Abstract: 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.

Abstract: The sampling tube of the present invention is cost effective in its design and operates efficiently and relatively quickly in order to obtain a complete hydrogen sample although its application is not necessarily limited to the sampling of hydrogen content of a molten specimen.A sampling tube includes a pair of concentric tubes with an inner tube projecting outwardly and having a fusible end cap at an extending end which, when submerged in a molten sample, admits the molten sample into the evacuated tube. The inner tube has a substantially uniform cross-sectional diameter to freely allow the molten sample to fill the inner tube and solidify as the tube is removed. Diffusible hydrogen flows from the inner tube into the outer tube through a flow-reversing cap and passageway at the opposite end of the inner tube.

Abstract: An electrode assembly includes an electrode and a crucible-supporting insert releasably secured to the electrode. In the preferred embodiment a collar is threaded onto the electrode and has tabs extending inwardly to clamp the insert to the electrode. A small button-like projection on the electrode may be provided and is received within an aperture in the insert to center the insert on the electrode.

Abstract: A control system for applying operating power to an analytical furnace includes a first circuit providing output signals consisting of a series of binary bits in a predetermined pattern with each bit corresponding to a unit of power to be applied to an analytical furnace according to the pattern of bits and a control circuit coupled to the first circuit and including output terminals for coupling the control circuit to an analytical furnace. The control circuit responds to the binary bits to provide pulses of operating power to the output terminals in a sequence corresponding to and controlled by the binary bits. The pattern of bits provides stepwise increasing temperature levels for the analytical furnace in a very predictable and controlled fashion such that samples combusted by the furnace will emit specimen gases associated with different compounds containing the specimen gas at different temperature levels.

Abstract: A calorimeter vessel includes a base for supporting a bomb thereon and a downwardly concavely opening container sealably engaging the base. The base includes a water supply system permitting a common water supply to supply water to three such vessels which include water level detecting sensors also permitting automatic filling of the vessels. In the preferred embodiment the vessel is filled in two stages providing rapid yet precise filling of each of the vessels. In one embodiment of the invention a microprocessor control circuit is employed for sampling temperature data within each of the vessels during an analysis to ascertain beginning and ending temperatures and for calculating the resultant heat of combustion of a sample. The microprocessor also is employed to automatically control the filling and emptying of the vessel and the firing of the sample containing calorimeter bomb.

Abstract: A sample loading mechanism includes a hopper mounted to a base for positioning the hopper with respect to a furnace for releasably holding a relatively small sample in relation to a crucible used with the furnace. The hopper includes a floor with a movable element for alternately closing the floor for holding the sample and opening the floor permitting the sample to drop into the crucible. A plate is slideably mounted to the base above the hopper and includes an aperture which aligns with the hopper in a first position for admitting a sample to the hopper and is slideable to a second position for selectively sealing the upper end of the hopper. An actuator is provided for selectively controlling the movable element of the hopper for dropping the sample into a crucible aligned below the hopper.

Abstract: 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.

Abstract: A crucible assembly for use in an analytical furnace for the fusion of a sample includes a graphite heating crucible of cylindrical construction having one end open and an enclosed lower end with a positioning member interior to the interior cylindrical wall for receiving and positioning a separate sample holding crucible of cylindrical construction having an open upper end and an enclosed lower end. The heating crucible has an annular upper contact surface for engaging a first electrode and an annular lower contact surface for engaging a second electrode and positions the sample holding crucible in the zone of maximum heat in spaced relationship from the opposite ends of the heating crucible.

Abstract: A combustion analyzer for the analysis of the carbon and sulfur content in steel includes a gas flow system whereby a carrier gas flows through a combustion chamber and gaseous by-products of combustion flow through one or more infrared cells for analysis. In order to correct for the inherent nonlinearity of the measurement of concentration by the infrared cell or cells, a linearity correction system is provided. In the linearity correction system, discrete levels of concentration of known gases are dosed into the system and the detected concentration measured. Scaling factors are determined by an iterative process employing a microprocessor which scaling factors are then employed to correct for the nonlinearity in sample measurements. In one embodiment of the invention, the flow of the specimen gas employed for dosing the system is measured as a function of the pressure differential across a given size flow restrictor using an improved control valve and dosing manifold.

Abstract: 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.

Abstract: A copper sleeve is employed to join a molybdenum disilicide heating rod with a conductor by a brazing process including fluxing the interior of the sleeve, positioning the sleeve partially over one end of the heating rod and heating the junction of the sleeve and rod in a nonoxidizing flame while applying a brazing alloy to the interior of the sleeve. The conductor is then crimped to the opposite end of the sleeve for providing an electrical and mechanical connection of the conductor to the heating rod.

Abstract: A system for stepwise advancing a row of crucibles individually through a loading station of an induction furnace includes a plurality of articulated fingers for gripping each of the crucibles. The fingers are mounted to a first slide for movement along the direction of advancement of the crucibles. The first slide is mounted to a second slide for advancing and retracting the fingers into crucible engaging and disengaging positions, respectively. Control means are provided for controlling the movement of the slides and the articulated fingers sequentially to stepwise advance the crucibles through the loading station.

Abstract: For use in a combustion furnace for analytical apparatus in which a specimen is combusted in a combustion chamber and gases therefrom are withdrawn for analysis, a cleaning apparatus mounted at one end of the combustion chamber. The cleaning apparatus includes a housing sealably mounted to the combustion chamber and containing a movable cleaning element for abrading the interior walls of the combustion chamber. A shield is positioned between the cleaning element and the combustion chamber such that during combustion of a specimen, the cleaning element is effectively shielded from the high temperature combustion. In one embodiment, the housing also includes a filter between gas supply and exhaust passages and apparatus for self-cleaning of the filter.

Abstract: A closure mechanism for a metallographic sample pressure molding system includes a mold cylinder having a bayonet socket for receiving a closure member which includes an upper ram mounted thereto for lockably enclosing the mold chamber defined by the cylinder. The closure member includes a cam and means for actuating the cam for moving the upper ram an incremental distance to break flashing from the molded metallographic specimen once cured for facilitating removal of the specimen and its surrounding thermoset or thermoplastic mount. In the preferred embodiment, the mold cylinder is demountable to a mold collar at an end remote from the closure member. A piston extends into the mold chamber through the collar and an alignment coupling joins the piston to a piston rod facilitating installation of the mold cylinder to the collar. The system provides a positive locking mold chamber with easy access and facilitates removal of the molded article by breaking the flashing from the article once molded.

Abstract: The specification discloses a ceramic nozzle of the submersible type which includes a permeable bore section surrounded by an annular manifold positioned between the bore section and the less permeable integral body of the nozzle. The manifold is employed for supplying inert gas into the nozzle bore. The nozzle is made by positioning an unfired ceramic bore section on a mandrel inserted into a mold cavity defining the body of the nozzle with the outer surface of the bore section covered with a burnout material which, during the molding of the nozzle, fills the manifold area and after kiln firing burns away to leave a void defining the manifold. The ceramic mix for the bore section includes burnout material, such that after firing the bore section is significantly more permeable than the body of the nozzle.

Abstract: An instrumentthat determines the HF and the HNO.sub.3 concentration or other mixed acids or single acid of an acid bath measures the potential difference between a fluoride ion selective electrode and a reference electrode and the potential difference between a hydrogen ion selective electrode and the reference electrode. The electrode voltages are applied to a control circuit including a microprocessing unit for calculating and displaying the acid concentrations of the bath and for compensating for the nonlinearity of the measured voltages as well as the interdependence of the two voltages. Also, means are provided for calculating and displaying percent metal concentrations.

Abstract: An electrode system for resistance furnace includes a pair of electrodes, one of which is movable to selectively clamp a resistive crucible between the electrodes. A specimen placed in the crucible is combusted by the application of electrical power to the electrodes in electrical contact with the crucible. One of the electrodes includes a demountable housing extending therefrom for surrounding a crucible held between the electrodes and sealing the crucible between the electrodes. The demountable housing permits easy cleaning of the system by removal of the housing. In one embodiment one of the electrodes includes a surface configurated to engage the crucible and provide self-centering of the crucible as the electrodes are moved to clamp the crucible therebetween.

Abstract: Lead germanate, Pb.sub.5 Ge.sub.3 O.sub.11, or lead germanate/silicate in which up to 2/3 on a molar basis of the germanium has been substituted with silicon, can be formed from a glassy state to a ferroelectric state by a simple annealing process. The lead germanate or lead germanate/silicate is heated to a temperature sufficient to anneal it into a crystalline phase, then cooled below the ferroelectric transition temperature for the composition while an electric field is applied.

Abstract: An arc control circuit supplies voltage to an electrode of a portable analyzer for striking an arc against a specimen to provide an aerosol of the specimen material for analysis. The circuit includes a source of voltage and voltage dividing means for selectively applying different proportions of the source voltage to the electrode. Sensing means are coupled to the electrode for actuating bypass switching means coupled to the voltage dividing means when the electrode has made contact with the specimen to apply the full voltage of the power supply to the electrode to start the arc. As the electrode tip is withdrawn from the sample a predetermined distance, the desired arc is maintained. Means are provided for quenching the arc by opening the bypass switch to lower the electrode voltage once the arc has been maintained for a desired amount of time.