IMMERSION MEASURING PROBE FOR MEASUREMENTS IN FLUID METALS

Abstract: The measuring head mainly consists of a metal tube, surrounded over the major part of its length by a sheathing of fire-proof, respectively heat-resistant material, attached to the tube, the outer surface of said sheathing being tapered towards the tube end to be dipped first, which is shut off by a plug of fire-proof material carrying one or several measuring elements, the other end of the measuring head, respectively of the metal tube, being slid into one end of a tube of cardboard or similar material.

Description: "Immersion measuring probe for measurements in fluid metals". The present invention covers an immersion measuring probe for measurements in fluid metals. For measurement of e.g. temperature and/or oxygen content in a fluid metal, immersion probes are mostly used, which traditionally consist of a tube whose end to be dipped in first is shut off by a plug-shaped measuring head of fireproof material, carrying one or several measuring elements as well as a corresponding connector. The measuring elements protrude from the dipping side of the measuring head and the connector from the other side. For use, a measuring probe of this type is slid over a metal supporting lance, so that the connector contacts a contact block fitted in the lance for this purpose. This contact block is connected to a measuring instrument by electric conductors passing through the lance. The protruding portions of the measuring elements are usually protected by cardboard and/or metal caps fitted on the measuring head, which decpmpose, respectively melt down when dipped in the fluid metal. The aforementioned tubes are mostly made of cardboard. Such tubes are often provided with an insulating protective sheathing to prevent splashing and vibration when immersed. Immersion measuring probes of the type outlined above are described for example in Belgian patents No. 828.752, No. 881.886, No. 884.405 and No. 889.276 in the Applicant's name. An aim at still more accurate measuring and economy has induced the Applicant to develop a new generation of immersion measuring probes. Directions were set as follows a) a considerable reduction of the mass in the vicinity of the measuring elements to diminish their cooling effect on the metal and thus enabling more accurate measuring; b) if the probe comprises a thermo-couple, reduction of a temperature difference between its cold joints during immersion, respectively during measurement; c) if the probe comprises an electro-chemical cell, minimizing the probe's own influence on the oxygen concentration to be measured and the chemical balances related thereto; d) for economical reasons, elimination of the afore mentioned insulating protection of the cardboard tube. e) the complete protection of aforesaid connector. These objectives are met according to the invention by the measuring head consisting mainly of a metal tube, surrounded over the major part of its length by a sheathing of fireproof, respectively heat-resistant material, attached to the tube, the outer surface of this sheathing being tapered towards the metal tube end to be dipped in first, which is shut off by a plug of fireproof material carrying one or several measuring elements, while the other end of the measuring head, respectively the metal tube, is slid into one end of a tube made of cardboard or similar material. For better explana,tion an embodiment of the invention is described in detail below, with reference to the attached drawing showing an axial section of a measuring probe. The measuring probe shown mainly consists of a metal tube 1, surrounded over the major part of its length by a sheathing 2 fastened to tube 1 and made of moulding sand for example. The outer surface of sheathing 2 is tapered towards the end 3 of tube 1 to be dipped first. This end 3 is sealed by a plug 4 of fireproof cement carrying one or several measuring elements, in this case a thermo-couple 5 partly fitted in a quarz tube and an electrochemical cell 6. The cold joints 7 of thermo-couple 5 are embedded in a gastight filling such as silicone 8, surrounded by a small plastic casing 9 with a cloverleaf-shaped cross section. Tube 1 is filled with resin-impregnated but gas-permeable moulding sand 10, containing the open end of the electrochemical cell and through which pass conductors 11 and 12 to a connector 13 shutting off the other end 14 of tube 1. Tube 1 is used as a guide to contact the molten metal, e.g. for closing the circuit of the electro-chemical cell 6. An intrinsically known slag cap 15 is provided. A cardboard tube 16 is slid around end 14 of tube 1 until it contacts sheathing 2. Dimensions of sheathing 2 are by way of example - but also in preference - the following : length : lo cm; smallest external diameter (end 3) : 2.5 cm; largest external diameter 3.7 to 4.8 cm; internal diameter : 1.8 cm. The advantages of such a construction are obvious - extremely small mass of materials in the vicinity of the measuring elements; - exceptional protection of cold joints against mutual temperature differences; - favourable shape as regards penetration into the metal; - complete protection of the connector as well as of the supporting lance, even in case of breakage of sheating 2; - fairly simple, cheap and none the less sturdy con struction. Needless to say that several alternative embodiments can be contrived without exceeding the scope of the invention.

Claims: Claims. 1.- Immersion measuring probe for measurements in fluid metals, of the type consisting of a tube (1) whose end (3) to be dipped first is shut off by a plug-shaped measuring head carrying one or several measuring elements (5-6) as well as a corresponding connector (13), the said tube (1) being meant to be slid over the end of a hollow supporting lance, featuring that the measuring head (4) mainly consists of a metal tube (1), surrounded over the major part of its length by a sheathing of fireproof, respectively heat-resistant material, attached to the tube (1), the outer surface of said sheathing (2) being tapered towards the metal tube end (3) to be dipped first, which is shut off by a plug of fireproof material carrying one or several measuring elements, the other end of the measuring head, respectively of the metal tube (1), being slid into the end of a tube (16) made of cardboard or similar material. 2.- Immersion measuring probe according to claim 1, featuring that the metal tube (1) is filled with resin-impregnated but gas-permeable mould sand (10), through which extend one or several conductors (11-12) from the said measuring element to the other end of the metal tube (1) which is shut off by a connector (13). 3.-, Immersion measuring probe according to claim 2, wherein a measuring element is a thermo-couple (5), featuring that the cold joints (7) of the thermo-couple (5) are embedded in a gastight filling such as silicone (8) which, in turn, is embedded in moulding sand. 4.- Immersion measuring probe according to claim 2 or 3, wherein a measuring element is an electro-chemical cell (6) with one open end, featuring that this open end extends into the aforementioned gas-permeable filling. 5.- Immersion measuring probe according to claim 1, fea turing that the said metal tube (1) is used as conductor, respectively for contacting the fluid metal.

Inventors: BOLLEN, THEO PIETER CLEMENT, CURE, OMER
Applicants: ELECTRO-NITE INTERNATIONAL N.V.
Application year: 1983
Main classification: G01K1
IPC codes: G01N27, G01K7, G01F23, G01N33, G01K1