FITTING AND METHOD OF USING THE FITTING

A fitting for accommodating a sensor includes: an outer housing extending along a first axis including a primary inlet and a primary outlet for medium to flow through the outer housing, a cleaning inflow, and a cleaning outflow; an inner housing extending along the first axis and moveable about the first axis between a measurement position and a service position, the inner housing including a sensor chamber with a secondary inlet and a secondary outlet, wherein the secondary inlet is fluidically connected to the primary inlet, and the secondary outlet is fluidly connected to the primary outlet when the inner housing is in the measurement position, and wherein the cleaning inflow is fluidically connected to the secondary inlet and the cleaning outflow is fluidically connected to the secondary outlet when the inner housing is in the service position; and a sealing unit between the outer housing and the inner housing.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is related to and claims the priority benefit of German Patent Application No. 10 2023 104 708.6, filed Feb. 27, 2023, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a fitting and a method of using the fitting.

BACKGROUND

Fittings, for example, retractable fittings, are widely used in analytical measurement technology and process automation. They are used for removing sensors from the process, and thus from the medium, without interrupting the process and for then reintroducing them into the process. The sensors are fastened in a dip tube and are moved axially by hand or automatically, for example, pneumatically, by means of a drive between a process position (measurement) and a service position (maintenance, calibration, flushing, probe exchange, etc.). These processes take place within a certain period of time, depending on the drift of the measured value or the contamination of the measuring element. The sensors are used to measure one or more physical or chemical process variables.

A great variety of retractable assemblies are offered and marketed by the Endress+Hauser corporate group, for example, under the name “Cleanfit CPA871.” Information about them can be found on the applicant's website, for example, regarding the filing date under: https://www.endress.com/cpa871

Process fittings for sensors (for example, pH sensors) must have special functionalities to enable a sensor to be removed from a running process of a system, for example, for calibration work, etc., without interrupting the process. For this purpose, a fitting generally has a housing in which the sensor is accommodated by a sensor carrier (carriage). The sensor carrier can be moved in these fittings via a drive, manually, pneumatically or electrically, from a measurement position in the process into a second position for service work (calibration on site, rinsing/cleaning) or for removal. A sealing system between the housing and the sensor carrier provides separation from the process chamber. The type of movement of the sensor carrier is dependent on the sealing system.

Sealing rings (O-rings, etc.) are often used, which causes a purely linear movement of the sensor carrier. In the case of linear movements, however, there is the risk that when the fitting is used in a process medium which has a higher viscosity, the sealing rings will become damaged by adhesions of the process medium in the fitting.

A purely rotational movement (rotation/pivoting) would be conceivable, for example, with a plug or ball valve principle. In the case of the plug valve, the sealing effect is brought about by pressing the conical plug against a conical sealing bushing, which results in the required torque being very high. At the same time, the pressure must be continuous.

SUMMARY

It is therefore an object of the present disclosure to provide a fitting which enables easy, reliable and low-maintenance use.

This object is achieved by a fitting according to the present disclosure.

The fitting according to the present disclosure for accommodating a sensor comprises:an outer housing which extends along a first axis and has a primary medium inlet and a primary medium outlet for measuring medium to flow through the outer housing, wherein the outer housing moreover has a cleaning inflow channel, a cleaning outflow channel and a fluid channel;an inner housing which extends along the first axis and can be moved about the first axis between a measurement position and a service position, wherein the inner housing has a sensor chamber with a secondary medium inlet and a secondary medium outlet, wherein the secondary medium inlet is fluidically connected to the primary medium inlet, and the secondary medium outlet is fluidically connected to the primary medium outlet when the inner housing is in the measurement position, wherein the cleaning inflow channel is fluidically connected to the secondary medium inlet, and the cleaning outflow channel is fluidically connected to the secondary medium outlet when the inner housing is in the service position; anda sealing unit which is disposed between the outer housing and the inner housing, wherein the sealing unit is elastic and has a cavity which is fluidically connected to the fluid channel and is suitable for being pressurized by a fluid with a first fluid pressure in order to press the sealing unit against the outer housing and against the inner housing with a first pressing force so that no measuring medium penetrates into the fitting.

The fitting according to the present disclosure enables a sensor to be used in the fitting easily with little effort. Due to the specific seal, the fitting is more secure than conventional fittings and is therefore also lower maintenance than conventional fittings. In particular, when the position of the fitting is changed (e.g., from the measurement position to the service position or vice versa), great force is not required. Likewise, the manufacturing effort of the fitting is less than with conventional fittings with a plug or ball valve principle since greater tolerances are possible and a cone is not necessary. Furthermore, only minimal surfaces are in contact the media in the fitting according to the present disclosure, which minimizes adhering media residues and therefore a blockage risk. In addition, the sealing pressure in the fitting can be adapted to the process pressure in the measuring medium. The sealing effect or the sealing pressure for moving the valve body can also be reduced, which leads to the minimization of wear of the sealing surface and to the reduction of the necessary drive torque.

According to at least one embodiment of the present disclosure, the sealing unit extends around the first axis, and/or around the primary medium inlet as well as around the primary medium outlet.

According to at least one embodiment of the present disclosure, the sealing unit is integrally formed with the outer housing, for example, by a two-component injection molding method.

According to at least one embodiment of the present disclosure, the outer housing has a first half-part and a second half-part, and the fitting also comprises a clamping ring, wherein the clamping ring is suitable for clamping the sealing unit between the clamping ring and the first half-part and between the clamping ring and the second half-part.

According to at least one embodiment of the present disclosure, the cleaning inflow channel opens with an inflow mouth into the secondary medium inlet when the inner housing is in the service position, and the cleaning outflow channel opens with an outflow mouth into the secondary medium outlet when the inner housing is in the service position, wherein the inflow mouth and the outflow mouth are arranged at a distance from one another along the first axis.

According to at least one embodiment of the present disclosure, the fitting also comprises a securing element which is fastened to the outer housing, wherein the inner housing has a groove running around the first axis and the securing element engages in the groove so that a displacement of the inner housing along the first axis is prevented.

According to at least one embodiment of the present disclosure, the fluid channel has a fluid inlet and a fluid outlet, wherein the fluid outlet opens into the cavity of the sealing unit, wherein the fluid channel has a check valve as to prevent a fluid flow from the fluid outlet to the fluid inlet.

The above-mentioned object is also achieved by a further fitting for accommodating a sensor according to present disclosure. The further fitting according to the present disclosure comprises:an outer housing which extends along a first axis and has a primary medium inlet and a primary medium outlet for measuring medium to flow through the outer housing, wherein the outer housing moreover has a cleaning inflow channel, a cleaning outflow channel and a fluid channel;an inner housing which extends along the first axis and can be moved about the first axis between a measurement position and a service position, wherein the inner housing has a sensor chamber with a secondary medium inlet and a secondary medium outlet, wherein the secondary medium inlet is fluidically connected to the primary medium inlet, and the secondary medium outlet is fluidically connected to the primary medium outlet when the inner housing is in the measurement position, wherein the cleaning inflow channel is fluidically connected to the secondary medium inlet, and the cleaning outflow channel is fluidically connected to the secondary medium outlet when the inner housing is in the service position, wherein a gap having a predetermined gap width is formed between the inner housing and the outer housing; anda sealing unit which is arranged in the gap and has a predetermined sealing thickness, wherein the sealing thickness is greater than the gap width so that the sealing unit is pressed against the outer housing and against the inner housing with a first pressing force, wherein the sealing unit is elastic and has a cavity which is fluidically connected to the fluid channel and is suitable for being pressurized by a fluid with a second fluid pressure so that the sealing unit is pressed against the outer housing and against the inner housing with a second pressing force, wherein the second pressing force is less than the first contact pressure.

The above-mentioned object is also achieved by a method of using a fitting according to the present disclosure. The method according to the present disclosure comprises at least the following steps:providing a fitting according to the present disclosure, wherein the inner housing is in the measurement position and the sealing unit is pressurized with a first fluid pressure by a fluid so that the sealing unit is pressed against the outer housing and against the inner housing with a first pressing force so that no measuring medium penetrates into the fitting;pressurizing the sealing unit with a third fluid pressure by a fluid so that the sealing unit is pressed against the outer housing and against the inner housing with a third pressing force;moving the inner housing from the measurement position into the service position; andpressurizing the sealing unit with the first fluid pressure by the fluid so that the sealing unit is pressed against the outer housing and against the inner housing with the first pressing force, and no measuring medium penetrates into the fitting.

The above-mentioned object is also achieved by a further method of using a fitting according to the present disclosure. The further method according to the present disclosure comprises at least the following steps:providing a fitting according to the present disclosure, wherein the inner housing is in the measurement position and the sealing unit is pressed against the outer housing and against the inner housing with a first pressing force so that no measuring medium penetrates into the fitting;pressurizing the sealing unit with a third fluid pressure by a fluid so that the sealing unit is pressed against the outer housing and against the inner housing with a third pressing force;moving the inner housing from the measurement position into the service position; andreleasing the pressurization of the sealing unit with the third fluid pressure so that the sealing unit is pressed with the first pressing force against the outer housing and against the inner housing so that no measuring medium penetrates into the fitting.

FIG.1shows an exemplary embodiment of the fitting1according to the present disclosure with a sensor2accommodated in the fitting1. The sensor2is, for example, a pH sensor.

The fitting1has an outer housing10, an inner housing30as well as a sealing unit40, and is suitable for receiving a sensor2.

DETAILED DESCRIPTION

The outer housing10extends along a first axis A1and has a primary medium inlet11as well as a primary medium outlet12. The primary medium inlet11and the primary medium outlet12enable measuring medium M to flow through the outer housing10. The outer housing10furthermore has a cleaning inflow channel13, a cleaning outflow channel15as well as a fluid channel17(FIGS.1and2). The cleaning inflow channel13has an inflow mouth14, and the cleaning outflow channel15has an outflow mouth16(FIG.2). The outer housing10is preferably configured to be fastened to a container (not shown). The container is, for example, a process container with an opening designed for receiving the fitting1. The outer housing10has a section which is suitable to come into contact with the measurement medium.

The inner housing30extends along the first axis A1and is mounted in the outer housing10. The inner housing30is movable about the first axis A1between a measurement position MP and a service position SP. The inner housing30is, for example, either manually moved via a lever (not shown), or by an electrical or fluidic drive (not shown) between the measurement position MP and the service position SP. The movement of the inner housing30between the positions SP, MP is performed, for example, by hand, mechanically or pneumatically. In the measurement position MP, a measuring medium M is able to flow through the fitting1and in particular the sensor chamber31in which the sensor2is arranged. In the service position SP, the sensor chamber31is suitable for a cleaning fluid and/or a calibration fluid to flow through in order to clean the fitting1and the sensor2or, for example, to calibrate the sensor2. The inner housing30preferably extends partially out of the process container when the fitting1is arranged in the opening of the process container. The inner housing30preferably has a threaded interface as to fasten the sensor2in the inner housing30. Of course, other form-fitting connections, such as bayonet connections are also possible to fasten the sensor2in the inner housing30. According to an embodiment (not shown), the inner housing30optionally also has a sensor carrier or sensor carriage arranged in the inner housing30, in which the sensor is mounted. The sensor carriage allows additional safety functions to be implemented, for example, protection against glass breakage.

The inner housing30has a sensor chamber31with a secondary medium inlet32as well as a secondary medium outlet33. The secondary medium inlet32is fluidically connected to the primary medium inlet11of the outer housing10, and the secondary medium outlet33is fluidically connected to the primary medium outlet12of the outer housing10when the inner housing30is in the measurement position MP (FIG.1).

The cleaning inflow channel13of the outer housing10has a cleaning inlet22and an inflow mouth14. The cleaning inlet22makes it possible to feed a cleaning or calibration fluid into the cleaning inflow channel13(seeFIG.2andFIG.4). Preferably, the cleaning inlet22has, for example, threaded interface, for example, to fasten a hose to the outer housing10. The cleaning inflow channel13opens with the inflow mouth14into the secondary medium inlet32when the inner housing30is in the service position SP (FIG.2). The cleaning inflow channel13is therefore fluidically connected to the sensor chamber31.

The cleaning outflow channel15of the outer housing10has a cleaning outlet23and a outflow mouth16. The cleaning outlet23makes it possible to evacuate a cleaning or calibration fluid from the cleaning outflow channel15(seeFIGS.2and4). Preferably, the cleaning outlet23has a thread, for example, in order for example, to fasten a hose to the outer housing10. The cleaning outflow channel15opens with the outflow mouth16into the secondary medium outlet33when the inner housing30is in the service position SP (FIG.2). The cleaning outflow channel15is therefore fluidically connected to the sensor chamber31.

The inflow mouth14and the outflow mouth16of the outer housing10are preferably arranged at a distance from one another along the first axis A1. This enables the advantage that the cleaning fluid, for example, air, is better conducted out of the sensor chamber31.

According to an embodiment, the sealing unit40is disposed between the outer housing10and the inner housing30. The sealing unit40is elastic and has a cavity41which is fluidically connected to the fluid channel17(FIG.1). The fluid outlet19of the fluid channel17opens into the cavity41. The cavity41is suitable for being pressurized with a fluid via the fluid channel17with a first fluid pressure P1in order to press the sealing unit40against the outer housing10and against the inner housing30with a first pressing force F1. This ensures that no measuring medium M penetrates into the fitting1. The fluid channel17preferably has a non-return valve configured to prevent a fluid flow from the fluid outlet19to the fluid inlet18. The first fluid pressure P1is preferably selected such that it is greater than a pressure of the measuring medium M. The first fluid pressure P1is preferably selected depending on the pressure of the measuring medium M.

When the sealing unit40is pressurized with the fluid with the first fluid pressure P1, the sealing unit40is in a sealing state.

When the sealing unit40is pressurized with the fluid with a second fluid pressure P2which is preferably greater than or equal to the pressure of the measuring medium M, the sealing unit40is in a relaxed state.

The sealing unit40preferably runs around the first axis A1(seeFIG.3) and/or around the primary medium inlet11and around the primary medium outlet12(seeFIGS.1and3).

According to the embodiment of the fitting1shown inFIGS.1-4, the outer housing10has a first half-part20and a second half-part21.

The fitting1comprises a clamping ring50. The clamping ring50is suitable for clamping the sealing unit40between the clamping ring50and the first half-part20and between the clamping ring50and the second half-part21(seeFIGS.1and2).

According to a further embodiment (not shown), the sealing unit40is integrally formed with the outer housing10, for example, by a two-component injection molding method.

According to at least one embodiment of the fitting1which is compatible with all possible mentioned embodiments, the fitting1furthermore comprises a securing element60which is fastened to the outer housing10. The inner housing30furthermore includes a groove34running around the first axis A1. The securing element60is arranged in the outer housing10in such a way that the securing element60engages in the groove so that a displacement of the inner housing30along the first axis A1is prevented. The securing element60is, for example, a clamping screw, a split pin, or a similar component.

A gap3having a predetermined (e.g., preset, selected) gap width4is formed (e.g., created, defined) between the inner housing30and the outer housing10. The sealing unit40is disposed in the gap3and has a predetermined (e.g., preset, selected) sealing thickness42(seeFIG.3).

According to an alternative embodiment of the sealing unit40, the sealing unit40has a predetermined sealing thickness42. The sealing thickness42is greater than the gap width4so that the sealing unit40is pressed against the outer housing10and against the inner housing30with a first pressing force F1. Thanks to the first pressing force F1, the sealing unit40is in the pressed state.

According to such an embodiment, the sealing unit40is suitable for entering the relaxed state by pressurizing the cavity41with a fluid which has a second fluid pressure P2which is less than or equal to the pressure of the measuring medium M so that the sealing unit40is pressed against the outer housing10and against the inner housing30with a second contact pressure F2, wherein the second contact pressure is less than the first contact pressure.

Methods of using the fitting1are discussed below. According to an embodiment of the method, the first above-described embodiment of the sealing unit40may be used.

According to a first step, the method comprises providing the above-described fitting1. The inner housing30is in the measuring position MP, and the sealing unit40is pressurized with a first fluid pressure P1by the fluid so that the sealing unit40is pressed against the outer housing10and against the inner housing3with the first pressing force F1, and no measuring medium M penetrates into the fitting1.

This is followed by a step of pressurizing the sealing unit40with a third fluid pressure P3by a fluid so that the sealing unit40is pressed against the outer housing10and against the inner housing30with a third pressing force F3. The third pressing force F3is lower than the first pressing force F1. The sealing unit40is therefore in the relaxed state.

This is followed by a step of moving the inner housing30from the measurement position MP (FIG.1) into the service position SP (FIG.2).

Next comes a step of pressurizing the sealing unit40with the first fluid pressure P1by the fluid so that the sealing unit40is pressed against the outer housing10and against the inner housing30with the first pressing force F1. The first fluid pressure P1is preferably greater than or equal to the pressure of the measuring medium M so that no measuring medium M penetrates into the fitting1.

According to a further embodiment of the method, the second above-described embodiment of the sealing unit40may be used. As explained above, in such an embodiment, the sealing unit40has a sealing thickness42which is greater than the gap width4of the gap3between the inner housing30and the outer housing10. Since the sealing unit40is elastic, the sealing unit40is therefore pressed against the outer housing10and against the inner housing30even with a first pressing force F1without pressurizing the cavity41with a fluid. Here too, the first pressing force F1is selected such that a medium pressure is resisted, and no measuring medium M penetrates into the fitting1.

In another step, the sealing unit40is pressurized with a third fluid pressure P3by a fluid so that the sealing unit40is pressed against the outer housing10and against the inner housing30with a third pressing force F3. The third fluid pressure P3is preferably equal to the pressure of the measuring medium M. In any case, the third pressing force F3is lower than the first pressing force F1. This makes it possible for the inner housing30to be rotatable relative to the outer housing10with a small amount of force. In this step, pressurizing the sealing unit40with a fluid preferably means pressurizing it with a vacuum. The sealing unit40is therefore in the relaxed state.

This is followed by a step of moving the inner housing30from the measurement position MP into the service position SP takes place.

Then comes a step of releasing the pressurization of the sealing unit40with the third fluid pressure P3so that the sealing unit40is pressed with the first pressing force F1against the outer housing10and against the inner housing30, and no measuring medium M penetrates into the fitting1. The sealing unit40is therefore in the pressed state.