CHROMATOGRAPHY PUMP
The invention relates to a chromatography pump, comprising a cylinder (202, 402) in which a piston (204, 404) is arranged for a reciprocating movement; a front element (208) provided with a cylinder head area (210) which together with the cylinder (202, 402) and the piston (204, 404) defines a cylinder space (212); an inlet valve (214) and an outlet valve (216) arranged in the front element (208); an inlet channel (218) arranged in the front element (208) between the inlet valve (214) and the cylinder head area (210); an outlet channel (220) arranged in the front element (208) between the cylinder head area (210) and the outlet valve (216). The inlet channel (218) and outlet channel (220) extend in a substantially straight direction, so that air bubbles (234) are prevented from being trapped within the inlet and outlet channels (218, 220).
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The present invention relates to a chromatography pump according to the preamble of claim 1.
Chromatography is a chemical process for identifying and quantifying compositions held in a sample and also for purification and extraction of compositions. In the process, compositions in a solution are separated from each other as the solution moves through a stationary material held in a column.
The solution is pumped under high pressure through the stationary material in the column by one or several chromatography pumps.
BACKGROUND ARTIn chromatography and especially in liquid chromatography often only very small samples of the material to be analyzed or purified are available. The process during mixing gradients of two different liquids is also sensitive for rapid changes in the flow and pressure of solution as it moves through the stationary material in the column. For this reason the chromatography pump system has to be very accurate in order to achieve a minimum of fluctuation in flow output and pressure from the chromatography pump.
In the preparation for the chromatography process air held in the chromatography pump has to be removed. Also, air held in the sample has to be removed. Therefore, chromatography pump systems often are provided with a purging arrangement which removes the air held in the chromatography pump in the beginning of the process. The purging arrangement generates a vacuum at the outlet valve of the pump, so that air held within the pump is sucked out from the pump and the solution or sample simultaneously is sucked into the pump.
However, to some extent air bubbles tend to be trapped within the chromatography pump cylinder even if the purging arrangement has removed the major volume of air held in the chromatography pump. The air bubbles trapped within the chromatography pump reduces the performance of the chromatography pump, so that the pressure and flow of the solution will fluctuate. This will influence on the overall chromatography mixing process, so that less accurate results will be achieved.
In a chromatography pump available in the prior art, which will be described in more detail below together with
The object of the invention is to achieve a chromatography pump with automatic purging, which eliminates manual means for the purging operation.
Another object of the invention is to achieve a chromatography pump which facilitates air bubbles to be transported through the pump.
A further object of the invention is to achieve a chromatography pump in which air bubbles are prevented to be trapped.
A further object of the invention is to achieve a minimum of fluctuation in flow output and pressure of a chromatography pump.
These objects are achieved by a chromatography pump according to claim 1.
Since the inlet channel and outlet channel extend in a substantially straight direction there are no edges and corners where air bubbles can be trapped within the channels. Instead the air bubbles will pass through the cannels without influencing the performance of the chromatography pump. Thus, a chromatography pump with high performance is achieved.
According to an aspect of the invention an outlet of the inlet channel arranged in the cylinder head area has a substantially elliptic configuration. This configuration facilitates air bubbles to be transported out of the inlet channel and further to the outlet channel.
According to a further aspect of the invention a cavity is arranged in the cylinder head area and an inlet of the outlet channel is arranged in the cavity. Thereby, air bubbles coming from the inlet channel and air bubbles in the cylinder will easily be transported out to the outlet channel.
According to a further aspect of the invention the cavity has a form substantially corresponding to an arch. This configuration facilitates the transport of air bubbles out to the outlet channel.
According to a further aspect of the invention the front element is made of PEEK material, titanium or hastelloy. Thereby, a high strength of the front element is achieved. Also, the surface properties of these materials can be adapted to prevent air bubbles to be trapped and tied on the surfaces in the channels and in the cylinder.
According to a further aspect of the invention the surface roughness (Ra) of the walls of the inlet and outlet channels and of the wall of the cylinder head area are between 0.2-2.0, preferably between 1.0-2.0. This will prevent air bubbles to be tied to the surface of the inlet and outlet channels and of the wall of the cylinder head area.
According to a further aspect of the invention the inlet and outlet valves are check valves provided with seated balls in which a weight arranged on the ball urges the ball against the seat. Thereby, air bubbles are prevented from being trapped between the ball and the seat due to the force from the ball on the seat. Also, between the ball and the inner wall of the valve capillary forces caused by air bubbles make the ball get stuck to the inner wall. This is prevented by the weight arranged on the ball.
According to a further aspect of the invention the cylinder head area has a normal which substantially coincides with the axis of the piston. Thus, a compact design of the cylinder space is achieved. Because the inlet and outlet channels are connected to the cylinder head area and that the normal of the cylinder head area substantially coincides with the axis of the piston air bubbles in the cylinder will easily be transported out to the outlet channel.
Further aspects, advantages and features of the invention can be derived from the following detailed description of exemplary embodiments of the invention, with reference to the drawings.
When the piston 104 thereafter changes direction and moves in the right direction in
However, air bubbles 134 tend to be trapped within the known chromatography pump 101 disclosed in
As mentioned above the air bubbles 134 trapped within the chromatography pump 101 reduces the performance of the pump 101, so that the pressure and flow of the liquid 122 will fluctuate. This will influence on the overall chromatography process, so that less accurate results will be achieved.
When the piston 204 thereafter changes direction and moves in the right direction in
The inlet and outlet channels 218, 220 in
The surface roughness (Ra) of the walls 236 of the inlet and outlet channels 218, 220 and of the wall 238 of the cylinder head area 210 are between 0.2-2.0, preferably between 1.0-2.0.
This will prevent air bubbles 234 to be tied to the wall 236 of the inlet and outlet channels 218, 220 and of the wall 238 of the cylinder head area 210. The surface roughness can be achieved by special machining techniques. The front element 208 is preferably made of PEEK material, titanium or hastelloy. Other materials are also possible. PEEK and hastelloy are registered trademarks. Thereby, a high strength of the front element 208 is achieved. Also, the surface properties of these materials can be adapted to the above-mentioned surface roughness values. The liquid 222 must be pumped under high pressure through the stationary material 232 in the column 230. Therefore, the materials used in the front element 208 must have high strength properties.
The cylinder head area 210 has a normal 246 which substantially coincides with the axis 248 of the piston 204. Thus, a compact design of the cylinder space 212 is achieved. Since the inlet and outlet channels 218, 220 are connected to the cylinder head area 210 and that the normal 246 of the cylinder head area 210 substantially coincides with the axis 248 of the piston 204 air bubbles 234 in the cylinder 202 will easily be transported out to the outlet channel 220.
The chromatography pump 201, 301, 401 according to the present invention is primary designed for pumping liquid 222. However, other fluids may also be pumped by the chromatography pump 201, 301, 401 according to the invention.
Claims
1. A chromatography pump, comprising a cylinder (202, 402) in which a piston (204, 404) is arranged for a reciprocating movement along an axis (248); a front element (208) provided with a cylinder head area (210) which together with the cylinder (202, 402) and the piston (204, 404) defines a cylinder space (212); an inlet valve (214) and an outlet valve (216) arranged in the front element (208); an inlet channel (218) arranged in the front element (208) between the inlet valve (214) and the cylinder head area (210); an outlet channel (220) arranged in the front element (208) between the cylinder head area (210) and the outlet valve (216), wherein the inlet channel (218) and outlet channel (220) extend in a substantially straight direction, and in that the inlet channel (218) and outlet channel (220) each extend obliquely to the axis (248).
2. The pump of claim 1, wherein a cavity (242) is arranged adjacent the cylinder space (212)and in that an inlet (244) of the outlet channel (220) is arranged in the cavity (242).
3. The pump of claim 2, wherein an outlet (240) of the inlet channel (218) is arranged in the cavity (242).
4. The pump of claim 2, wherein the cavity (242) has a form substantially corresponding to an arch, so that air bubbles (234) are prevented from being trapped within the cavity (242).
5. The pump of claim 1, wherein the front element (208) is made of PEEK material, titanium or hastelloy.
6. The pump of claim 1, wherein the surface roughness (Ra) of the walls (236) of the inlet and outlet channels (218, 220) is between 0.2-2.0, preferably between 1.0-2.0.
7. The pump of claim 1, wherein the surface roughness (Ra) of the wall (238) of the cylinder head area (210) is between 0.2-2.0, preferably between 1.0-2.0.
8. The pump of claim 1, wherein the inlet and outlet valves (214, 216) are check valves provided with seated balls (226) in which a weight (303) arranged on the ball (226) urges the ball (226) against the seat (228).
9. The pump of claim 1, wherein the cylinder head area (210) has a normal (246) which substantially coincides with the axis (248) of the piston (204).
10. The pump of claim 1, wherein the chromatography pump (201, 301, 401) is designed for pumping liquid (222).
11. The pump of claim 1, wherein a circumferential seal (405) is arranged on the piston (404), and a circumferential leaf spring (407) is arranged to apply an outwardly directed radial load on the seal (405).
12. The pump of claim 11, wherein a tap (409) is arranged on an end part (411) of the piston (404), which tap (409) is attached to the piston (404) and fixates the seal (405) on the end part (411) of the piston (404).
13. The pump of claim 1, wherein the outlet channel (220) and the inlet and outlet valves (214, 216) extend in a substantially coincident direction, so that the pump may be mounted with outlet channel (220) in a substantially vertical direction in relation to a horizontal plane (308).
Type: Application
Filed: Nov 24, 2011
Publication Date: Oct 3, 2013
Applicant: GE HEALTHCARE BIO-SCIENCES AB (Uppsala)
Inventors: Owe Salven (Uppsala), Bjorn Olovsson (Uppsala), Mats Lundkvist (Uppsala), Jan Kranse (Ostervala)
Application Number: 13/990,754
International Classification: F04B 53/16 (20060101);