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Sanitary diaphragm pump for critical bioprocess applications

Sanitary diaphragm pump for critical bioprocess applications description/claims

The present application claims priority to provisional patent Application Ser. No. 60/679,524, filed May 10, 2005. This earlier filed provisional application is incorporated herein by reference.

Many fluid handling applications in biotechnology require a pump to move the fluid. Generally, when handling biological fluids it is important to ensure that an uncontaminated environment has been maintained throughout the process. Thus, the pumps are designed to be easily cleaned and sanitized before and after each use, thus controlling or reducing microbial contamination. In particular, contemporary biotechnological filtration and/or chromatography require equipment to be sanitized prior to use in order to ensure a fluid handling environment with minimal microbial contamination.

In some chromatography processes, one or several liquid solutions are pumped into a chromatography column filled with a resin which varies depending on the particular process. The liquid flow rate must be constant and accurately controlled, while maintaining a relatively high degree of pressure (several bars/atmospheres or more) in order to drive the liquid through the column. Similarly, in a filtration process a relatively high degree of pressure is used to drive a liquid through a filter (normal or direct flow) or across a filter (cross or tangential flow). The latter is commonly used when liquid is re-circulated across a filter membrane. In such cross flow applications a precise flow rate and high pressure is required to ensure that more than a minor percentage of fluid flows through the filter relative to the recirculation rate. The high pressure is required to help drive the liquid through certain filters (such as membrane or cross-flow ultra-filters) that resist or limit the passage of fluid. Thus, as in chromatography, the fluid flow rate in filtration must often be accurately controlled, while maintaining several bars/atmospheres or more of pressure.

Peristaltic pumps are commonly used in biotechnological applications because they do not contact the liquid stream but only the outside of the process tubing, only the inner diameter of the process tubing comes in contact with the liquid stream. They operate by means of a constriction that moves along the tubing, thus its parts avoid contact, and thus contamination, of the handled liquid. However, such tubing pumps are limited to lower pressure applications. A high pressure environment, such as several bars/atmospheres requires heavier gauge or reinforced tubing, which is no longer flexible enough to be pinched or squeezed. Thus, the peristaltic pumps are not suited for high pressure environments.

Sanitary rotary lobe pumps are commonly used in biotechnology processes. These pumps can operate at relatively high pressures but they contain numerous components, such as the pump rotors, that contact the liquid stream. The contaminated components must be cleaned and sanitized after each use and possibly disassembled. Such a process can have added costs and delays that are not desirable. Also, this process requires high quality components that can withstand the added wear, which can also increase costs. Additionally, the type of precision components generally used as well as the relatively large number that get contaminated with each use, makes those parts too valuable to throw away after a single or small number of uses.

It is therefore desirable to provide a fluid pumping system that is suitable for relatively high pressure environments, while preferably maintaining a constant and accurate fluid flow rate. Also, the system must be easily sterilized or uncontaminated between uses.

The present invention relates to an apparatus for pumping fluids that is easily cleaned and/or sterilized after each use. Preferably, any parts contaminated by fluid contact can be easily removed and replaced. Also, those contaminated parts should be easily sterilized or designed to be disposable and thus replaced with inexpensive replacements. Using the preferred diaphragm pump of the present invention, few elements ever come in contact with the handled fluid, while providing a low shear, efficient, low cost method and system of pumping biological fluids. Additionally, the invention provides an apparatus and system that provides a constant and accurate fluid flow rate, while able to operate in relatively high fluid pressure environments.

In one aspect of the present invention, a fluid pumping apparatus is provided that includes a first pump housing including a first inner chamber. The first pump housing includes a fluid access port adapted to provide fluid communication between an outside of the first pump housing and the first inner chamber. Also, included is a second pump housing having a first coupling flange securedly mated to the first pump housing. The second pump housing includes a second coupling flange adapted to be removeably and securedly mated to a third coupling flange on a piston housing. Additionally, a flexible diaphragm is provided disposed between the first and second pump housings. The diaphragm is in fluid communication with the first inner chamber. Also, the diaphragm is adapted to be displaced by a driven piston for expelling fluid from the first inner chamber.

In another aspect of the present invention a fluid pumping apparatus is provided that includes a first pump housing with a first inner chamber. The first pump housing includes a fluid access port adapted to provide fluid communication between an outside of the first pump housing and the first inner chamber. A second pump housing is provided that includes a second inner chamber. The second pump housing is secured to the first pump housing. Further provided is a flexible diaphragm disposed between the first and second pump housings. The diaphragm is in fluid communication with the first inner chamber. Yet further, a third pump housing is provided that is removeably secured to the second pump housing. The third pump housing includes a piston access port. Also, the first, second and third pump housings are adapted to form a continuous unitary outer pump shell. Additionally a driven piston is adapted to move the flexible diaphragm toward the fluid access port.

In yet another aspect of the current invention a chromatography pump assembly is provided that is adapted to deliver fluid at a constant flow rate. The pump assembly comprising a first conduit for receiving fluid, a second conduit for expelling fluid, a first and second diaphragm pump in fluid communication with the first and second conduits and a valve system. Each pump includes an inner fluid chamber, an inner flexible diaphragm, and a rigid drive mechanism adapted to push the diaphragm thereby expelling fluid from the inner fluid chamber. The valve system is adapted to block fluid flow from the first conduit to one of the first and second pumps, while simultaneously blocking fluid flow to the second conduit from the other of the first and second pumps.

In yet another aspect of the current invention a method for pumping a fluid is described comprising providing conduit adapted to communicate fluid from at least one source to at least one destination. Then, coupling a first disposable and/or sterilized diaphragm pump to an intermediate position of the conduit. The first diaphragm pump is adapted to expel fluid by activation of a driven piston. Additionally, securing a piston housing for the driven piston to the first pump. Thus, the piston housing and the first pump forming a unitary continuous outer pump shell. Then, initiating the driven piston thereby pumping fluid out of the diaphragm pump. Thereafter, removing and discarding the first diaphragm pump after a single use, and replacing the first diaphragm pump with a second diaphragm pump. The second diaphragm pump being disposable and/or sterilized prior to use as part of the assembly.

These and other objectives, features, and advantages of this invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.

FIG. 1 is a cross-sectional view of an embodiment of a fluid pumping apparatus in accordance with the subject invention.

FIG. 2 is an exploded cross-sectional view of an upper pump housing, fluid conduit and valve assembly, in accordance with the subject invention.

FIG. 3 is a cross-sectional view of an alternate embodiment of the upper pump housing shown in FIG. 2, in accordance with the subject invention.

• Provisional Patent
• Utility Patent

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