The present invention relates to filtration equipment, and in particular, the present invention relates to a purification system that includes a single stage filter and a means to perform a filter integrity test on this filter.
Various medical equipment, such as medical device reprocessing equipment, requires the use of purified water meeting certain levels of water quality. In particular, levels of bacteria, viruses, and endotoxins are of critical importance as these represent significant hazards to patients that are connected to or using devices that have been prepared with this equipment. As a result, purification of fluids used by or entering the equipment is of an utmost necessity. Filtration, and in particular ultrafiltration, is a common purification method to remove these microbiological contaminants from water before it is introduced into a certain piece of equipment. One way to assure sufficient quality of water feeding this equipment, is to use two filters in series, whereby if one filter were to lose its integrity (e.g. if there is a breach in the filter membrane), the other filter serves as a back-up.
As a back-up filter, contaminates are removed before the water is introduced to the equipment, thus rendering the water safe for use. Use of two filters in series, or a single filter with dual stages, however, is generally costly. In addition, these dual-filter systems typically result in lower flow rates as there is an added pressure drop caused by the second, redundant filter. It is also known in the art, that a single stage filter can be used, provided it has been tested to insure the membrane is intact. These tests are commonly called filter integrity tests and generally use pressurized air (or other suitable gas) as a means to verify membrane integrity. However, when water is purified before it enters a piece of equipment, such as by installing a water filter in the line feeding the equipment, there is no way to perform these integrity tests without possibly interrupting the flow of water to the piece of equipment. If this occurs when the equipment is commanding water, problems or errors will likely occur as the equipment may no longer function correctly. It is generally understood that this equipment performs automated functions and that water is used for discrete intervals of time (as opposed to using water on a continuous basis).
There is therefore a need for a system that allows for a filter integrity test to be performed such that it does not adversely effect the operation of the downstream equipment.
In accordance with the present invention and in view of overcoming the disadvantages associated with the conventional devices, a purification system includes a single stage filter and a means to perform a filter integrity test on this filter, whereby the purification system is able to detect when water is being used by the downstream equipment and thereby coordinate when a filter integrity test is to be performed that does not adversely effect the operation of the downstream equipment. In addition, the system permits a flushing of the upstream filter compartment to remove accumulated particulate from the source water which can increase the life of the filter. With the water purification system of the present invention, the filter flush steps can also be coordinated so as not to interfere with the operation of the downstream equipment. For example, the filter is flushed only when no water is being commanded by the downstream equipment.
In accordance with another embodiment, a method for performing a filter integrity test in a liquid purification system that is configured to purify a liquid from a liquid source using a filter device and deliver the purified liquid to external downstream equipment, includes the steps of: (1) monitoring when the external downstream equipment is receiving and using purified liquid from the filter device; and (2) initiating the filter integrity test only when the external downstream equipment is not commanding purified liquid.
As shown in
The housing includes a first header cap 240 that is coupled to the first end 202 of the housing 230 and a second header cap 242 that is coupled to the second end 204 of the housing 230. Typically, the first and second header caps 240, 242 are removably (detachably) coupled to the housing 230. The first header cap 240 defines a first header space 244 that is formed between the first header cap 240 and the open ends of the semi-permeable membranes 235 and first potting compound 231. Similarly, the second header cap 242 defines a second header space 246 that is formed between the second header cap 242 and the opposite open ends of the semi-permeable membranes 235 and second potting compound 232.
The first header cap 240 includes a port that provides communication with the first header space 244 and thus, provides fluid communication with the semi-permeable membranes 235. In the illustrated embodiment, the port is in the form of inlet 210 since it permits fluid (from the source 110) to enter the first header space 244. Similarly, the second header cap 242 includes a port that communicated with the second header space 246 and thus, provides fluid communication with the semi-permeable membranes 235. This port is in the form of outlet 220 since it permits liquid to flow out of the housing.
While the filtering media has been described as a plurality of semi-permeable membranes (fibers), it will be appreciated that it can take other forms that suitable for the disclosed filter applications. In addition, the housing can have any number of different shapes.
It will also be appreciated that within the housing, there is a space between the inner surface of the housing and the semi-permeable membranes 235.
At the outlet 220, there is a third connector 250 (
The housing also includes a third port 260 that is located along a side thereof and communicates within an interior of the housing and in particular, is in communication with the space surrounding the semi-permeable membranes 235. In the illustrated arrangement, the third port 260 attaches to a fourth connector 270 (
The external device 300 includes a valve 301 that can be operated between an open position where fluid flows into the external device 300 and a closed position where fluid is prevented from flowing to the external device 300. The valve 301 is thus in fluid communication with the output conduit 280.
The purification system 100 includes a number of components that are configured to test the integrity of the filter device 200 in a manner that overcomes the disadvantages associated with conventional integrity test systems as described above.
In one embodiment, the system 100 includes an air input component 400 that is designed to introduce ambient air, at a selected time, into the filter device 200. More specifically, the air input component 400 serves to introduce ambient air into the interior of the filter device 200 and more particularly, into the hollow lumens of the semi-permeable membranes 235. The air is delivered from a source (e.g. atmosphere) and is delivered to the filter device 200 through a conduit 402 and by means of a pump 410 or the like. Along the conduit 402, a second valve 420 is provided and can be operated between an open position where air is delivered to the filter device 200 and a closed position. The second valve 420 is in communication with the controller 105.
In accordance with the present invention, a device 500 is provided for detecting and sensing pressure. More particularly, the device 500 is in the form of a differential pressure sensor (transducer) that measures the difference between two pressures introduced as inputs to a sensing unit that is part of the device 500. In the present embodiment, the pressure sensing device 500 can be used to measure the pressure differential across the filter media (i.e., semi-permeable membranes 235). For example, the pressure within the semi-permeable membranes 235 (inside the lumens) can be sensed and compared to an external pressure (outside the semi-permeable membranes 235). For example and as described below, the pressure sensing device 500 can be operatively connected to the device 200 to sense the pressure within the semi-permeable membranes 235 and the pressure within the output conduit or line 280 (e.g., of the output liquid downstream of the filter). In this manner, the pressure differential across the filter media (semi-permeable membranes 235) can be determined.
The purification system 100 includes a mechanism for flushing the filter device 200 and in particular, the filter device 200 can include a flush device 600 that includes a flush conduit or line 610. The flush conduit 610 is in fluid communication with a drain or waste 700 to permit the fluid that is used to flush the filter device 200 to be disposed of. Along the flush conduit 610, a third valve 620 is provided. The third valve 620 is operational between an open position where the fluid is delivered to the drain or waste 700 and a closed position. The third valve 620 is in communication with the controller 105.
The purification system 100 also includes a vent line or conduit 800. The vent line 800 includes a first end 802 and a second end 804 with the first end 802 being in fluid communication with the output conduit 280 and in particular, the first end 802 of the vent line 800 is located proximate the fourth connector 270. The second end 804 of the vent line 800 is in communication with the flush conduit 610 at a location downstream of the third valve 620. The vent line 800 is thus in fluid communication with the drain or waste 700. Along the vent line 800, a fourth valve 810 is provided. The fourth valve 810 is operational between an open position where the fluid is delivered to the drain or waste 700 and a closed position. The fourth valve 810 is in communication with the controller 105.
As shown in the figures, the drain or waste 700 can be fluidly connected to another conduit that delivers waste fluid to the waste 700. For example, a waste or drain line 900 that is associated with the external device 300 delivers waste fluid to the drain or waste 700. A tee connector 1000 can be provided for linking the flush conduit 610 and the drain line 900 with the drain or waste 700.
In addition with one aspect of the present invention, a device 1100 for displaying an integrity status signal can be provided. The device 1100 can display different information and indicia for indicating the operating status of the purification system 100. For example, the device 1100 can display an indicator that the filter (filter device 200) passed the integrity test and an indicator that the filter failed the integrity test. For example, the word “PASS” or “FAIL” can be displayed or a green light can be displayed when the filter passes and a red light can be displayed when the filter fails.
In addition, a user interface 1200 can be provided and includes a display 1210, a first button 1220 and a second button 1230. The user interface 1200 may allow the user to set various parameters associated with its operation for a particular type of equipment. The display 1210 can be a single line display showing the filtration process step as described below.
It also should be understood that the water purification system 100 can include buttons, such as buttons 1220, 1230 to reset the summed number of “Fill” or “Use” operations at any point in time such that is stays coordinated with the downstream equipment operations. An additional Button may also be included to allow the user to replace the filter without shutting off the source water and perform an automated priming routine (not shown). For example, the button 1220 can be a filter “install” button and upon actuation, results in the closing of the first valve 140 and allows one to install a new filter 200 and then prime the filter 200. The button 1230 can be a reset “fill counter” button to provide a means for the purification system 100 to be in sync. with the start of the reprocessing equipment cycle.
In accordance with the present invention, the purification system 100 is configured using a single stage filter (filter device 200) and a means to perform a filter integrity test on this filter, whereby the purification system 100 is able to detect when water is being used by the downstream equipment and thereby coordinate when a filter integrity test is to be performed that does not adversely affect the operation of the downstream equipment. In addition, a flushing of the upstream filter compartment to remove accumulated particulate from the source water is used to increase the life of the filter. With the water purification system 100 of the present invention, the filter flush steps can also be coordinated so as not to interfere with the operation of the downstream equipment 300. For example, the filter (filter device 200) can be flushed only when no water is being commanded by the downstream equipment 300.
In accordance with the present invention, there are a number of operating modes of the purification system 100 as described below and as illustrated in
The valves 420, 620, 810 are closed in this operating mode.
In this operating mode the purification system 100 is in an IDLE state and the device 1100 can display positive information regarding the operating state.
As shown, the fluid (water) is filtered by flowing from the source 110 into the filter device 200 and is then filtered across the semi-permeable membranes 235 to generate purified liquid that is flows out through the third port 260 into the output conduit 280 to the external device 300. The valves 420, 620, 810 are closed in this operating mode.
In this embodiment, the water that does filter across the membrane 235 flows out of the third port 260 and flows along conduits 800 and 610 to the drain 700 since the vent valve 810 is open.
Since air cannot cross an intact membrane, the air pressure on the inlet side of the membrane will increase. Upon reaching a specified level as measured by the differential pressure transducer 500, the air pump 410 is stopped and the air valve 420 is closed.
Upon passing the integrity test, the “fill” or “use” counter may be reset to zero and the system 100 may be put into its standard operating mode as described above. Upon failing the integrity test, the inlet valve 140 may be kept closed to prevent any subsequent passage of water to the downstream equipment 300. An optional red status light (display 1100) can be illuminated to alert the user that the filter 200 failed and must be replaced. Upon replacing the filter 200, the user can repeat the cycle performed by the downstream equipment. This assures that only good purified liquid (water) from an intact filter is delivered to the downstream equipment 300.
When the downstream equipment 300 is in an IDLE period with respect to the fluid (water) feed, the pressure differential will be zero. Provided this is true, the flush valve 620 may be open for a specified period of time to flush accumulated particulate from the upstream side of the filter 200. This has the effect of increasing the useful life of the filter before it becomes too fouled to produce a sufficient quantity of water for the downstream equipment. One will appreciate that the flush operation can be programmed to occur at a set frequency or it can be tied to a set number of “fill” or “use” operations that have been detected.
At the end of the flush period, the flush valve 620 is closed and the system 100 is placed back in the standard operating mode as described herein.
Other features and advantages of the system 100 include but are not limited to the following: (1) by tracking the differential pressure (Pdiff) over time when water is being delivered to the downstream equipment, one can set a specified level at which may indicate the filter is sufficiently “fouled” and should be replaced; (2) a separate signal (such as an electrical signal) can be generated by the system and sent to the downstream equipment 300 which can be used to determine the status of water purification unit 100, e.g. the signal could be different when the filter has FAILED an integrity test—this signal can be used to alert the user of the downstream equipment that there is a problem with the water purification unit; (3) different mechanisms that are known in the art can be used to detect when the water is being commanded by the downstream equipment 300. For example, a flow detector or flow switch can be used to detect the flowing condition; and (4) it will be appreciated that different methods that are known in the art can be used to test filter integrity—this can include an air bubble detection unit on the downstream side of the filter as a Bubble-point type measurement, or an Air Flow test whereby the flow rate of air is measured which is needed to maintain a constant pressure in the upstream compartment.
It will also be appreciated that the flow configuration described and illustrated herein is one of many configurations that can be used. The illustrated configuration is presented as it minimizes the components in the feed stream to the downstream equipment and thereby keeps the flow of water to the downstream equipment at a maximum level (i.e. no additional flow resistances).
While the invention has been described in connection with certain embodiments thereof, the invention is capable of being practiced in other forms and using other materials and structures. Accordingly, the invention is defined by the recitations in the claims appended hereto and equivalents thereof.
This application claims the benefit of U.S. Patent Application Ser. No. 61/285,292, filed Dec. 10, 2009, which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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61285292 | Dec 2009 | US |