WO2020100171A1

WO2020100171A1 - Device for testing filter cartridges

Info

Publication number: WO2020100171A1
Application number: PCT/IT2019/000097
Authority: WO
Inventors: Claudio Guerra
Original assignee: Italfilter S.R.L.
Priority date: 2018-11-13
Filing date: 2019-11-12
Publication date: 2020-05-22
Also published as: IT201800010288A1; EP3880338A1

Abstract

A device for testing filter cartridges is disclosed which envisages the determination of the first bubble point characteristic of each filtering material and features a containment structure (2) divided into different sectors comprising a test chamber (20), sealed with doors (20a) to insulate the internal environment, a first technical chamber (21), located underneath the test chamber, which houses a tank (3) designed to contain a test fluid (4) and a second technical chamber located behind the other two chambers (20 and 21) and designed to house the components used to operate the said equipment. In particular, the device comprises a cartridge support unit comprising a horizontal guide (8) which accommodates a sliding, adjustable support (80) envisaged to support an anchoring element (9) for the cartridge (5), an air inlet element (10) located on the opposite side with respect to the anchoring element (9) and connected to a compressor and which adapts so as to enter any cartridge and a cartridge handling system, a pressure detection group consisting of two detection systems and management and control means (18) envisaged to manage, and drive the system's various units, systems, and components. Furthermore, the device comprises a filtering device (40) to ensure cleaning and prevent alterations and clogging in the cartridge (5) undergoing testing, a temperature control system (6) for the test fluid to keep the viscosity value constant for comparable test results, and a level control system (7) for the test fluid (4) in the tank (3).

Description

DEVICE FOR TESTING FILTER CARTRIDGES

Technical field

The present invention relates to a device for testing filter cartridges which is particularly suitable to have an instrument which, operating in a fully automatic manner, performs an inspection test to establish the integrity thereof and determine the first bubble point for filter cartridges.

Background Art

As is known, filter cartridges are used for filtering dry powders, mists, oily fumes, and chemical solvents and must be able to maintain good filtration efficiency for as long as possible for optimal use.

The materials mainly used to make the filter cartridges are cellulose, polyester, aluminised antistatic polyester, and metal.

In many case, filter cartridges feature a cylindrical shape and consist of a filtering media which is pleated to increase filtration efficiency by increasing the filtering surface area.

In addition, filter cartridges are also used to filter liquids and gases. These are filter elements composed of different materials and can be produced with different filtering media depending on the required application. The filtering media are specially processed according to needs in order to increase, for example, efficiency and resistance. Furthermore, the various filtering media can be coupled in multiple layers and pleated to achieve high levels of efficiency and storage capacity. Depending on the specifications and conditions of use, each cartridge is built with certain mechanical characteristics such as, for example, an internal support or an external protection mesh to increase the resistance thereof to differential pressure. The filtering degree of the filter cartridge is established based on the degree of cleanliness or purity of the fluid required by the system within which the filter cartridge will be fitted. Each filtering medium has its own filtration efficiency depending on the characteristics of the constituent material thereof.

Precisely because of the type of operation required of the cartridges, these must comply with clearly defined quality and resistance standards to prevent problems arising in the plants within which they are subsequently employed, with the result that, during the cartridge packaging process, tests are carried out on the components in order to prevent subsequent problems, i.e. whether the paper is compliant with specifications, whether the glue sealing the pleats holds fast, and whether the pleats have been bent properly.

Furthermore, to test whether the filter cartridge complies with filtration requirements, three tests are carried out: one at the beginning of production, one in the middle, and one upon completion of the production, for example, of a thousand filters. If higher production numbers are expected (e. g. 10,000 workpieces), more (up to ten) tests are performed.

At present, cartridge tests are performed manually by an operative, who dips a cartridge into a tray full of oil and injects air into the cartridge at a pressure of 9 mbar.

This operating procedure is known as the "first bubble test": if there are no air bubbles in the oil. this means everything is fine, i.e. the filter performs the task for which it was built, the materials and glues comply with specifications, and the components are assembled correctly.

If, instead a bubble comes out, the filter is not compliant and the operative carrying out the test will try' to see where the air is coming out, i.e. whether it is the glue on the base of the filter that is not gripping properly or whether the bubble is coming out of the paper, which means the paper is not the kind specified, as the injected air pressure is commensurate to the type of paper used and the level of filtration desired.

Under these conditions, production is stopped, everything is tested, and anything which is not compliant is replaced. As explained earlier, at present, the tests are performed manually and by one operative only, who is the only person who decides, based on the experience and ability thereof, on the validity of a filter cartridge.

Of course, the fact that it is a person who performs this delicate and important test can create problems due to the possibility of human error. Indeed, as the tests are repeated over many batches of different types of cartridges, there may be some oversights due to tiredness due to the repetitiveness of the procedure, due to the difficulty, at times, of seeing a bubble and understanding exactly where it comes from.

In addition to the explanations so far. there is legislation in force which requires three tests to be carried out, among which the ways in which the air is injected into the filter cartridge (filter) vary.

The first test requires the air pressure to be gradually increased from 0 to 9 mbar and the filter must perform two/three complete rotations so that the operative can see if there are bubbles anywhere on the surface thereof.

The second test involves increasing the air pressure in three steps: 3 mbar. 6 mbar, and 9 mbar and again the filter must make two rotations for each pressure value.

The third test requires the air pressure to increase quickly from 0 to 9 mbar and again the filter must make two rotations to check for bubbles.

In particular, the legislation requires that the filter be only partially immersed in the oil because the oil pressure could counteract the air inside the filter and stop the bubbles coming out.

As can be easily understood, there are various drawbacks linked to the procedures used to test the cartridges explained earlier. A first major drawback is the fact that the operative takes a long time to cam' out all the tests required, so there is a risk of downtime while awaiting the results or, alternatively, more personnel must be used, who are taken away from other processes, resulting in slowdowns in other sectors and costs due to the presence of more operatives.

Another drawback emerges from the fact that the test is performed manually by an operative who needs time and experience to acquire a well trained "eye", and be capable of detecting an air bubble coming from the cartridge undergoing tests. Furthermore, if the operative changes, the procedure, capacity, and precision change and certain aspects of the test parameters change, since they are subjective, not objective, as assessed by people. Furthermore it is a tiring, stressful activity due to the constant attention required to observe the behaviour of the cartridge, as the operative cannot be distracted even for a few seconds.

Nowadays, there is a great need felt for ever-better results in terms of precision and to alleviate the considerable effort of workers who, in the long run, lose their visual capacity, thus becoming less precise and slower, as well a need for standardised, automated tests.

Disclosure of Invention

The object of the present invention is essentially to solve the problems of the commonly known technique by overcoming the aforesaid difficulties by means of a device for testing filter cartridges capable of automatically performing the tests and evaluating the characteristics of the filtering material by determining the first bubble point and detecting any leaks in the finished cartridge with the integrity test.

A second object of the present invention is to provide a device for testing filter cartridges capable of storing the test and replicating the latter according to a coded test protocol for each kind of cartridge.

A third object of the present invention is to have a device for testing filter cartridges that can be easily adapted to any type, model, and size of cartridge to be tested. A further object of the present invention is to have a device for testing filter cartridges which is capable of automatically generating a report in electronic format for the traceability of the batch and the characteristics thereof.

Another object of the present invention is to have a device for testing filter cartridges which is capable of speeding up cartridge testing times, containing the costs of such tests, improving management of the production lots, and completely eliminating all inaccuracies and errors due to personnel.

A further object of the present invention is to have a device for testing filter cartridges which is capable of automatically replicating the determination of the first bubble point of the filtering media and providing a graph of the pressure values as a function of the time which is useful for testing the behaviour of different materials which feature coalescence characteristics.

A further, not final object of the present invention is to have a device for testing filter cartridges which is structurally simple, easy to maintain, as well as compact in size and very functional.

These objects and others besides, which will become apparent over the course of the present description, are essentially achieved by means of a device for testing filter cartridges as outlined in the claims below.

Brief Description of Drawings

Further characteristics and advantages will better emerge in the detailed description of a device for testing filter cartridges according to the present invention, provided in the form of a non-limiting example, with reference to the accompanying drawings, in which:

- Figure 1 shows, schematically, a front view of a device for testing filter cartridges according to the present invention;

- Figure 2 shows, schematically, the device in Figure 1 in the pre-testing condition;

Figure 3 shows, schematically, the device in Figure 1 in the testing condition; - Figure 4 shows, schematically, a detail of the device in question.

With reference to the aforesaid figures, and in particular Figure 1, 1 denotes, as a whole, the device for testing filter cartridges according to the present invention.

Best Mode for Carrying Out the Invention

To better understand how the device operates, the type of tests which must be performed to test compliance of the cartridge with that the requirements envisaged by legislation are explained below.

Legislation requires that the manufacturing integrity of a cartridge be tested by checking that there are no bubbles at a given pressure value (corresponding to the operating pressure) and locating the largest pore in the filtering material through the determination of the first bubble point. To be clearer, in the absence of manufacturing faults, the first bubble point is indicative of the largest pore present in the filtering material and this data is characteristic of the type material of which the cartridge filter element is composed.

The device for testing filter cartridges 1 in question is essentially composed of a containment structure 2 divided into different sectors comprising a test chamber 20 (where tests are performed on a cartridge), a first technical chamber 21, located underneath the test chamber which houses a tank 3 and a second technical chamber located behind the other two chambers 20 and 21, designed to house the components used to operate the said device.

In greater detail, the test chamber 20 is sealed by doors 20a, which insulate the internal environment so that it cannot be exposed to any kind of interference from the exterior during performance of the tests.

According to the present embodiment, the tank 3 is designed to contain a test fluid 4 which, in the majority of cases, is a paraffin-based oil which undergoes continuous filtration by a filtering device 40 composed of a hydraulic filter 40a controlled by a pump 40b in order to guarantee cleaning and prevent alterations and clogging in a test cartridge 5 and therefore incorrect feedback of the pressure value at which the first bubble appears, which is a specific characteristic of the filtering material used. In addition, in the filtering device 40 there is a tap 40c present, which is designed to discharge the test fluid 4 when particular maintenance operations have to be performed or the tank 3 has to be emptied. Indeed, it is particularly important to keep the test fluid 4 in suitable, optimal conditions in order to ensure correct results and render the results of the tests on the cartridges comparable.

Regarding this matter the device features a temperature control system 6 for the test fluid, in order to keep the viscosity value constant and therefore have comparable test results. To keep the viscosity constant, the test fluid 4 must have a temperature comprised within a predetermined range of values (22 ± 5) °C and therefore there is a coil 60 present, which is immersed in the tank, controlled by a pair of probes 61 and 62, and assigned to fluid heating. In particular, the second probe is designed to operate only if the first has problems and does not work. Indeed, if the temperature conditions are not met, the test is not started in any mode.

In the present embodiment, the device features a level control system 7 for the test fluid 4 in the tank 3, the said system comprising a sensor 7a which detects the fluid level in the tank and signals when a top-up thereof is needed and/or an automatic top-up is performed. Indeed, when the fluid level is too low with respect to the preset parameters, the system does not allow the test to be started. Moreover, a float 70 is featured, whose task is to signal overfilling and consequently stop a pump 71 designated to top up the fluid contained in a tank 72.

According to the present invention, the device features a cartridge support assembly comprising a horizontal guide 8 which houses a sliding and adjustable support 80 envisaged to support an anchoring element 9 for the cartridge 5. In greater detail and as shown in Figure 4, the anchoring element 9 features three pins 90, which move inside respective guides 90a to control the adjustment and movement of corresponding brackets 91 which open and close to house and constrain the cartridge 5, regardless of the diameter thereof. In particular, the support 80 which moves along the guide 8 allows a cartridge of any length to be positioned and constrained, while the anchoring element 9 constrains cartridges with different diameters. This way, the device can house and test different sized cartridges without any problems.

In addition to the explanations so far, on the side opposite the anchoring element 9 there is an air inlet element 10 connected to a compressor located in the second technical chamber. In particular, the element 10 is a silicone cone which adapts to fit into any cartridge, because it is both soft and has an increasing diameter.

In addition, the device features a chain 12, protected by a crankcase and driven by an electric motor 120. whose task is to move the cartridge and make it rotate around a shaft 120a which enters the cartridge, as shown in Figure 2.

In greater detail, the chain 12 is anchored to a support envisaged to move vertically along two guides located in the rear wall of the test chamber 20. The support is driven by a motor located in the second technical chamber.

Each movement is managed and controlled electronically by management and control means 18 to ensure the movement of the cartridge both when it is immersed and after the test, when the said cartridge is extracted from the tank 3. In particular, there is a hydraulic limit switch that prevents any vertical cartridge movement during the test, moreover, sensors are envisaged to guarantee the correct immersion of the cartridge and detect any vibrations of the said cartridge so that there are absolutely no vibrations when the tests are conducted.

According to the present invention, the device features a pressure detection unit consisting of two detection systems. The first system 13 is based on the principle of the U-shaped water column, which is placed on the rear wall of the test chamber 20 outside the tank, as shown in Figure 3.

The second pressure detection system 14 is located behind the test chamber in the second technical chamber and comprises pressure transmitters which detect the air parameters, converting them into numerical values. In this way, a digitally controlled electro-actuator obtains an output pressure within the ranges required to conduct the tests. In addition, the digital system is integrated into the management and control means 18, which manage it via dedicated software.

The device according to the present invention may operate in a semi-automatic manner, wherein an operator runs part of the operations, and in a totally automatic manner except for the positioning of the cartridge on the anchoring element (9), which is manual.

During operation in the event of non-compliance of some parameters with respect to those set, the said device signals, both visually and acoustically, an anomaly and interrupts the test procedure.

As stated earlier, the device operates with an electronically regulated pressure via an adjustment unit comprising a chain of electro-pneumatic components capable of obtaining micrometric pressure adjustments.

The absolute need to be able to measure the mbar originates from the need to determine the first bubble point exactly, since the said value is a characteristic of each filtering material. Even the slightest variation causes a considerable variation in the performance of the filtering media in terms of average pore size and therefore of actual filtration. Moreover, even the integrity test always works with these orders of magnitude, which are obviously smaller than the first bubble point.

Indeed, within the electro-pneumatic adjustment chain there are four vacuum valves featured which require protection via 5 pm (micron) absolute filtration. The four valves are located behind the test chamber in the second technical chamber. In greater detail, the first valve is envisaged to manage the data on the pressure gauges visible on a control panel 8 (as shown in Figure 2), the second manages the flow of air inside the cartridge, the third manages and feeds the air to the U-shaped column and, finally, the fourth manages the air output at the end of the test.

Given the very low test pressure levels involved, the entire pneumatic circuit must be hermetic as even a very slight air leak would jeopardise the reliability and value of the entire test.

Indeed, before beginning any testing on a cartridge, the said device is designed to perform, in an autonomous manner, a hermetic seal test, thus guaranteeing the absence of any incorrect reports of non-compliance of the cartridge.

The first hermetic seal testing step consists of the equalisation (by means of micrometric air release) of the pressure levels inside and outside the cartridge through the interaction of two of the electro-pneumatic valves present in the circuit. A stabilisation phase then follows, which depends on the type of cartridge/filter, as well as the size and characteristics. The time required for stabilisation is stated and filed away on the "recipe" (characteristics sheet) for the cartridge under examination, which is entered in the database of the device’s management and control system 18.

Once one of these is closed and all the other electro-pneumatic valves are open (which are managed and controlled electronically via a special software), the actual air injection begins.

The air injection continues until the set pressure value is reached via an electro-pneumatic regulator in series with a pressure regulator gauged to one tenth of a bar. The whole assembly is retrofitted with a digital pressure transmitter controlled with an electronic system, which constantly adjusts the pressure value, with a jogged system and algebraically, until the value set on the panel is reached and maintained. The automatic closing of the main valve, resulting in a hermetic condition, allows analysis of the cartridge as required by legislation.

The system displays all the data relating to pressure changes over time throughout the various steps of the test on the panel and also records it. Thus, the actual pressure trend is shown on the graph thereby allowing users to make visual comparisons of the behaviour of different filtering material under the same use conditions. This feature becomes a technical tool for comparisons based on the filtering material, the pressure, and the application time thereof.

The device management and control means 18 provide a report in electronic format with a graphical interface which states the test batch and date for each cartridge type in order to provide proper traceability in real time.

The device can replicate the test according to the values set on the control panel.

Once the preliminary steps have been carried out, the device can test the cartridge.

Before starting testing operations, the operative must take and position the cartridge to be tested, engaging it on the support by fitting one end into the air inlet cone 10 and the other onto the anchoring element 9 and then fastening the three pins loosened earlier so as to secure the end. Once the cartridge is in place, the doors of the containment structure 2 are closed so that nothing in the surrounding environment can interfere with the test chamber environment.

Through the management and control means 18 and the control panel 15, the operative enters an identification code specifying the filter type, which enables the device to recognise both the dimensional and the structural characteristics (paper type) of the filter. The data is entered into the memory beforehand so that the characteristics of many types of filters are available. At this point, the test of the cartridge can begin and therefore the cartridge is lowered until it is completely immersed and is kept immersed about 1.5 cm below the surface of the test fluid.

The cartridge is left immersed in the tank for a period of approximately 20-40 seconds to allow time for the fluid to enter the filter material of which the cartridge is comprised. During the period in which all the fibres of the cartridge are imbued, the device performs the hermetic seal test, to check that there are no leaks in the system’s electro-pneumatic circuit.

At this point, all the preparatory operations for the actual test are complete and the first test on the cartridge can begin.

Air is delivered by the compressor through the cone 10 into the filter with the pressure increasing from 0 to 9 mbar slowly and gradually and, in the meantime, the filter makes two rotations, driven by the belt 12

If everything is as it should be, the second test is then conducted, in which the air is injected into the cone 10 in three steps, at a pressure of 3 mbar, followed by 6 mbar, and finishing with 9 mbar; lastly the cartridge performs two rotations on itself again. There then follows the third test, in which the pressure is increased quickly from 0 to 9 mbar and the cartridge then also completes two full rotations around its axis.

If, during a test phase there is a bubble (recorded as an air leak from the solenoid valves), the device detects the pressure drop and signals the presence of an anomaly.

Each step of the test conducted is filmed by a camera and recorded so that, when the device signals an anomaly, the operative, by watching the video, can see exactly where the bubble has come from and establish whether the non-compliance is in the filtering material, in the glue on the bottoms or in the glue in the cartridge material joint, or somewhere else. At the end of the test, the cartridge rises out of the fluid and air is introduced to a preset pressure (approximately 1 bar) to release the fluid that had entered the filtering material earlier.

The operative releases the cartridge and inserts another one to test.

As mentioned earlier, the device records all the data relating to pressure variation over time from all the different steps in the test and displays this information on the management and control panel 15 in a graph showing the pressure trend and consequently the operator is able to graphically compare the behaviour of different filter materials under the same conditions of use, allowing technical comparisons based on the different parameters of the filtering materials.

The device according to the present invention is arranged to operate according to the following operating steps:

- the positioning of a cartridge on the cartridge support unit 8 and engagement with the air inlet element 10 and with the anchoring element 9,

- entry of a filter type identification code via the control panel, by an operator, for acknowledgement of the dimensional and structural characteristics of the filter,

- closure of the doors of the containment structure 2 so as to insulate the test chamber with respect to the surrounding environment,

- lowering of the cartridge into the tank 3 until the complete immersion thereof,

- priming of the cartridge filter material with the fluid 4 present in the tank,

first intake of air through the cone 10 in the filter with pressure increased from 0 to 9 mbar slowly and gradually, and performance of two complete rotations of the cartridge driven by the belt 12.

- second intake of air through the cone 10 in the filter in three steps, with pressure levels of 3 mbar. followed by 6 mbar, and finishing with 9 mbar, and performance of two complete rotations of the cartridge driven by the belt 12, - third intake of air through the cone 10 in the filter with pressure increased rapidly from 0 to 9 mbar. and performance of two complete rotations of the cartridge, provision of a report and a graph showing the pressure levels.

If there are anomalies, they are signalled to the operative, who can intervene.

While the cartridge undergoes the filtering material priming phase, the device performs a hermetic seal test to check that there are no leaks in the system's electro-pneumatic circuit.

Furthermore, the device constantly measures the temperature of the fluid present in the tank and the level thereof and keeps such parameters constant at all times.

After the predominantly structural description, the operation of the invention in question will now be outlined.

When an operative intends to test a cartridge, all they have to do is insert it into the relative support and secure it. Then the operative has to enter the cartridge type on the control panel and start the device, which will move the cartridge into the tank and then perform a hermetic seal test. Once this phase is complete, the test will begin on the cartridge by introducing air in the sequence envisaged for the three types of pressure input and making the cartridge perform two complete rotations.

All the data is recorded and a test report is issued. If incorrect parameters are found, an anomaly is signalled to the operative via both the recorded parameters and a video so that the latter can identify the non-compliance with the required parameters. If no anomaly is signalled, this means the cartridge has passed the test and therefore meets the specifications required thereof.

At this point, the operative can go on to analyse another cartridge.

Thus the present invention achieves the objects set. The device for testing filter cartridges according to the present invention automatically performs the tests and assesses the characteristics of the filtering material by determining the first bubble point and testing for leaks in the finished cartridge with the integrity test. Indeed, the device in question features fully automatic operation and carries out the test procedure prescribed by standard ISO 2942 which - until now - has always been performed manually by an operative. Furthermore, the device in question can feature semi-automatic operation so as to offer customised testing based on specific test requirements for the cartridge.

Advantageously, the device automatically adapts the operation thereof based on the dimensions of the cartridge undergoing testing and the ambient conditions during testing.

Furthermore, the device can store and replicate a test according to a coded test protocol stored for each cartridge type. In particular, the device in question adapts easily to any type, model, and size of cartridge to be tested.

A further advantage offered by the present device lies in the fact that a test report is automatically generated in electronic and/or paper format for the traceability of the batch and the characteristics thereof.

Advantageously, the device in question speeds up cartridge testing times, contains the costs of these tests (thereby ensuring better management of the production batches) and completely eliminates all those inaccuracies and errors attributable to personnel.

In addition to the explanations so far and as already mentioned, the device can carry out the entire cartridge testing sequence automatically and in compliance with standard ISO 2942, including the determination of the first bubble point in the filtering media and providing - if necessary - a graph of the pressure levels based on the useful time needed to test the behaviour of certain materials that feature coalescence characteristics. In particular, determining the first bubble point accurately and via a coded procedure rather than by eye can be advantageously used for comparisons between different filtering materials and assessments of the filtering capacities of the materials.

A further, not final advantage of the present invention is to have a device for testing filter cartridges which is structurally simple, easy to maintain, as well as compact in size and very functional.

Naturally, further modifications or variants may be applied to the present invention while remaining within the scope of the invention that characterises it.

Claims

1 ) A device for testing filter cartridges with calculation of the first bubble point which is characteristic of each filtering material, the said equipment being characterized by the fact that it consists of: - a containment structure (2) divided into different sectors, the said sectors comprising a test chamber (20), sealed with doors (20a) which insulate the internal environment so that the said environment is not subj ect to interference of any kind originating from the exterior - since tests are performed on a cartridge (5) inside the said chamber -, furthermore comprising a first technical chamber

(21 ), located underneath the test chamber, which houses a tank (3) designed to contain a test fluid (4) and a second technical chamber located behind the other two chambers (20 and 21 ) and designed to house the components used to operate the said equipment,

- a cartridge support unit comprising a horizontal guide (8) which accommodates a sliding, adj ustable support (80) envisaged to support an anchoring element (9) for the cartridge (5),

- an air inlet element 10 located on the opposite side with respect to the anchoring element (9) and connected to a compressor located in the second technical chamber the said element ( 10) being a silicone cone which adapts so as to enter any cartridge because it is both soft and increases in diameter,

- a chain ( 12), protected by a casing and driven by an electric motor ( 120), whose function is to rotate the cartridge on itself by means of a small shaft ( 120a) which enters the cartridge (5), - a support to which the chain ( 12) is anchored so as to move vertically along two guides located in the rear wall of the test chamber (20), the said support being driven by a motor located in the second technical chamber,

- a pressure measurement unit consisting of two measuring systems ( 1 3 and 14),

- management and control means ( 1 8) envisaged to manage and drive the various units and components of the equipment,

the said equipment may operate in a semi-automatic manner, wherein an operator runs part of the operations, and in a totally automatic manner except for the positioning of the cartridge on the anchoring element (9), which is manual.

2) A device for testing filter cartridges according to Claim 1 , characterised by the fact that the said device comprises:

a filtering device (40) composed of a hydraulic filter (40a) managed by a pump (40b) so as to guarantee cleaning and prevent alterations and clogging of the cartridge (5) under test conditions with a consequent incorrect feedback of the value of the pressure at which the first bubble appears, which is a specific characteristic of the filtering material used, the said device (40) featuring a valve (40c) envisaged to drain the test fluid (4) when particular maintenance needs to be carried out or the tank (3 ) must be emptied,

- a temperature control system (6) for the test fluid so as to keepthe viscosity value constant to ensure comparable test results, the said temperature control system comprising a coil (60) immersed in the tank (3) and controlled by at least one probe (61 ) and designed to heat the fluid (4)

- a level control system (7) for the test fluid (4) in the tank (3), which includes a sensor (7a) which reads the height of the fluid level in the tank and signals - in the event - the need for topping up and/or signals the automatic topping up thereof, a float (70) whose function is to signal when the tank is overfull and consequently to stop, sending such signal to a pump (71 ) whose task is to top up the fluid contained in a tank (72).

3) anchorage element (9) features three pins (90) which move inside respective guides (90a) to manage the adjustment and movement of the corresponding brackets (91 ) which open and close to house and secure a cartridge (5) regardless of the diameter thereof and the said support (80), which moves along the guide (8), positions and secures a cartridge with any length while the anchorage element (9) secures cartridges with different diameters, so that the said device can house and test different sized cartridges without any difficulties.

4) A device for testing filter cartridges according to Claim 1 , characterised by the fact that the first pressure measuring system

( 13) is based on the principle of the U-shaped water column, which is located on the rear wall of the test chamber (20), outside the tank while the second measuring system ( 14) is located behind the test chamber within the second technical chamber and comprises pressure transmitters which detect the parameters of the air, converting them into numerical values and an digitally controlled electrical actuator provides an output pressure within the ranges required in order to perform tests and the digital system is integrated into the management and control means ( 1 8), which manage it via dedicated software.

5) A device for testing filter cartridges according to Claim 1 , characterised by the fact that the said tank (3 ) is envisaged to contain a test fluid (4) whose temperature must be within a predetermined range of values (22±5) °C and, in the maj ority of cases, the said fluid is paraffin-based oil, which is filtered continuously so as to remain in suitable, optimal conditions, so as to have correct results and render the results of the tests on the cartridges comparable.

6) A device for testing filter cartridges according to Claim 2, characterised by the fact that the said second probe (62) is envisaged to start operating solely if the first (61 ) has problems and does not work because, if the temperature conditions are not met, the test will not start.

7) A device for testing filter cartridges according to Claim 1 , characterised by the fact that the said device comprises sensors envisaged to guarantee the correct immersion of the cartridge and to detect possible vibrations of the said cartridge so that the tests are carried out with absolutely no vibrations.

8) A device for testing filter cartridges according to Claim 1 , characterised by the fact that the said management and control means ( 1 8) manage the movement of the cartridge electronically both when the said cartridge is immersed and following the test. when it is extracted from the tank (3), and there is a hydraulic limit switch present, which prevents any vertical displacement of the cartridge during the test.

9) A device for testing filter cartridges according to Claim 2, characterised by the fact that the said device operates under electronically regulated pressure through an adjustment unit comprising a chain of electro-pneumatic components which perform micrometric adjustments of the pressure levels and within the electro-pneumatic regulation chain there are four vacuum valves envisaged which need protection in the form of filtration at a level of 5 pm (microns) absolute and are located behind the test chamber in the second technical chamber, wherein the first valve manages the data shown on pressure gauges visible on a control panel, the second manages the inflow of air inside the cartridge, while the third manages and suppliesthe air to the U column and, finally, the fourth manages the release of the air at the end of the test.

10) A device for testing filter cartridges according to Claim 1 , characterised by the fact that the entire pneumatic circuit is hermetically sealed since even the slightest leakage of air would jeopardise reliability and the value of the whole test, given the very low test pressure levels used.

1 1 ) A device for testing filter cartridges according to Claim 1 , characterised by the fact that the system shows on a panel and records all the data relating to variations in pressure throughout the various steps of the test as the time changes, showing - in graphic form - the real pressure trend so as to be able to graphically compare the behaviour of different filter materials under the same conditions of use.

12) A device for testing filter cartridges according to Claim 1 , characterised by the fact that the said management and control means ( 1 8) of the said device provides a report in electronic format with a graphical interface which states the test batch and date for each cartridge type in order to provide proper traceability in real time.

13) A device for testing filter cartridges according to Claim 2, characterised by the fact that the said device constantly measures the temperature of the fluid present in the tank and the level thereof and keeps such parameters constant at all times.

14) A device for checking filter cartridges according to Claims 1 and 2, characterised by the fact that the said device is designed to operate according to the following operating steps:

- the positioning of a cartridge on the cartridge support unit (8) and engagement to the air inlet element ( 1 0) and to the anchoring element (9).

entry of a filter type identification code via the control panel, by an operator, for acknowledgement of the dimensional and structural characteristics of the filter,

closure of the doors of the structure containment (2) so as to insulate the test chamber with respect to the surrounding environment,

- lowering of the cartridge into the tank (3) until the complete immersion thereof. - priming of the cartridge filter material with the fluid (4) present in the tank,

- first intake of air through the cone ( 1 0) in the filter with pressure increased from 0 to 9 mbar slowly and gradually, and performance of two complete rotations of the cartridge driven by the belt (1 2), second intake of air through the cone ( 10) in the filter in three steps, with pressure levels of 3 mbar, followed by 6 mbar, and finishing with 9 mbar, and performance of two complete rotations of the cartridge driven by the belt ( 12),

- third intake of air through the cone ( 10) in the filter with pressure increased rapidly from 0 to 9 mbar, and performance of two complete rotations of the cartridge,

- raising of the cartridge and removal from the fluid and intake of air at a preset pressure level (approximately 1 bar) to expel the fluid which had entered the material previously,

- provision of a report and a graph showing the pressure levels,

- signalling, in the event of anomalies, to an operator, who may then intervene,

- release of the cartridge and insertion of another to be tested.

15) A device for testing filter cartridges according to Claim 14, characterised by the fact that the said device is designed to perform, in an autonomous manner, a hermetic seal test, thus guaranteeing the absence of any incorrect reports of non-compliance of the cartridge before beginning any testing on a cartridge in which:

- a first hermetic seal testing step consists of the equalisation (by means of micrometric air release) of the pressure levels inside and outside the cartridge through the interaction of two of the electro pneumatic valves present in the circuit, followed by

- a stabilisation step which depends on the type of cartridge/filter and the dimensions and characteristics, and the time required for stabilisation is catalogued and filed on the specifications sheet of the cartridge examined, which is entered in the database of the management and control system ( 1 8), in which one of the valves is closed and all the other electro-pneumatic valves are open, the said valves being managed and controlled electronically by specific software, the air inj ection proper begins and continues until the set pressure value is reached through the use of electro-pneumatic regulator in series with a pressure regulator calibrated to one tenth of a bar and all of the aforesaid is retrofitted with a digital pressure transmitter controlled by an electronic system and able to constantly adjust, in a j ogged manner and algebraically the pressure value, until the value set on the panel is reached and maintained, wherein the automatic closing of the main valve, with consequent generation of a hermetic condition allows analysis of the cartridge as per settings.

16) A device for testing filter cartridges according to Claim 13 , characterised by the fact that during operation, in the event of non- compliance of some parameters with respect to those set, the said device signals, both visually and acoustically, an anomaly and interrupts the test procedure.

17) A device for testing filter cartridges according to Claim 13 , characterised by the fact that each step of the test done is filmed by a camera and recorded because, when the device signals an anomaly, the operator upon playing the film can see exactly where the bubble originates and can see what do es not meet the requirements, be it the filter material, the glue on the bottom or on the cartridge material j oint, or anything else and if, during a test step, there is a bubble (recorded as leakage of air from the solenoid valves), the device detects the pressure drop and warns of the presence of an anomaly .