One-way adapter for pressure-measuring devices

Abstract

The invention relates to a one-way adapter by means of which pressure-measuring devices (2) can be fastened to pressure connections (31, 31') of process systems (3) while maintaining sterile conditions. For this purpose, the one-way adapter (1) comprises as components: a separating membrane (11) which is elastic in the provided pressure-measuring region and has a collar (111) running around the edge; and a connector (12), which encloses the separating membrane (11) on the collar (111), by means of which the pressure-measuring device (2) can be fastened to the adapter (1), and with a connection means (121) via which the adapter (12) can be connected to the pressure connection (31) in such a way that the separating membrane (11) separates the process system (3) from the pressure-measuring device (2) in a media-tight manner.

Description

[0001] Disposable adapters for pressure gauges

[0002] The invention relates to a disposable adapter for sterile pressure measurement.

[0003] In process automation technology, field devices are used to acquire relevant process parameters. Suitable measurement principles are implemented in the various types of field devices to acquire these parameters, such as fill level, flow rate, pressure, temperature, pH value, redox potential, or conductivity. The Endress+Hauser Group manufactures and distributes a wide variety of field device types and variants.

[0004] In the case of pressure gauges, the measuring principle frequently used is that the pressure is measured by the deformation of a measuring diaphragm when pressure is applied to one side. The measuring diaphragm can be an integrated part of a semiconductor structure. Such a sensor is described, for example, in publication WO 03 / 106952 A2. However, ceramics (e.g., Al₂O₃) or corrosion-resistant metals can also be used as measuring diaphragm materials. The pressure chamber, which, by design, must be located on the back side between the diaphragm and a non-deformable base body, is designed depending on whether the pressure sensor is used to determine relative, differential, or absolute pressure. In the case of relative or differential pressure measurement, the pressure chamber is completely sealed and pressurized with a vacuum or a constant reference pressure.In differential pressure measurement, the pressure chamber is open to the pressure system against whose pressure the differential pressure is to be determined (i.e., for example, to the ambient atmosphere).

[0005] The mechanical deformation of the measuring membrane is converted into an electrical measurement signal using the (piezo-)resistive or capacitive principle. This means that one or more resistive or capacitive elements are arranged on the measuring membrane, whose resistance or capacitance changes with the deformation. Particularly in pharmaceutical and bioprocess engineering, there are processes where the pressure must be determined under sterile conditions. For the corresponding pressure measuring device, this means that its measuring membrane, as the component in contact with the medium, must be sterilized before each process. However, it is also common to connect the measuring membrane or the pressure measuring device to the corresponding container via a disposable adapter. For this purpose, the adapter includes a separating membrane that provides a media-tight seal between the pressure measuring device and the process container. The separating membrane is designed to transmit the pressure in the process container to the pressure measuring device or the pressure measuring device.to transmit the measurement from its measuring membrane. A corresponding adapter is described, for example, in utility model DE 202015 103 406 U1. Within pharmaceutical and bioprocess engineering, there are processes that, at least in certain sections, take place under pressure and in small volumes. The invention therefore aims to enable measurement even under these conditions.

[0006] The invention solves this problem by means of a disposable adapter by which a pressure gauge based on a measuring membrane can be attached to a pressure port of a process system. For this purpose, the adapter comprises at least the following components:

[0007] - An elastic separating membrane within the intended pressure measuring range, with a collar running around the edge, and

[0008] - a connector that encloses the separating membrane at the collar, or with a connection means via which the adapter can be connected to the pressure port.

[0009] The connector is also used to attach the pressure gauge to the adapter in such a way that the separating membrane isolates the pressure gauge from the process system in a media-tight, i.e. sterile, state when mounted.

[0010] Within the scope of the invention, it is advantageous to design the measuring membrane such that the collar is formed on the surface of the separating membrane facing the pressure gauge. This allows the connector to be designed more compactly, as it reduces the dead volume within the connector. A minimal dead volume, in turn, makes it easier to maintain sterility in the process system.

[0011] If the separating membrane has a pronounced bulge towards the pressure gauge, particularly in the form of a thickening, the separating membrane can, with appropriate connector design, come into contact with the measuring membrane even at a defined negative pressure in the process system, i.e., a minimum pressure lower than standard atmospheric pressure. The resulting force on the measuring membrane at this negative pressure enables the pressure gauge to measure the corresponding pressure value in the process system even at this minimum pressure. To ensure the necessary elasticity within the intended pressure measuring range, i.e., potentially even at the defined negative pressure, it is advisable to manufacture the separating membrane from an elastomeric plastic, particularly a TPE or silicone.

[0012] To enclose the separating membrane and attach it to the pressure port, the connector must be made of appropriately robust materials, although this is not strictly specified within the scope of the invention. From a sterilization and manufacturing perspective, it is particularly advantageous to manufacture the connector from a thermoplastic, such as PP, PC, PPS, PSU, or PEEK. In this case, the connector and the separating membrane can be manufactured in a single process step using two-component injection molding.

[0013] In this context, it is not strictly necessary to design the connector as a single piece. Even if the connector is designed as a two-piece unit, the measuring diaphragm and the first connector part, which encloses the measuring diaphragm at the collar, can be manufactured using two-component injection molding. Alternatively, the connector can also be designed as a two-piece unit in such a way that the separating diaphragm is not enclosed by either connector part, but rather that, after assembly with the connector parts, the separating diaphragm is clamped between the two connector parts at the collar. When designing the connector, it is also important to consider the type of pressure connection to which the adapter will be attached.If the pressure connection is a pipe segment of a pipeline, the entire connector can be designed in a T-shape in a one-piece design, so that the connection element is formed as a pipe segment for a hose- or pipe-shaped pressure connection. Correspondingly, in a two-piece design, the corresponding T-shaped section of the two connector parts between which the separating membrane is clamped can also be designed in this way. Regardless of whether the connector is designed in two parts, the connector, or the connector part that forms the connection element, can be designed in a T-shape so that the connection element of the adapter is formed as a pipe segment for the pipe-shaped pressure connection.

[0014] Especially with a T-shaped design of the connection means, a two-part design of the connector is particularly advantageous, as this increases the modularity of the adapter: In this case, the corresponding T-shaped connector part can be manufactured in versions with different diameters, with the other connector part being compatible with all these versions if designed accordingly.

[0015] Based on the disposable adapter according to the invention, the pressure in a corresponding process system can be determined in accordance with hygienic requirements. For this purpose, the process system must, for example, include a pipe- or flange-shaped pressure connection so that a diaphragm-based pressure gauge can be attached there by means of the disposable adapter. The connector of the adapter, by its design, ensures that the diaphragm of the pressure gauge, via which the pressure is determined, is in contact with the diaphragm when installed, starting at the defined minimum pressure in the process system. A bayonet fitting, a toggle clamp, or a tri-clamp fitting, for example, can be used as a fastening means by which the disposable adapter can be attached to the pressure gauge. The invention is explained in more detail with reference to the following figures. These show:

[0016] Fig. 1: A process system in which the pressure is to be determined,

[0017] Fig. 2: A cross-sectional view of a first embodiment of a disposable adapter according to the invention,

[0018] Fig. 3: a side view of the first version variant,

[0019] Fig. 4: a first cross-sectional view of a second embodiment of the disposable adapter according to the invention, and

[0020] Fig. 5: a second cross-sectional view of the second design variant.

[0021] For a basic understanding of the invention, Fig. 1 shows a container of a process system 3 in which, for example, a reaction of a pharmaceutical or biological process takes place, which requires sterile conditions. Process system 3 here refers not only to individual containers or individual pipelines, but also to combinations thereof, in which a uniform process pressure prevails.

[0022] Depending on the process underway, it is necessary to measure the current process pressure in the vessel or process system 3. In the embodiment shown in Fig. 1, two possible pressure connections 31, 31' are provided on the vessel for this purpose, to which a pressure gauge 2 can be attached either directly or via an adapter 1: On the top of the vessel 3, a vessel opening 31 with a flange connection is installed as a pressure connection, to which a pressure gauge 2 can be attached, if necessary, via a suitable adapter 1. In the illustrated embodiment, a bypass pipeline with a missing pipe segment 31' also runs along the side of the vessel 3. The missing pipe segment 31' again serves as a possible pressure connection for pressure measurement, since a corresponding T-shaped pipe segment can be used here as an adapter 1 for a pressure gauge 2.Membrane-based pressure gauge types 1 are, at least when no adapter 1 is used, attached to the corresponding pressure port 31, 31' in such a way that only its membrane 21 is in contact with the interior of the process system 3. In this case, the membrane 21 simultaneously forms the pressure- and fluid-tight seal of the process system 3 to the outside. For sterile processes, this means that the membrane 21 must be subjected to a corresponding sterilization procedure after each process.

[0023] Alternatively, the pressure gauge 1 can be connected to the pressure port 31, 31' via a disposable adapter 1, whereby the disposable adapter 1 seals the measuring diaphragm 21 against the process system 3 in a fluid-tight manner using a separating diaphragm 11, and vice versa. To ensure that the pressure prevailing in the process system 3 is transmitted to the measuring diaphragm 21, the measuring diaphragm 11 is elastic within the pressure measurement range in which the pressure gauge 2 is intended to detect the pressure in the process system 3. For this purpose, the separating diaphragm 11 can be made of an elastomeric plastic, such as TPE or silicone, with a suitable thickness. By using the disposable adapter 1, sterilization of the pressure gauge 2 can be omitted, as the disposable adapter 1 is replaced after each process.

[0024] A first embodiment of a disposable adapter 1 according to the invention is shown in the cross-sectional view of Fig. 2. The disposable adapter 1 is based on a separating membrane 11 with a collar 111 circumferentially extending around its edge. In the assembled state, the collar 111 is formed on the surface of the separating membrane 11 facing the pressure gauge 2.

[0025] As can be seen from the enlarged view in Fig. 2, the separating membrane 11 has a thickening 112 according to the invention. This ensures that the separating membrane 11 no longer rests against the measuring membrane 21 only below a defined negative pressure in the process system 3. That is, above this defined negative pressure, the separating membrane 11 rests against the measuring membrane 21 due to the thickening 112, causing the latter to bulge. This allows the pressure measuring range of the pressure gauge 2 to begin at this defined negative pressure. In contrast to the thickening 112 shown, this function of the separating membrane 11 can also be achieved, within the scope of the invention, by any other form of pre-bulging that forms on the surface of the separating membrane even without applied pressure.

[0026] In addition to the separating membrane 11, the adapter 1 is based on a connector 12. This has essentially three functions:

[0027] First, the connector 12 serves as a frame for the separating membrane 11 on the collar 111, so that the separating membrane 11 provides a media-tight seal between the pressure gauge 2 and the process system 3. To provide the necessary stability, the connector 12 can be made, for example, from a mechanically stable thermoplastic, such as PP, PC, PPS, PSU, or PEEK. As can be seen from the cross-sectional view in Fig. 2, the connector 12 in this embodiment is designed in two parts, with the collar 111 of the separating membrane 11 clamped between an outer connector part 12a and an inner connector part 12b. Optionally, the two connector parts 12a and 12b can be welded together after clamping the separating membrane 11. The terms "outer" and "inner" refer to the center point of the respective circular membranes 11 and 12b.Instead of a two-part design of the connector 12 with subsequent welding of the two connector parts 12a, b, it is also conceivable to design the connector 12 as a single piece and to manufacture it together with the separating membrane 11 as a single component by two-component injection molding.

[0028] Secondly, the connector 12 serves to attach the pressure gauge 2 to the adapter 1. In the embodiment shown in Fig. 2, a bayonet fitting 22 is provided as the fastening means, which comprises a radially projecting pin on the connector 12 and a corresponding cap on the side of the pressure gauge 2. The term "radial" again refers to the center point of the respective circular diaphragms 11, 21. Thirdly, the connector 12 to the process system 3 functions as a connection means 121, via which the adapter 12 and the pressure gauge 2 connected to it are connected to the pressure port 31, 31'. As can be seen from Fig. 3, the connector 12, or rather the second, inner connector part 12b, is T-shaped in this embodiment. This means that the connection element 121 is designed in this case as a line segment for a hose or pipe-shaped pressure connection 3T.The connector 12 is designed such that the separating membrane 11 runs approximately parallel to the pipe segment. Because the collar 111 of the separating membrane 11 is structurally aligned with the pressure gauge 2, the pipe segment can be designed with a very small dead volume or a small pipe diameter.

[0029] In the embodiment of the disposable adapter 1 according to the invention shown in Figures 4 and 5, the connector 12 is also T-shaped. Here, the connector 12 is again designed in two parts, so that the separating membrane 11 is clamped between the two connector parts 12a, b. Analogous to the embodiment shown in Figure 3, the corresponding line segment is formed by the inner connector part 12b. The enlarged view in Figure 4 also shows that the collar 111 of the separating membrane 11 includes an outer circumferential bead 113. This serves to seal the corresponding gap between the connector parts 12a, 12b when the separating membrane 11 is clamped in place. Furthermore, guide elements 114 are formed at one end area of ​​the collar 111, which engage in corresponding recesses in the inner connector part 12b when clamped and thus simplify the centering of the separating membrane 11.

[0030] In the embodiment shown in Fig. 4 and Fig. 5, the first connector part 12a and the pressure gauge 2 are connected by means of a tri-clamp closure 22' as a fastening means. In contrast to Fig. 1, the collar 111 of the separating membrane 11 is also formed on the surface facing away from the pressure gauge 2. While this does increase the internal dead volume in principle, the connection element 121 to the process system 2, designed as a pipe segment, has a larger pipe diameter in the embodiment shown in Fig. 5 compared to Fig. 2, so that this embodiment of the disposable adapter 1 according to the invention can be used in larger pipe sections. An increased diameter, in turn, makes it possible to integrate flow elements into the pipe segment of the connector 12 to ensure, for example, laminar flow.

[0031] Reference symbol list

[0032] adapter

[0033] Pressure gauge, process system, separation membrane

[0034] connector

[0035] Measuring diaphragm fastening device, 31 ' Pressure connection 1 collar thickening bead 1 connection device

Claims

Patent claims 1. Disposable adapter by means of which a pressure measuring device (2) can be attached to a pressure port (31 , 31 ') of a process system (3), comprising: - An elastic separating membrane (11) within the intended pressure measuring range, with a collar (111) circumferential at its edge, and - a connector (12), o which encloses the separating membrane (11) on the collar (111), o by means of which the pressure gauge (2) can be attached to the adapter (1), and o with a connection means (121), via which the adapter (12) can be connected to the pressure port (31) in such a way that the separating membrane (11) separates the process system (3) from the pressure gauge (2) in a media-tight manner.

2. Adapter according to claim 1, wherein the separating membrane (11) is made of an elastomeric plastic, in particular a TPE or a silicone, and / or wherein the connector (12) is made of a thermoplastic, in particular a PP, PC, PPS, PSU and / or PEEK.

3. Adapter according to claim 1 or 2, wherein the collar (111 ) is formed on a surface of the separating membrane (11 ) directed towards the pressure measuring device (2).

4. Adapter according to one of the preceding claims, wherein the separating membrane (11) has a pronounced protrusion towards the pressure measuring device (2), in particular in the form of a thickening (112).

5. Adapter according to claims 1 to 4, wherein the connector (12) is designed as a single piece.

6. Adapter according to claim 5, wherein the connector (12) and the separating membrane (11) are manufactured by two-component injection molding.

7. Adapter according to claims 1 to 4, wherein the connector (12) is designed in two parts, and wherein the measuring membrane (11) and a first connector part (12a) which encloses the measuring membrane (11) at the collar (111) are manufactured by two-component injection molding.

8. Adapter according to claims 1 to 4, wherein connector (12) is designed in two parts such that the separating membrane (11) is clamped between the two connector parts (12a, 12b) on the collar (111).

9. Adapter according to any of the preceding claims, wherein - in the case of a one-piece design, the connector (12), or - in the case of a two-part design, either one of the two connector parts (12a, 12b) between which the separating membrane (11) is clamped, or the second connector part (12b) which does not enclose the separating membrane (11) is designed in such a T-shape that the connection means (121) forms a line segment for a pipe or hose-shaped pressure connection (3T).

10. Process system in which a pressure is to be determined, comprising: - A pressure connection, especially one shaped like a pipe (31, 3T), - A pressure gauge (2), with a measuring diaphragm (21) via which the pressure can be determined, and a fastening means (22, 22', 22") by means of which the adapter (1) can be attached to the pressure gauge (2). - An adapter (1 ) according to one of the preceding claims, by means of which the pressure measuring device (2) is attached to the pressure connection (31 , 3T), wherein the connector (12) is designed such that the separating membrane (11 ) is in contact with the measuring membrane (21 ) from a defined minimum pressure in the process system (3).

11. Process system according to claims 4 and 10, wherein the connector (12) and the separating membrane (11) are designed such that the separating membrane (11) is in contact with the measuring membrane (21) from a minimum pressure in the process system (3) which is lower than standard atmospheric pressure.

12. Process system according to claim 10 or 11, wherein the fastening means for fastening the adapter (1) to the pressure gauge (2) is configured as - Bayonet fitting (22), - Tension lock, or - Tri-Clamp closure (22') is designed.

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