LABORATORY FILTRATION APPARATUS

Abstract: A laboratory filtration apparatus is described in which flow through the filter is measured as the filter is being used and then visually displaying an indication of the measured flow which is used to indicate the effectiveness of the filter. In one arrangement air and water are filtered using separate filters (24, 36) and the effectiveness of the filter is monitored by using flowmeters (28, 30) coupled to microprocessor-based control systems (34) and the output of the microprocessor-based control system is coupled to a visual display unit (32) which gives separate visual indication of the effectiveness of air and the water filter.

Description: LABORATORY FILTRATION APPARATUS The present invention relates to filtration apparatus particularly, but not exclusively, for use in laboratories for filtering air and water to be used in laboratory experiments. It is known to filter air and water for use in the laboratory to give a source of clean air and water for use in experiments. This is usually done by placing a filter in line with the outlet so that the air or water supply to the laboratory is passed through the filter and is thus cleaned. With this system there is no indication of the performance of the filter nor when the filter is ceasing to be effective. Accordingly filters are changed after an arbitrary time and this, of course, can vary depending on the use of the filter and on how clean the air or water supply to the filter is. The result of this arbitrary replacement is that the air and water supply to the laboratory is less clean than it should be because there is no indication of filter performance nor of when the filter requires to be changed. An object of the present invention is to provide an improved filtration apparatus which obviates or mitigates at least one of the aforementioned disadvantages. This is achieved by measuring flow through the filter as the medium, such as air or water, is being used and visually displaying the flow through the filter to a use to provide a visual indication of the effectiveness of the filter. In a preferred arrangement air and water are filtered using separate filters and the effectiveness of the filter is monitored by using flowmeters coupled to microprocessor-based control systems and the output of the microprocessor-based control system is coupled to a visual display unit which gives separate visual indications of the effectiveness of air and the water filter. Conveniently the air and the water supply have an inline pump or valve means and the pressure in the filter system is monitored and the monitored pressures are coupled to a second microprocessor based control means such that should the pressures in either filter exceed or fall beneath a predetermined value then a signal is sent from the second microprocessor base means to actuate the valve or pump means to interrupt the water supply. With this arrangement the user actuates the water supply by turning on a tap, the water passes through a flow meter and filter before being dispensed from the tap nozzle. The flow of water is monitored by the microprocessor and the result is displayed on a L.E.D. display in analogue form. For a particular flow rate the analogue display will depict a particular value, however, should the filter become blocked or clogged up then this value falls the operator will see that there are problems with the filtration and accordingly can switch the system off and replace the filter. Alternatively the system can be configured so that for a particular flow rate if the signal drops beneath a predetermined value the microprocessor can switch the water supply by means of a valve to pass through a further filter so that the original filter can be changed. This can be applied to the air supply as well as to the water supply. Accordingly in one aspect of the present invention there is provided apparatus for determining the effectiveness of a filter coupled in line to a supply of a medium such as air or water, said apparatus comprising; a flowmeter in an inlet line to a filter, said flow meter having an output coupled to a control means said control means having an output coupled to a visual display, the arrangement being such that when said medium outlet is switched on the level of display indicates the effectiveness of the filter and for a particular flow rate should this drop then a visual indication is provided that the filter requires to be changed. Preferably the visual display is an analogue display although it will be appreciated this may be a digital display. Conveniently the control means is a microprocessor based system for monitoring the flow in both water and the air or any medium requiring filtration and processing this information to be passed to the display element, the display element having a separate display associated with each filter so that the filtration performance of each filter can be separately monitored. Conveniently the pressure of fluid through the filter can be monitored using a separate microprocessor based control system the output of which is coupled to valve or pump means for supplying the air or water to the appropriate filter so that in the event of over pressure or under pressure outwith certain limits the microprocessor can disconnect the air or water supply. The output of the filter may be coupled to a deioniser column or any other device which requires a supply of filtered water. The air filter includes a purge valve and this can also be actuated automatically using the microprocessor-based control system. In another aspect of the present invention there is provided a method for indicating the condition of a filter, said method comprising the steps of monitoring the flow of a medium through the filter, processing the monitored flow value to provide a signal representative of a particular flow, and visually displaying this signal on a visual unit to a user so that the performance of the filter can be monitored. Preferably if the signal for a particular flow rate drops beneath a predetermined value the medium being filtered is automatically rerouted to a second filter and is indicative that the original filter requires to be changed or cleaned. These and other aspects of the present invention will become apparent from the following description when taken in combination with the accompanying drawings in which:- Fig. 1 is a perspective view of a laboratory bench incorporating laboratory filtration apparatus in accordance with an embodiment of the present invention, and Fig. 2 is a schematic diagram of the apparatus as shown in Fig. 1. Reference is first made to Fig. 1 of the drawings which shows a typical laboratory bench,generally indicated by reference numeral 10, for supplying filtered air and water through tap 12 and air outlet 14 respectively. A deioniser 16 is also shown and this supplies deionised filtered water to the laboratory. As will be explained air and water supplies 18, 20 are disposed beneath the bench top 22 and the inlets are passed through respective air and water filters 24, 26 the outlets of which are connected to the air outlet 14 and to the tap 12 and deioniser 16 respectively. In line with the filter supply are flow meters 28 and 30 which are coupled to a microprocessor-based control unit (not shown in the interest of clarity) the output of which is coupled to a visual display unit 32 which has separate visual display elements associated with the air and water filters respectively so as to indicate the performance or condition of each filter in operation, as will be later explained in detail. Reference is now made to Fig. 2 of the drawings which depicts a schematic diagram of the laboratory filtration system shown in Fig. 1. From this diagram it can b e seen that flow meters 28 and 30 are connected to a first micro ¬ processor 34 which has outputs 36, 38 which are fed to a first LED display element 40 for indicating the condition of the air filter 24 and to a second LED display element 42 for indicating the condition of the water filter 26. A further flow meter 44 connected between the input of filter 26 and the inlet to the deioniser can also b e coupled to the microprocessor unit and the effectiveness of the deioniser can also be shown on a separate disp l ay. The microprocessor 34 is configured and programmed in accordance with known techniques to drive displays 40 an d 42. In operation, when a user turns on the tap 12 water flows through flow meter 30 and through filter 26 out of the tap. The flow meter 30 provides a signal which is processed by the microprocessor 34 to drive display 42 so that the number of elements illuminated is indicative of the performance of the filter for that particular flow rate. If the flow rate is always set at maximum then all of the light emitting diodes will illuminate and as long as the filter stays clear and is effective then all of these diodes should remain illuminated. Should the filter performance degrade because it requires changing or there is some blockage then the number of illuminated LEDs in display 42 will decrease and this is indicative that the filter performance is decreasing and that the filter requires changing. The display 40 and associated microprocessor 34 operates in the same way to visually depict the performance and condition of air filter 24. Thus a user can readily and easily monitor the performance of the filters and when they require to be changed using this system. In Fig. 2 there is also shown pressure sensors 46, 48 associated with the air filter 24 and water filter 26 respectively. These pressure sensors have outputs connected to a second microprocessor 50 which in turn has outputs connected to a controlling element such as a valve or pump 52, 54 connected in line with the air and water supply 18 and 20 respectively. Pressure sensors 46 and 48 monitor the pressure in the filters 24, 26 respectively and the microprocessor compares these monitored pressure with predetermined values in, for example, look-up tables and should the pressure exceed or fall beneath the preset limits then the microprocessor can actuate the valve or pump to disconnect the air or water supply in the interests of safety if this is required. It will be appreciated that various modifications may be made to the apparatus hereinbefore described without departing from the scope of the invention. For example, it will be appreciated that although the display is an analogue display a digital display could be used although it will be appreciated that a separate display is required for each filter which is to be -monitored. Although a visual indication is given to the user that the filter requires to be changed so as to enable the user to change the filter, it will be appreciated that this may be done automatically by incorporating more than one filter for the air or water supply and for programming the microprocessor to switch to a second or subsequent filter when the performance falls beneath a predetermined value. This is conveniently combined with a separate display which indicates to the user that a subsequent filter is now in use and that the original filter requires to be cleaned or changed. It will also be appreciated that although air and water are the fluid media being filtered any other suitable laboratory media which requires filtration could be processed using this system such as special gases or special fluids. It will be appreciated that the filtration monitoring system can be used in an industrial scale as well as laboratory scale so as to provide a visual indication to the user of the effectiveness of the filter. An advantage of the present invention is that the user is immediately advised of the performance of the filter as it is being used so that the quality of the medium being supplied to the laboratory is able to be maintained by the user at the desired standard. A further advantage is that the system permits identification of filter performance in a rapid and convenient manner and requires no special skills to be able to interpret the information.

Claims: C AIMS 1. Apparatus for determining the effectiveness of a filter coupled in line to a supply of a medium such as air or water, said apparatus comprising; a flowmeter in an inlet line to a filter, said flow meter having an output coupled to a control means said control means having an output coupled to a visual display, the arrangement being such that when said medium outlet is switched on the level of display indicates the effectiveness of the filter and for a particular flow rate should this drop then a visual indication is provided that the filter requires to be changed. 2. Apparatus as claimed in claim 1 wherein the visual display is an analogue display or a digital display. 3. Apparatus as claimed in claim 1 or claim 2 wherein the control means is a microprocessor based system for monitoring the flow in both water and the air or any medium requiring filtration and processing this information to be passed to the display element, the display element having a separate display associated with each filter so that the filtration performance of ' each filter is separately monitored. 4. Apparatus as claimed in any preceding claim wherein the pressure of fluid through the filter can be monitored using a separate microprocessor based control system the output of which is coupled to valve or pump means for supplying the air or water to the appropriate filter so that in the event of over pressure or under pressure outwith certain limits the microprocessor issues a control signal to disconnect the air or water supply. 5. Apparatus as claimed in any preceding claim wherein the output of the filter is coupled to a deioniser column or any other similar device which requires a supply of filtered water. 6. Apparatus as claimed in any preceding claim wherein the air filter includes a purge valve which is actuated automatically using the microprocessor-based control system. 7. Apparatus as claimed in any preceding claim wherein a method for indicating the condition of a filter, said method comprising the steps of monitoring the flow of a medium through the filter, processing the monitored flow value to provide a signal representative of a particular flow, and visually displaying this signal on a visual unit to a user so that the performance of the filter can be monitored. 8. A method as claimed in claim 7 wherein if the signal for a particular flow rate drops beneath a predetermined value the medium being filtered is automatically rerouted to a second filter and is indicative that the original filter requires to be changed or cleaned.

Inventors: HOOD ROBERT GORDON, HOOD, ROBERT, GORDON
Applicants: BIO FLO LTD, BIO-FLO LIMITED
Application year: 1990
Main classification: B01D37
IPC codes: B01D35, B01D37