Check Valve Arrangement for a Transfer Pump and a Method of Using the Same

Abstract

A positive displacement pump 100 for pumping a fluid comprising a valve assembly 110 comprising a pressure responsive suction valve 115 and a pressure responsive delivery valve 120, the suction valve and the delivery valve each being moveable between a respective open configuration and a respective closed configuration such that flow of fluid through the valve assembly is unidirectional. The suction and / or delivery valve may be gravity responsive. The valves may comprise a ball 121 and cage 122 valve. A method of pumping a fluid using the valve system.

Description

Technical Field The present disclosure relates to a checkvalve assembly for a transfer pump and a method of using the same, particularly, but not exclusively, to a check valve assembly for a transfer pump for unidirectional pumping of a liquid. Background Transfer pumps are widely used in various different fields to move liquids. However, there is always a need for improvement in efficiency in pumps to improve fluid transfer rates. There is therefore a need for a transfer pump that can both efficiently keep up with the increased demand for fluid transfer and can effectively run uninterrupted without the need for constant maintenance. The present invention results from Applicant’s work in using gravity to improve the efficiency of their transfer pump by using gravity to improve the efficiency of valves within their pump. Summary According to a first aspect of the current disclosure, there is provided a positive displacement pump for pumping a fluid. The pump comprises a valve assembly comprising a pressure responsive suction valve and a pressure responsive delivery valve. The suction valve and the delivery valve are each moveable between a respective open configuration and a respective closed configuration such that flow of fluid through the valve assembly is unidirectional. Optionally, the positive displacement pump has a preferred operating orientation relative to gravity. Optionally, the suction valve and / or the delivery valve are gravity responsive. Optionally, only one of the suction valve or the delivery valve are in their respective open configuration at one time. Optionally, the suction valve is in its open configuration and the delivery valve is in its closed configuration when fluid is being drawn into the positive displacement pump. Optionally, the suction valve is in its closed configuration and the delivery valve is in its open configuration when fluid is being pumped out of the positive displacement pump. Optionally, when the pump is in its preferred operating orientation relative to gravity, the suction valve and / or the delivery valve are forced towards their respective closed configurations by gravity. Optionally, the suction valve and / or the delivery valve are openable by pressure. Optionally, the suction valve and / or the delivery valve are closable by pressure. Optionally, the suction valve and / or delivery valve are openable by a combination of pressure and gravity. Optionally, the suction valve and / or delivery valve are closeable by a combination of pressure and gravity. Optionally, the suction valve and / or the delivery valve comprise a ball and cage valve. Optionally, the suction valve and / or the delivery valve are glove valves. Optionally, the suction valve and / or the delivery valve are gate valves. Optionally, the suction valve and / or the delivery valve are checkvalves. Optionally, the pump is a reciprocating positive displacement pump comprising a piston. Optionally, the piston comprises a rigid plate and a flexible seal. Optionally, reciprocal movement of the rigid plate causes positive displacement of fluid through the valve assembly. Optionally, the pump is a double acting positive displacement pump comprising two valve assemblies. According to a second aspect of the disclosure, there is provided a method for pumping a fluid, the method comprising using a positive displacement pump comprising a valve assembly comprising a pressure responsive suction valve and a pressure responsive delivery valve. The method further comprises increasing the pressure in the valve assembly; the pressure increase causing the delivery valve to open into an open configuration and the pressure increase causing the suction valve to close into a closed configuration such that fluid exits the valve assembly via the delivery valve. The method further comprises decreasing the pressure in the valve assembly; the pressure decrease causing the delivery valve to close into a closed configuration and the pressure decrease causing the suction valve to open into an open configuration such that fluid enters the valve assembly via the suction valve. Optionally, the positive displacement pump has a preferred operating orientation relative to gravity. Optionally, the suction valve and / or the delivery valve are gravity responsive, and wherein the gravity responsiveness results in the or each valve being forced towards their respective closed configurations by gravity when pump is in its preferred operating orientation relative to gravity. Further features and advantages of the first and second aspects of the present disclosure will become apparent from the claims and the following description. Brief Description of Drawings Embodiments of the present disclosure will now be described by way of example only, with reference to the following diagrams, in which:- Figure la shows a schematic cross-sectional view of the positive displacement pump during operation; Figure lb shows the positive displacement pump of Figure la at a different stage during operation; Figure lc shows the positive displacement pump of Figures la and lb at another different stage during operation; Figure 2 is a side view of the valve assembly; and Figure 3 is a perspective blown-up view of the components of the valve assembly. Detailed Description Figure la shows a schematic cross-sectional view of a positive displacement pump 100 during operation. In Figure la, the pump 100 is in the process of displacing fluid. The pump comprises a first valve assembly 1 lOi and a second valve assembly 1 lOii. The first valve assembly 1 lOi and the second valve assembly HOii are identical in their functions. The first valve assembly llOi and the second valve assembly HOii are reflections of each other relative to a central line A-A running down the centre of the pump 100. Each of the valve assemblies llOi, HOii comprises a pressure responsive suction valve 115i, 115ii (hereon referred to as 'suction valve’) and a pressure responsive delivery valve 120i, 120ii (hereon referred to as 'delivery valve’). The suction valves 115i, 115ii are located on a downward facing portion of the valve assemblies llOi, HOii when the pump 100 is in its preferred operating orientation. The delivery valves 120i, 120ii are located on an upward facing portion of the valve assemblies llOi, HOii when the pump 100 is in its preferred operating orientation. The delivery valves 120i, 120ii are located on opposing sides to the suction valves 115i, 115ii on their respective valves assemblies 1101, HOii. The suction valves 1151115ii each comprise a suction ball 1161116ii. The suction valves 115i, H5ii each comprise a suction valve cage 1171 117ii and a suction valve seat 119i, 119ii. The suction valve cage 1171117ii is designed to restrain the suction ball 116i, 116ii during inflow of fluid through the suction valve 1151115ii into the valve assemblies llOi, HOii. During outflow of fluid through the delivery valves 1201 120il the suction valves 115i, 115ii remain in a closed configuration in which fluid flow through the suction valve is prevented. During outflow, the suction valve balls 1161 116ii are forced through pressure and / or gravity into their respective suction valve seats 119i, 11911 maintaining a seal on the suction valves 1151 115ii. This ensures that flow through the valve assemblies 1101 11 Oh is unidirectional. When the positive displacement pump 100 is in its preferred operating orientation, the suction valves 115i, 115ii and delivery valves 120i, 120ii are configured such that gravity forces their respective suction valve balls 116i, 116ii and delivery valve balls 121i, 121ii into their respective suction valve seats 119i, 119ii and delivery valve seats 124i, 124ii. By responding to gravity, the suction valves 115i, 115ii and delivery valves 120i, 120ii can return to their respective closed configurations faster, thus increasing efficiency in terms of power used to pump the fluid and in terms of backflow. The delivery valves 120i, 120ii each comprise a delivery valve ball 12 li, 121ii. The delivery valves 120i, 120ii each comprise a delivery valve cage 122i, 122ii and a delivery valve seat 124i, 124ii. The delivery valve cage 122i, 122ii is designed to restrain the delivery valve ball 12li, 121ii during outflow of fluid from the valve assemblies llOi, HOii through the delivery valve 12 Oi, 12 Oil. During inflow of fluid through the suction valves 115i, 115ii, the delivery valves 120i, 120ii need to remain closed and sealed up. During inflow, the delivery valve balls 1211, 121ii are forced through pressure and / or gravity into their respective delivery valve seats 124i, 124ii, maintaining a seal on the delivery valves 120i, 12Oii. The pump 100 further comprises a piston 125 located centrally between the two valve assemblies llOi, llOii. The piston 125 reciprocally moves from side to side between the two valve assemblies 11 Oi, llOii. The piston 125 is connected to a shaft 127 which extends in both directions away from the piston 125 towards the two valve assemblies llOi, llOii. Each end of the shaft 127 is connected to a rigid plate 130i, 130ii. The rigid plates 130i, 130ii on each side of the shaft 127 are designed to draw fluid into / expel fluid out of the valve assemblies llOi, llOii during operation. When the piston 125 moves towards valve assembly 1101, rigid plate 130i is expelling fluid from valve assembly llOi, and rigid plate 13Oii is drawing fluid into valve assembly llOii. Likewise, when the piston 125 moves away from valve assembly llOi, rigid plate 130i is drawing fluid into valve assembly 1 lOi, and rigid plate 130ii is expelling fluid out of valve assembly llOii. The reciprocal motion of the piston 125 connected to the rigid plates 130i, 130ii via the shaft 127 means one of the valve assemblies llOi, llOii will be drawing fluid into itself through its respective suction valve 115i, 115ii, whilst the other valve assembly llOi, llOii will be expelling fluid out of itself through its respective deliveiy valve 12 Oi, 12 Oii. The pump 100 further comprises flexible seals 135i, 135ii. The flexible seals 135i, 135ii are fixed to the rigid plates 130i, 130ii, creating a seal between the fluid being drawn into / expelled out of the valve assemblies 115i, 115ii and the space which the piston 125 and shaft 127 occupy. The flexible seals 135i, 135ii are designed to flex during the reciprocal motion of the piston 125 and the rigid plates 130i, 130ii. Figure la shows the pump 100 during operation wherein the piston 125 is at a fully extended position towards the second valve assembly 115ii and away from the first valve assembly 115i. In this instance the second valve assembly 115ii has just expelled fluid through its delivery valve 12Oil The delivery valve ball 121ii is sitting in its open configuration in its delivery valve cage 122ii, allowing fluid to pass through the delivery valve 120ii. The suction valve ball 116ii is sitting in its closed configuration in its suction valve seat 119ii, creating a seal that stops any fluid from passing through the suction valve 115ii. Furthermore, at the same time, the first valve assembly 115i has just drawn fluid through its suction valve 115i. The suction valve ball 116i is sitting in its suction valve cage 117i, allowing fluid to pass through the suction valve 115i. The delivery valve ball 12Oi is sitting in its delivery valve seat 124i, creating a seal that stops any fluid from passing through the delivery valve 1201 Figure lb shows the pump 100 directly after its position in Figure la. In Figure lb, the piston 125 moves away from the second valve assembly 115ii towards the first valve assembly 115i. The movement of the piston 125 decreases the pressure in the second valve assembly HOii drawing fluid into the second valve assembly HOii through the suction valve 115ii. At this instance, the suction valve ball 116ii is sitting in its open configuration in its suction valve cage 117ii, allowing fluid to flow through the suction valve 115ii. At the same time, the delivery valve ball 12lii is sitting in its closed configuration in its delivery valve seat 124ii, creating a seal at the delivery valve 120ii, ensuring that no fluid escapes. At the same time, whilst fluid is being drawn into the second valve assembly 1 lOii, fluid is being expelled out of the first valve assembly 1101. The piston 125 moving towards the first valve assembly llOi reduces the volume available for fluid and increases the pressure in the first valve assembly 11 Oi, causing fluid to be expelled through the delivery valve 120i. The suction valve 115i is in a closed configuration and the delivery valve 120i is in an open configuration. The suction valve ball 116i is sitting in its suction valve seat 119i, creating a seal at the suction valve 116i, ensuring that no fluid escapes. The delivery valve ball 12li is sitting in its delivery valve cage 1221, allowing fluid to exit through the delivery valve 120i. Figure lc shows the pump 100 directly after its position in Figure lb. In Figure lb, the piston 125 is at a fully extended position towards the first valve assembly 115i and away from the second valve assembly 11511. In this instance the first valve assembly 115i has just expelled fluid through its delivery valve 120i. The deliveiy valve ball 12li is sitting in its open configuration in its delivery valve cage 12 2i, allowing fluid to pass through the delivery valve 1201 The suction valve ball 116i is sitting in its closed configuration in its suction valve seat 119i, creating a seal that stops any fluid from passing through the suction valve 1151 Furthermore, at the same time, the second valve assembly 115ii has just drawn fluid through its suction valve llSii. The suction valve ball 116ii is sitting in its open configuration in its suction valve cage 117ii, allowing fluid to pass through the suction valve 115ii. The delivery valve ball 120ii is sitting in its closed configuration in its delivery valve seat 124ii, creating a seal that stops any fluid from passing through the delivery valve 120ii. This reciprocating process continues, constantly drawings fluid through the suction valves 115i, 115ii and expelling it through the delivery valves 120i, 120ii. Turning now to Figure 2, there is shown a side view of the valve assembly 11 Oi, llOii. The suction valves 115i, llSii are located upstream of the delivery valves 120i, 120ii. The valve assemblies 11 Oi, llOii are located on either side of the pump 100. Turning now to Figure 3, there is shown a perspective blown-up view of the components of the valve assembly llOi, llOii. The first and second valve assemblies llOi, llOii are identical. Each valve assembly comprises a suction valve 115i, llSii and a delivery valve 120i, 120ii. The suction valve 115i, 115ii comprises a suction valve ball 116i, 116ii, a suction valve cage 1171, 117ii, and a suction valve seat 119i, 119ii. The delivery valve 1201, 12011 comprises a delivery valve ball 12 li, 12lii, a deliveiy valve cage 122i, 122ii, and a delivery valve seat 124i, 124ii. Furthermore, the suction valve 115i, llSii also comprises a threaded end piece 130i, 130ii which holds all of the suction valve components in place during operation. The threaded end piece 130i, 130ii is connectable to a fluid source such that fluid can be drawn into the valve assemblies 1 lOi, llOii. Likewise, the delivery valve 120i, 120ii comprises a threaded end piece 135i, 135ii. The threaded end piece 135i, 135ii is connectable to a fluid outlet such that fluid can be pumped out of the valve assemblies llOi, 1 lOii. The pump 100 defines a cavity 150 which houses the piston 125. During operation, the piston is reciprocally moved between a fully extended position on the right (as shown in Figure la) of the cavity 150 and a fully extended position on the left (as shown in Figure lc) of the cavity 150. The pump 100 further comprises a first aperture 160 and a second aperture 165, and a shuttle assembly 170. The shuttle assembly 170 comprises a pilot air valve 171. The reciprocal motion of the piston 125 is caused by alternating the direction of the flow of gas being injected into the cavity 150 through the first and second apertures 160,165. As the direction of gas flow is changed, the piston 125 moves from side to side within the cavity 150, allowing the valve assemblies llOi, HOii to pump liquid. Likewise, the movement of the piston 125 from side to side pushes liquid and / or gas out of first and second drainage ports 181, 186. This results in liquid and gas mixture being alternately drained from the cavity 150 through the first and second drainage ports 181,186 out of the cavity. Once the gas and / or liquid is drained from the first and second drainage ports 181,186, the gas and / or liquid is pushed through a filter and the liquid portion is separated from the gas portion. The gas portion is then recycled back into the shuttle assembly 170 through one of the first or second apertures 160,165 and injected back into the cavity 150 through either one of the first and second apertures 160, 165. The liquid portion is discarded. Recycling the gas portion ensures that there is no pressure loss within the shuttle assembly 170 and cavity 150, resulting in improved efficiency. The reciprocal motion of the piston 125 is controlled by alternating which one of the first and second apertures 160, 165 the gas is injected into the cavity 150 through. This is controlled by the shuttle assembly 170 and the pilot air valve 171. The pilot air valve 171 is moved between a left configuration and a right configuration. When in its left configuration, the pilot air valve 171 creates a direct flow path between the pressurized gas inlet and the first aperture 160. Likewise, when in its left configuration, the pilot air valve 171 creates a direct flow path between the second aperture 165 and a gas exhaust. The left configuration of the pilot air valve 171 permits gas to enter the cavity 150 through the first aperture 160, pushing the piston 125 towards the right side of the cavity 150. As the right side of the cavity 150 is now in a direct flow path with the gas exhaust, it is no longer under pressure, and, therefore, the force of the piston 125 being pushed towards the right side of the cavity 150 forces the gas out of the second aperture 165 and the second drainage port 186. Once the piston 125 has reached its fully extended position towards the right side of the cavity 150, the piston 125 contacts a first exhaustvalve pin (not shown). This contact opens up a flow path for the gas within the cavity 150 back towards the pilot air valve 171. Pressurized gas now travels back towards the pilot air valve 171, causing it to displace to its right position. When the pilot air valve 171 is in its right position, a direct flow path is created between the pressurized gas inlet and the second aperture 165. Likewise, when in its right configuration, the pilot air valve 171 creates a direct flow path between the first aperture 160 and the gas exhaust. The right configuration of the pilot air valve 171 permits gas to enter the cavity 150 through the second aperture 165, pushing the piston 125 towards the leftside of the cavity 150. As the left side of the cavity 150 is now in a direct flow path with the gas exhaust, it is no longer under pressure, and, therefore, the force of the piston 125 being pushed towards the left side of the cavity 150 forces the gas out of the first aperture 160 and the first drainage port 181. Once the piston 125 has reached its fully extended position towards the left side of the cavity 150, the piston 125 contacts a second exhaust valve pin (not shown). This contact opens up a flow path for the gas within the cavity 150 to travel back towards the pilot air valve 171. Pressurized gas now travels back towards the pilot air valve 171, causing it to displace to its left position. The gas exiting the pilot air valve 171 through the gas exhaust is then passed through an air regulator permitting the gas to be recycled and reused. Alternatively, the gas exiting the gas exhaust is vented to the atmosphere and new gas is brought in to create the reciprocal movement of the piston 125. Alternatively, the gas exhaust is valve actuated creating a controlled pressurized environment with the pump 100. It will be appreciated that other methods of controlling gas flow between the gas inlet and the cavity may be used. Different configurations of the pilot air valve may be used. During exhaustion of gas from either side of the cavity 150, gas and / or liquid is forced through either the first or second drainage ports 181,186. The gas portion of the exhausted gas and / or liquid exhausted through the first drainage port 181 is in fluid connection with the first aperture 160 through a passage 161 (as shown in Figure lb) on the side of the first aperture 160. The gas portion exhausted out of the first drainage port 181 is exhausted out of the cavity at the same time as the gas exhausted through the first aperture 160. The fluid connection between the first drainage port 181 and the first aperture 160 ensures pressure is maintained between all the gas and / or liquid on the left side of the piston 125 at any given time. Likewise, the gas portion of the exhausted gas and / or liquid exhausted through the second drainage port 186 is in fluid connection with the second aperture 165 through a passage 166 (as shown in Figure lb) on the side of the second aperture 165. The gas portion exhausted out of the second drainage port 186 is exhausted out of the cavity at the same time as the gas exhausted through the second aperture 165. The fluid connection between the second drainage port 186 and the second aperture 165 ensures pressure is maintained between all the gas and / or liquid on the right side of the piston 125 at any given time. Although particular embodiments of the disclosure have been disclosed herein in detail, this has been done by way of example and for the purposes of illustration only. The aforementioned embodiments are not intended to be limiting with respect to the scope of the summary / appended claims. It is contemplated by the inventors that various substitutions, alterations, and modifications may be made to the invention without departing from the scope of the invention as defined by the summary / claims.

Claims

1. A positive displacement pump for pumping a fluid, the pump comprising a valve assembly comprising a pressure responsive suction valve and a pressure responsive delivery valve, the suction valve and the delivery valve each being moveable between a respective open configuration and a respective closed configuration such that flow of fluid through the valve assembly is unidirectional.

2. A positive displacement pump according to Claim 1, wherein the positive displacement pump has a preferred operating orientation relative to gravity.

3. A positive displacement pump according to Claim 2, wherein the suction valve and / or the delivery valve are gravity responsive.

4. A positive displacement pump according to Claim 3, wherein when the pump is in its preferred operating orientation relative to gravity, the suction valve and / or the delivery valve are forced towards their respective closed configurations by gravity.

5. A positive displacement pump according to any preceding Claim, wherein the suction valve and / or the delivery valve are openable by pressure.

6. A positive displacement pump according to any preceding Claim, wherein the suction valve and / or the delivery valve are closable by pressure.

7. A positive displacement pump according to any preceding claim, wherein the suction valve and / or the delivery valve comprise a ball and cage valve.

8. A positive displacement pump according to any preceding claim, wherein the pump is a reciprocating positive displacement pump comprising a piston.

9. A positive displacement pump according to claim 8, wherein the piston comprises a rigid plate and a flexible seal.

10. A positive displacement pump according to any preceding claim, wherein the pump is a double acting positive displacement pump comprising two valve assemblies.

11. A method for pumping a fluid, the method comprising:using a positive displacement pump comprising a valve assembly comprising a pressure responsive suction valve and a pressure responsive delivery valve;the method further comprising increasing the pressure in the valve assembly;the pressure increase causing the delivery valve to open into an open configuration and the pressure increase causing the suction valve to close into a closed configuration such that fluid exits the valve assembly via the delivery valve; andthe method further comprising decreasing the pressure in the valve assembly;the pressure decrease causing the delivery valve to close into a closed configuration and the pressure decrease causing the suction valve to open into an open configuration such that fluid enters the valve assembly via the suction valve.

12. A method for pumping a fluid according to Claim 11, wherein the positive displacement pump has a preferred operating orientation relative to gravity.

13. A method for pumping a fluid according to Claim 11 or Claim 12, wherein the suction valve and / or the delivery valve are gravity responsive, and wherein the gravity responsiveness results in the or each valve being forced towards their respective closed configurations by gravity when pump is in its preferred operating orientation relative to gravity.

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