Liquid purification or separation – With means to add treating material – Chromatography
Reexamination Certificate
2000-04-04
2002-03-26
Therkorn, Ernest G. (Department: 1723)
Liquid purification or separation
With means to add treating material
Chromatography
C210S232000, C210S446000, C210S656000, C096S101000
Reexamination Certificate
active
06361687
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fittings used to connect miniature fluid conduits, and especially fittings used to connect miniature fluid conduits utilized in liquid chromatography.
BACKGROUND OF THE INVENTION
Numerous types of equipment used for the analysis or purification of chemical compounds utilize miniature fluid conduits, such as metallic tubing, within which liquid samples pass through the system. For example, liquid chromatography is a technique in which a column is packed with a packing material, an analyte is introduced into one end of the column, and a carrier fluid is then run through the column. The length of time that the analyte is retained within the column can enable analysis and identification of the analyte. A popular form of liquid chromatography is High Performance Liquid Chromatography (HPLC) in which the sample is pumped through the column under an elevated pressure, typically at 300 to 6,000 psi.
Liquid chromatography systems, such as HPLC systems, typically include several components, for example; a pump; an injection valve for injecting the analyte; a precolumn filter to remove particulate matter in the analyte solution that might clog the column; a guard column to retain irreversibly adsorbed chemical material; the HPLC column itself; and a detector that analyzes the carrier fluid as it leaves the column. These various components may typically be connected by a miniature fluid conduit, such as metallic or polymeric tubing, usually having an internal diameter of 0.005 to 0.040 inch. All of these various components and lengths of tubing are typically interconnected by threaded fittings. Often, a first internally threaded fitting seals to a first component with a ferrule or similar sealing device. The first fitting is threadedly connected through multiple turns by hand or by use of a wrench or wrenches to a second fitting having a corresponding external fitting, which is in turn sealed to a second component by a ferrule or other seal. Disconnection of these fittings for component replacement, maintenance or reconfiguration again requires the use of a wrench or wrenches to unthread the fittings. Most thread connections are 10-32, ¼-28 or 6 mm×1. If a hand-tightened threaded fitting is used, it may not stand up to the extreme pressures of HPLC.
SUMMARY OF THE INVENTION
The present invention provides a quick connect fitting assembly for coupling first and second analytical fluid conduits. The assembly includes a first fitting defining a central passage for receiving the first fluid conduit therein, the first fitting defining at least one first radial engaging surface, and a second fitting defining a central passage for receiving the second fluid conduit therein. The assembly further includes an annular nut rotatably mounted on the second fitting, wherein the nut defines at least one second radial engaging surface, wherein the nut is selectively rotatable less than 360° relative to the first fitting to engage the first and second engaging surfaces to create a secure seal between the first and second fittings for fluid flow communication between the first and second fluid conduits.
A preferred embodiment of the present invention provides a quarter turn quick connect fitting assembly, including a first fitting having radially projecting connecting protrusions and a second fitting having grooves which receive the connecting elements, which is operable by twisting one of the components by less than a full turn, preferably by a ¼ turn. Both the first and second fittings define a central passage which may be configured to slidably receive a hollow tube, or which may be internally threaded to threadedly receive an externally threaded mating fitting. The first and second fittings are selectively connected by sliding the connecting elements of the first fitting into the grooves of the second fitting and rotating the quarter turn nut through approximately 90° with respect to the first fitting. The connecting elements are thereby securely seated within angled areas at the inner ends of the grooves.
In a first preferred embodiment of the quarter turn quick connect fitting, the first fitting includes a body having a proximal end and a distal end. Two pins radially project from the distal end of the first fitting. The body of the first fitting defines a central passage extending from the proximal end of the first fitting to a centrally located recess on the distal end of the first fitting. The central passage can be configured to slidably receive a hollow tube set, or to threadedly receive an externally-threaded mating fitting. The second fitting includes a body having a proximal end and a distal end. A central passage extends from the proximal end of the first fitting to a centrallylocated recess on the distal end of the first fitting. The central passage can be configured to slidably receive a hollow tube set, or to threadably receive an externally-threaded mating fitting. The second fitting is mounted within a rotatable nut, and is biased therein by at least one spring washer. The rotatable nut has a proximal end and a distal end, and includes two spiral grooves which open onto the distal end of the nut. The two spiral grooves receive the two dowel pins of the first fitting, thereby coupling the first fitting to the quarter turn nut, as set forth above. A compressible sealing element, having a body defining a central passage, is located between the first and second fittings and forms a seal when the first and second fittings are locked together. The central passages of the first fitting, the sealing element and the second fitting thus form a continuous, sealed passage within which there is no deadspace to reduce or interrupt fluid flow therein, or cause band broadening of the analyte sample.
A second preferred embodiment of the present invention is similar to the first preferred embodiment, except that the central passage of the first fitting is beveled at the proximal end and is configured to slidably receive an HPLC column end fitting. The first fitting is externally threaded and is retained on the column end by means of an internally threaded nut mounted coaxially around the HPLC column end fitting and which is screwably attached to the externally threaded surface of the first fitting. A seal is formed between the beveled surface of the central passage of the first fitting and a ferrule mounted coaxially around the HPLC column end fitting.
A third preferred embodiment of the present invention is similar to the first preferred embodiment, except that the central passage of the first fitting is internally threaded to receive the externally threaded end of a BPLC column.
In a fourth preferred embodiment of the present invention, the quarter turn quick connect fitting includes a first fitting having a central passage internally threaded to receive a HPLC column end fitting, as described for the third preferred embodiment, and a second fitting located within a quarter turn nut. The fourth preferred embodiment of the present invention further includes an adapter having a body defining a central passage. The adapter body has a proximal end and a distal end, the proximal end having two grooves and the distal end having two radially projecting dowel pins. The central passage of the adapter is configured to receive a guard column. The first fitting is connected to the adapter by rotatably inserting the dowel pins of the first fitting into the grooves of the proximal end of the adapter. The second fitting is connected to the adapter by rotatably inserting the dowel pins of the distal end of the adapter into the grooves of the distal end of the quarter turn nut.
In a fifth preferred embodiment, the quarter turn quick connect fitting includes a first fitting, a second fitting located within a quarter turn nut, and a frit composed of a sintered material that filters the fluid passing therethrough. The frit is housed within a frit ring composed of a deformable material that forms a seal between the first and second fitting within th
Ford Douglas W.
Levanen Derrick S.
Martin John T.
Christensen O'Connor Johnson & Kindness PLLC
Optimize Technologies, Inc.
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