Leco Corporation

Larry S O'Brien

Peter Markel Willis

Gordon C Ford

Ward S Kaler

Robert S Tate

Roger L Bredeweg

Charles B Vallance

Keith J Adani

Robert G Warren

William R Strunk

Ronald A Klemm

The analyzer of the present invention is specifically adapted to provide moisture determinations for foods and other agricultural material. It allows the operator to introduce a precise weight of sample into a crucible in a closed furnace in a controlled environment through an access port in the furnace cover. The access port in the cover can be tapered to allow easy access to an underlying aligned crucible and allow an operator to add and remove sample material from the crucible until a precise desired sample weight is reached as measured by a balance within the furnace. The access port is enclosed by an insulated cover after the samples are sequentially placed in the crucibles.

Access port for a thermogravimetric analyzer furnace

An electrical resistance heated oven is used to heat a crucible to melt a sample and to simultaneously heat a casting dish into which the molten sample can be poured. The oven is cooled with the crucible and casting dish within the oven in order to prepare a sample bead for analysis. In another embodiment of the invention the sample is again melted in a crucible and after melting the crucible is moved out of the oven and turned to pour the molten sample into an acid solution positioned external to the oven. The crucible and sample can be moved while in the oven to mix the sample. The method of preparing an analytical sample using the electrical resistance heated oven is also disclosed.

Resistively heated sample preparation apparatus

An interchangeable module for supporting a receptacle into which a molten sample, prepared by a fluxer, can be poured for analysis. One module can support a resistively heated casting dish into which a molten sample can be poured and cooled to form a solid sample for instrumental analysis. This module includes an insulator having a depression for receipt of a casting dish. A heating coil is positioned below the recession. A cooling gas conduit extends through the insulator support. The insulator is supported on a frame. The frame is supported on a back plate.

Analytical sample preparation system

A combustion chamber includes an inner cylindrical member concentrically mounted within an outer cylindrical member with a cylindrical space therebetween. The outer cylindrical member is enclosed at one end and both cylindrical members are open at an opposite end for access to the combustion area. The by-products of combustion are withdrawn from the inner cylindrical member at the closed end of the outer cylindrical member such that they reverse direction and circulate through the hot zone of the furnace in the cylindrical space. In a preferred embodiment of the invention, a porous ceramic plug which supports and spaces the tubes in concentric relationship at the one end and captures particulate by-products of the combustion holding them in the hot zone for complete combustion.

Combustion system

The specification discloses a window assembly for an analytical furnace enabling the window to be readily and easily removed and reinstalled to facilitate servicing of the window. The assembly includes a one-piece fused silica housing having concentric inner and outer tube portions. The outer tube portion defines a transverse slot through which a window is inserted to overlie an end of the inner tube. A spring is included to bias the window into engagement with the inner tube to reduce airflow and heat loss therebetween.

Analytical furnace window assembly

An ash fusion analyzer for determining the ASTM defined fusion temperatures of coal and coke ash includes a furnace chamber with a viewport. A rotatable sample-supporting platform is positioned within the chamber such that samples on the platform are viewable through the viewport. An optical system is aligned with the viewport for directing images of the moving samples onto a solid state line scan array. A microprocessor is coupled to the array for periodically sampling data from the array and calculating shape information relating to the samples.

Ash fusion system

The specification discloses an analyzer having a furnace defining a furnace chamber and including a floor with an aperture communicating with the chamber. A sample-supporting platform is provided and movable between an analyzing position within said furnace chamber and a loading position below the level of, and out from under, the furnace. A plurality of heating elements extend into the furnace chamber and are insulatively sealed therein by a pair of slotted members which cooperate to reduce airflow along the elements.

Analytical furnace

A combustion system includes a cylindrical horizontally extending ceramic combustion tube enclosed at one end and open at the opposite end for receiving a combustion boat carrying a sample to be combusted for subsequent analysis. An externally mounted sample eduction tube is coupled at one end to the interior space near the enclosed end of the combustion tube and secured at its opposite end to the combustion tube by means of a slide assembly to accommodate for differential movement between the combustion tube and the eduction tube. A lance tube also extends into the combustion tube for directing the flow of an oxidizing gas into the combustion boat to facilitate oxidation of a sample. The open end of the combustion tube is effectively sealed by a curtain of gas supplied by a flood tube for blocking the open end of the tube from admission of atmospheric contaminants and preventing the escape of gases from the combusted sample. A baffle structure is positioned between the combustion boat and gas exit to contain volatile samples during combustion.

A combustion system includes a cylindrical horizontally extending ceramic combustion tube positioned in a furnace. The combustion tube is enclosed at one end and open at the opposite end for receiving a combustion boat carrying a sample to be combusted for subsequent analysis. The tube also receives a support block loosely positioned along the bottom of the tube and contacting the enclosed end for centering the combustion boat and for supporting one end of a sample withdrawal tube with an open end extending in the space surrounding the combustion boat and having an opposite end extending from the combustion tube. A lance tube also extends into the combustion tube for directing the flow of an oxidizing gas such as oxygen into the combustion boat to facilitate oxidation of a sample. The open end of the combustion tube is effectively sealed by a curtain of gas supplied by a flood tube having a plurality of longitudinally and angularly spaced slots and supplied with a suitable gas for blocking the open end of the tube from admission of atmospheric contaminants and preventing the escape of gasses from the combusted sample.

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St. Joseph, MI, United States of America

Larry S O'Brien