.

3. A unit as claimed in Claim 1 or 2 in which the clamping action is effected by a caliper arrangement, the arms of which are pivotally connected to structure forming part of the magnetic circuit associated with the magnetic source.

4. A clamping unit as claimed in Claim 1, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.