Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
1998-07-31
2001-08-07
Soderquist, Arlen (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C422S091000
Reexamination Certificate
active
06270727
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to crucibles for fusion of a specimen for analysis and particularly to a porous ceramic crucible.
Analyzers for the determination of elements such as carbon, nitrogen, hydrogen, oxygen, sulfur or other substances, such as protein, rely upon the combustion of a weighted quantity of a sample in a gas flow-through system for determining the byproducts of combustion. The gases are passed through absorption and purification stages and supplied to an analyzer to measure the resultant elements of interest. One such analyzer is disclosed in U.S. Pat. No. 4,573,910 assigned to the present assignee. Typically, such analyzers integrally include a furnace which may be a resistance furnace, induction furnace or other type furnace which heats a specimen within a crucible to combustion temperatures in the range of 1000° C. To assist in complete combustion, typically a lance tube is employed and directs a carrier gas into the open mouth of the crucible during heating to facilitate combustion of the sample. The gaseous byproducts of combustion subsequently flow around the outer periphery of the lance tube and/or crucible into the analyzer from the furnace.
The difficulty with such system is that the crucibles frequently can only be used for approximately 40 to 80 analyses. Accordingly, there exists a need for a crucible which not only can be used repeatedly but which also promotes the release of specimen gases during combustion.
SUMMARY OF THE PRESENT INVENTION
The crucible of the present invention satisfies this need by providing a ceramic crucible which can be in the form of a cup-shaped member having an integral floor and a generally cylindrical side wall or a cylindrical member plugged at one end with a suitable material, allowing the sample to be held within the crucible so-defined and having openings to allow gases to pass through the side wall of the crucible. In a preferred embodiment of the invention, the crucible, is made of a porous ceramically-bonded alumina having a mean pore diameter of from about 150 to 350 microns. The porous ceramic crucible is manufactured of a mixture of at least about 92% alumina and about 7.5% silica with trace amounts of titanium dioxide and potassium oxide. The reticulated ceramic crucible so-formed allows gases to pass through the side wall and also allows a number of combustion cycles to be run. Crucibles embodying a preferred embodiment of the invention, therefore, include a floor and have side walls with apertures formed therein which allow the passage of analytical gases through the side wall of the crucible. The material remaining after analysis can successively build up from the floor of the crucible with the unplugged apertures of the crucible side wall above the floor allowing successive combustion cycles until the crucible becomes substantially filled with residue or slag from previous analytical cycles. As can be appreciated, such construction allows a crucible to be used repeatedly as long as sufficient gas flow remains available through the side wall of the crucible. As a result, the cost of each analysis is substantially reduced in view of the ability to successively use the same crucible without replacement. The speed at which analytical cycles can be performed is improved by not having to remove and replace the crucible as frequently.
These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings.
REFERENCES:
patent: 1743803 (1930-01-01), Arensberg et al.
patent: 2930602 (1960-03-01), Rohn
patent: 3100155 (1963-08-01), Wagner
patent: 3281596 (1966-10-01), Williston
patent: 3403982 (1968-10-01), Fricioni
patent: 3619839 (1971-11-01), Kraus et al.
patent: 3650823 (1972-03-01), Mead et al.
patent: 3824016 (1974-07-01), Woodriff et al.
patent: 3899627 (1975-08-01), Sitek et al.
patent: 4091970 (1978-05-01), Komiyama et al.
patent: 4303615 (1981-12-01), Jarmell et al.
patent: 4328386 (1982-05-01), Bredeweg
patent: 4573910 (1986-03-01), Bredeweg
patent: 4789140 (1988-12-01), Lirones
patent: 5064617 (1991-11-01), O'Brien et al.
patent: 5085582 (1992-02-01), Edler
patent: 5236353 (1993-08-01), Adani et al.
patent: 5246667 (1993-09-01), Hemzy et al.
patent: 5637809 (1997-06-01), Traina et al.
patent: 4104049 (1992-04-01), None
Aldrich Catalog 1988, pp. 1942-1946.
French James L.
Mitchell Joel C.
Leco Corporation
Price Heneveld Cooper DeWitt & Litton
Soderquist Arlen
LandOfFree
Analytical crucible does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Analytical crucible, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Analytical crucible will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2519016