Optics: measuring and testing – By dispersed light spectroscopy – With sample excitation
Reexamination Certificate
2002-05-10
2004-12-07
Evans, F. L. (Department: 2877)
Optics: measuring and testing
By dispersed light spectroscopy
With sample excitation
C356S417000
Reexamination Certificate
active
06829048
ABSTRACT:
This application claims priority of pending German Patent Application 101 22 873.2 filed on May 11, 2001.
FIELD OF THE INVENTION
The invention relates to a flame atomization device, especially for an atom absorption spectrometer, with at least one mixer chamber and an atomizer leading into said mixer chamber, and with a burner head mounted on the mixer chamber's burner connection piece.
Such a flame atomization device for an atom absorption spectrometer serves to bring a sample into a measurable atomic state. For this purpose, the sample is introduced by the atomizer, especially in the form of aerosol, into the mixer chamber. There, the sample is mixed with a fuel gas and conducted to the burner head via the burner connection piece. Then the fuel gas enriched with the sample combusts inside the burner head. The sample stimulated by the flame can be analyzed by the atom absorption spectrometer. In the course of regular operation, the speed with which the fuel gas enriched with the sample escapes exceeds the speed of combustion. Consequently, the corresponding flame is always found outside the mixer chamber or burner connection piece. Yet a certain kind of error, such as leaks or the use of laughing gas, may lead to flashbacks of the flame. Laughing gas for example, can lead to a very high combustion speed and is therefore difficult to handle.
During such a flashback of the flame, the flame burns inside the burner head, in the area of the burner connection piece, and possibly even in the remaining area of the mixer chamber. These areas possess comparatively large cross-sections in which the speed of the gas is low. This results in an explosion-like blow-up and a corresponding explosive excess pressure. Yet such an explosive excess pressure must not lead to the destruction of the components, and in addition, the flame atomization device should safely switch off in case such an excess pressure occurs.
With flame atomization devices currently in use, in cases of such explosive overpressure a corresponding pressure release was ensured, for instance by means of a burner head that flies off. The burner head was secured by a rope or other recovery devices. With other flame atomization devices, such a pressure relief occurred, for example, through a pretensioned pressure release valve.
Finally, there are known flame atomization devices, which use additional pressure relief devices such as removable plugs, a bursting disk, or something similar.
BACKGROUND OF THE INVENTION
The flame atomization devices known from practice have the disadvantage of requiring additional parts, and of needing comparatively great cost when they have to be restored to working condition. Moreover, additional sealing areas are often required, which must be considered potential sources of errors.
The aim of the flame atomization device based on the invention is therefore to improve a device such as initially described, in such a manner as to provide a simple construction for pressure release, or respectively, pressure reduction, and at the same time, to restore the flame atomization device to working condition simply and quickly.
This aim is achieved by mounting a slip casing that can be adjusted between a closed position and an open position in relation to the burner connection piece. At the same time, in the open position, at least one pressure reduction outlet is opened in the burner connection piece.
Because of the sliding of the slip casing, it is unnecessary to include a component that flies off, or a component that is to be destroyed by the pressure. This also obviates the need to mount a comparatively complex pressure relief valve. When a correspondingly high degree of overpressure builds up, the slip casing automatically slides into its open position, and the pressure is reduced through the burner connection piece's pressure reduction outlet. As a result, the pressure reduction outlet can be designed in such a way as to divert the escaping products without requiring additional, sensitive system parts. Likewise, such diversion may prevent injuries to personnel operating the device.
The slip casing may be located inside the burner connection piece in an adjustable manner. If the slip casing it is, for example, secured to the burner head in this position so that they move together, the slip casing may be slipped away together with the burner head when excess pressure occurs, and as a result, the pressure reduction outlet opens. Yet in order to configure the flame atomization device based on the invention in a simpler way and to avoid creating additional dead space inside the mixer chamber, which may lead to test delays between different samples, the slip casing can be mounted onto the burner connection piece from the outside. In this manner no modifications are required inside the burner connection piece.
The slip casing may also be configured as a partial covering; that is, the casing may only extend along a specific portion of the circumference around the burner connection piece. At the same time, the slip-casing may, as described above, be fixed to the burner head and, for example, be held in position by it, fitting tightly along one of the burner connection piece's outer walls. If in such a case, the burner head moves because of excess pressure inside the mixer chamber, the slip casing or partial casing will move accordingly, as well, and the pressure reduction outlet is opened. Yet in order to enable the slip casing to be mounted independently from the burner head or from other parts of the flame atomization device, the slip casing may possess a slip mantle that encloses the burner connection piece. In this manner, the slip casing itself may be attached to the burner connection piece so that it is movable.
In order to fasten the slip casing to the burner head in a way that it can move only between the closed and open positions and cannot detach from the burner head by itself, the slip casing may be fastened to the burner connection piece by a clip.
In order to limit the slip casing's freedom of movement between the closed and open positions, the slip casing may be mounted in a movable manner between the closed and open positions, yet at the same time be secured tightly onto the burning connection piece itself, in a way that prevents it from turning.
There are several ways to ensure such a type of mounting. A simple construction may include an essentially rib-like securing protrusion extending from the slip casing and/or the burner connection piece. This protrusion engages in a corresponding securing recess at the respective opposite part of the tightly secured, but axially movable bearing. In this manner, only one component is needed to ensure the mounting between the slip casing and the burner connection piece. At the same time, the closed and open positions may be determined by the sliding motion of the securing protrusion inside the securing recess. For example, the closed position may be determined by the securing protrusion's contact with one end of the arresting recess, and the open position may be accordingly defined by the securing protrusion's contact with the arresting depression's other end.
In order to prevent the slip casing from getting wedged during its axial movement, it could be of advantage to arrange two securing protrusions, and their corresponding arresting depressions, diametrically opposite each other.
Within this context, it has to be noted that it is, of course, possible to design a securing protrusion on the slip casing as well as on the burner connection piece. In this case, accordingly, there is one securing recess each on the slip casing or the burner connection piece. The securing protrusions and recesses of the different components are arranged in such a way, in relation to each other, that they engage each other as soon as the slip casing is in position. In addition, it must be noted that the slip casing may also be clipped onto the burner connection piece by means of the securing protrusion and the arresting depression. For example, th
Berthold GmbH & Co. KG
Evans F. L.
St. Onge Steward Johnston & Reens LLC
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