METHOD FOR VERIFYING A DENSITY AND / OR VISCOSITY MEASURING DEVICE IN A MEASURING POINT

Description

[0001] The invention relates to a method for verifying a density and / or viscosity measuring device in a measuring point of a process plant during ongoing operation and a device for checking a density and / or viscosity measuring device in a measuring point of a process plant during ongoing operation of the process plant by means of a MEMS-based master or control density measuring device.

[0002] Density and / or viscosity measuring devices are used, in particular, to continuously measure the density and / or viscosity of a medium in a process plant during operation, i.e., while a process is running. The measurement of density and / or viscosity is carried out under the process conditions necessary for the process to be carried out. These are, in particular, temperature and pressure.

[0003] To ensure the reliability of the measurement results, these measuring instruments must be checked periodically. There are various ways to perform this check. Common methods include: Sampling in an open container and measurement with a hydrometer (measuring spindle) or, alternatively, with a portable handheld density meter based on a U-tube transducer in the field. This method has the disadvantage that the measurement cannot be performed at process pressure. This is particularly problematic with media containing volatile components (vapor pressures significantly below 1 bar abs.), as the sample can change during sampling and measurement. Sampling in a closed container and subsequent measurement in the laboratory with a pycnometer or a laboratory instrument based on the U-tube transducer method are alternatives. These laboratory measurements offer greater accuracy than field measurements. However, even here, measurements cannot be taken under process conditions (temperature and pressure). Furthermore, volatile components can evaporate even in a closed container and escape upon opening. This also potentially contaminates the sample.

[0004] Field measurements at process pressure using a pressure pycnometer. Pycnometers provide a precise, reproducible volume measurement of a medium in a glass or metal flask. By weighing the empty and filled flask, the density of the medium can be determined. Using robust and insulated metal flasks equipped with pressure and temperature gauges, measurements can also be taken under high pressures and at process temperatures. With careful work and adherence to thorough cleaning and testing procedures, this method is very accurate and allows measurements at process pressures and temperatures. However, the complex cleaning of the flasks is problematic. Particularly with viscous media with high viscosity, some of the medium can remain on the flask walls and thus affect the result.

[0005] A disadvantage of all the described methods is that the medium must be disposed of after the measurement.

[0006] To address this disadvantage, efforts have recently been made to establish an alternative verification method in industry. This involves using a master or control density meter, which is installed in series with the measuring device being checked / verified within the system. The installation is designed by providing a branch line to which the master or control density meter can be connected. To minimize any alteration of the medium's flow characteristics through the system, the branch line is adapted to the main process line where the measuring device is located; for example, the branch line has the same nominal pipe diameter as the process line and / or is connected in series with it. Such measures are not only very time-consuming to implement but also relatively expensive.A prior art document relevant to the invention is patent document EP 0 874 976 A1.

[0007] It is therefore the object of the present invention to overcome the disadvantages of the prior art described above.

[0008] The problem is solved according to the invention by the method according to claim 1 and the device according to claim 9.

[0009] The inventive method for verifying a density and / or viscosity measuring device, preferably one subject to calibration requirements, in a measuring point of a process plant during ongoing operation in which a medium, in particular a medium containing hydrocarbons, flows through a main channel of the process plant, comprises the following steps: Providing a secondary channel that acts as a bypass to the main channel, wherein the secondary channel is fluidically connected to the main channel via two sections of the main channel with different diameters; providing a MEMS-based master or control density meter in the secondary channel such that the medium flows through the MEMS-based master or control density meter; performing at least one verification measurement with the MEMS-based master or control density meter; verifying the density and / or viscosity meter based on the at least one verification measurement performed by the MEMS-based master or control density meter.

[0010] The method according to the invention has many advantages over the methods described above, for example: Verification measurements are performed continuously under real process conditions and can be carried out and repeated as needed. No special equipment is required, such as sample containers for hydrometer measurements or sample bottles for subsequent laboratory measurements, or special connections with shut-off valves, pressure and temperature sensors, plus a scale with reference weights for field measurements with a pressure pycnometer. The measurement is simple and less prone to error. The measurement process can be automated if required. This measurement method is particularly advantageous in applications where the density of the medium changes rapidly. No medium is lost, and therefore no waste is generated.

[0011] According to the invention, the method further comprises the following step: Providing a main channel adapter located in or on the main channel, which is configured to control the flow of the medium through the secondary channel such that the secondary channel is only traversed by the medium when the MEMS-based master or control density meter is mechanically connected to the main channel adapter.

[0012] Another advantageous embodiment of the method according to the invention further comprises the following step: Providing at least one replaceable filter element in the secondary channel, preferably as part of the sensor adapter, wherein the filter element is arranged in the direction of flow upstream of the MEMS-based master or control density meter, so that the medium is filtered before entering the MEMS-based master or control density meter.

[0013] In particular, the embodiments may provide that the MEMS-based master or control density meter is detachably connected to the main channel adapter only for the at least one verification measurement and is thus exposed to the medium flow, and / or that the MEMS-based master or control density meter is detached from the main channel adapter after the at least one verification measurement during operation. The main channel adapter is preferably provided during the construction of the process plant and positioned accordingly in the main channel so that it remains permanently in the plant. Because the main channel adapter remains permanently in the plant, the master or control density meter can subsequently be connected to the main channel adapter for performing the verification measurement without tools.

[0014] Another advantageous embodiment of the method according to the invention provides that the MEMS-based master or control density meter is checked, preferably repeatedly, and particularly preferably in a laboratory, with a reference medium which has preferably been measured using a measurement procedure traceable to national standards. In particular, the embodiment may provide that the MEMS-based master or control density meter is used at another measuring point for the verification of another density and / or viscosity meter, and that the other measuring point preferably has a further main channel adapter to which the MEMS-based master or control density meter is mechanically connected.

[0015] Another advantageous embodiment of the method according to the invention provides that the MEMS-based master or control density measuring device is sealed and attached to the main channel adapter.

[0016] Another advantageous embodiment of the method according to the invention provides that, for the verification of the density and / or viscosity measuring device, a temperature and / or pressure representative of the measuring point during operation is used.

[0017] The invention further relates to a device for verifying a density and / or viscosity measuring device, preferably one subject to calibration requirements, in a measuring point of a process plant during ongoing operation by means of a MEMS-based master or control density measuring device, wherein the measuring point comprises at least the following: a main channel through which a medium, in particular a hydrocarbon, flows during the ongoing operation of the process plant, wherein the main channel has at least two sections with different diameters; the density and / or viscosity measuring device arranged in or on the main channel for determining a primary density and / or viscosity parameter of the medium; a secondary channel which is fluidically connected to the main channel in the two sections in such a way that the secondary channel is connected as a bypass to the main channel; a [missing information] in or on the main channel.a main channel adapter arranged on the main channel, configured to control the flow of the medium through the secondary channel such that the medium flows through the secondary channel only when the MEMS-based master or control density meter is mechanically connected to the main channel adapter; the MEMS-based master or control density meter arranged in the secondary channel for determining a density and / or viscosity value of the medium during operation, the density and / or viscosity value serving to verify the primary density and / or viscosity value determined by the density and / or viscosity meter.

[0018] An advantageous embodiment of the device according to the invention further comprises a sensor adapter comprising the MEMS-based master or control density measuring device, wherein the sensor adapter and the main channel adapter are adapted to each other in such a way that the sensor adapter can be mechanically detachably connected to the main channel adapter and furthermore, that the medium only flows through the secondary channel formed in the main channel adapter and sensor adapter in a connected state.

[0019] In particular, the design may provide that the sensor adapter further comprises at least one replaceable filter element, which is arranged upstream of the MEMS-based master or control density meter in the direction of flow, so that the medium is filtered before entering the MEMS-based master or control density meter, and / or that the sensor adapter has a filter holder, preferably accessible laterally, which is designed to hold the filter element in an installation position in the sensor adapter, so that the medium flows through the filter element, and is further designed to eject the filter element, preferably laterally, as required, so that the filter element can be replaced.

[0020] A further advantageous embodiment of the device according to the invention further comprises an additional measuring point with an additional main channel adapter for mechanically and fluidically connecting the MEMS-based master or control density measuring device.

[0021] A further advantageous embodiment of the device according to the invention further comprises a flow computer which is configured to verify the primary density and / or viscosity value of the medium determined by the density and / or viscosity measuring device on the basis of the density and / or viscosity value of the medium determined by the MEMS-based master or control density measuring device during the ongoing operation of the process plant.

[0022] In particular, the design may further include a temperature and / or pressure measuring device for determining a temperature and / or pressure representative of the medium flowing through the measuring point, wherein the temperature and / or pressure is supplied to the flow computer and the flow computer is further configured to use the temperature and / or pressure representative of the measuring point for verifying the primary density and / or viscosity parameter.

[0023] A further advantageous embodiment of the device according to the invention provides that the main channel adapter and the sensor adapter have a quick-coupling system which enables a fluidic connection of a part of the secondary channel formed in the main channel adapter to a part of the secondary channel formed in the sensor adapter. In particular, the device can be designed such that the quick-coupling system is configured such that the two parts of the secondary channel can be separated from each other again after the fluidic connection. The quick-coupling system can further be configured such that the two parts of the secondary channel can be fluidically connected to each other under pressure during operation when the sensor adapter is mechanically attached to the main channel adapter. No tools are required for mounting and dismounting the sensor adapter in the field.

[0024] The invention is explained in more detail with reference to the following drawings. They show: Fig. 1 : a schematic representation of a first general embodiment of the invention, Fig. 2 a) and b) : a schematic representation of a second embodiment of the invention shown in greater detail, and Fig. 3 : a schematically represented process flow of the method according to the invention.

[0025] Figure 1Figure 1 shows an exemplary section of a process plant 3 in which a process is carried out. A section of the process plant 3 includes a density and / or viscosity measuring device 1, for example, a Promass Q from Endress+Hauser. Of course, this could also be a different Coriolis flow meter and / or density and / or viscosity measuring device. The density and / or viscosity measuring device 1 serves to measure the density ρ1 and / or viscosity η1 of the medium at a measuring point 2 of the process plant 3 in a calibration setting. Furthermore, the density and / or viscosity measuring device 1 can be used to measure a first temperature T1, which is preferably used to determine the density ρ1 and / or viscosity η1. A temperature and pressure measuring device 16 is connected to the density and / or viscosity measuring device 1. This device is designed to measure a temperature T and a pressure p representative of the medium flowing through the measuring point.This measuring unit, consisting of a density and / or viscosity measuring device 2 and a temperature and pressure measuring device 16, is connected via a main channel adapter 9 to a MEMS-based master or control density measuring device 10, which is configured to determine a verification density ρ2 and / or verification viscosity η2. Furthermore, the master or control density measuring device can detect a second temperature T2, which is preferably used to determine the density ρ2 and / or viscosity η2. In contrast to the other two measuring devices, the MEMS-based master or control density measuring device 10 is only temporarily installed at the measuring point to verify the density and / or viscosity measuring device 10 operating in calibration mode.The process plant 3 can further comprise a flow converter 17, hereinafter also referred to as the flow computer, which is configured to calculate a volumetric flow rate of the medium through the measuring point under standard conditions in the calibration facility. For this purpose, the flow computer 17 is supplied with the density ρ1, viscosity n1, and, if applicable, the first temperature T1 determined by the density and / or viscosity measuring device 1, as well as the temperature T and pressure p determined by the temperature and pressure measuring device 16. Furthermore, for verification of the calibrated density and / or viscosity measuring device 1, the verification density ρ2 and / or verification viscosity n2 determined by the MEMS-based master or control density measuring device 10, as well as, if applicable, the second temperature T2, are supplied to the flow computer 17. The measuring devices can be connected, for example, via a digital or analog interface 18 on the devices and the flow computer.The Flowcomputer 17 is further equipped to perform a verification of the density and / or viscosity determined by the density and / or viscosity measuring device on the basis of the verification density ρ 2 and / or verification viscosity η 2 determined by the temporarily connected MEMS-based master or control density measuring device, the determined temperatures T 1 , T and T 2 and the pressure p.

[0026] Since all measurements are essentially simultaneous, it can be assumed that the medium was the same. Therefore, for each set of measurement points, a measurement error can be determined according to Formula 1 under the prevailing measurement conditions (T, p, ρ, η, ...): e _ ρ 1 T , p , ρ , η , … = ρ 1 − ρ 2 − A * T 1 − T 2 − B p 1 − p 2 where e_ρ 1 is a process-condition-dependent measurement error, A is the temperature coefficient and B is the pressure coefficient of the medium of density ρ 1 at the current process conditions T and p.

[0027] Compensation for the pressure difference between the two density sensors is typically unnecessary, since the influence of pressure (for gasoline B = 0.08 kg / m³ < bar - 1 < ) on the fluid density is small and the measurement is performed at practically the same pressure p, resulting in formula 2: e _ ρ 1 T , p , ρ , η , … = ρ 1 − ρ 2 − A * T 1 − T 2

[0028] Temperature compensation makes sense for temperature deviations greater than 0.1 K (for gasoline, A = -0.9 kg / m³ < K - 1 < ). For temperature differences smaller than 0.1 K, the formula simplifies further to: e _ ρ 1 T , p , ρ , η , … = ρ 1 − ρ 2

[0029] All determined process-condition-dependent measurement errors can be stored in the flow computer and used to compensate for future density or viscosity measurements. To determine the measurement error for a measurement under process conditions where no verification point exists, interpolation is performed between the adjacent verification points.

[0030] Fig. 2 a) and b)Figure 1 shows a second embodiment of the invention, in which several measuring points 2, 15 are shown by way of example. The measuring points 2, 15 are each introduced into a main channel 4 through which a medium 5 flows during the ongoing operation of the process plant. The measuring points are usually not fluidically connected to each other, but are installed in several different fluid paths in different parts of the plant, which are usually operated with different media.

[0031] The media typically contain a hydrocarbon. Examples include crude oil, gasoline, kerosene, petrol, diesel, heating oil, heavy oil, mineral oil, lubricating oil, biodiesel, ethanol, methanol, cooking oil, etc. The main channels 4 are configured in the area of ​​the measuring points by a change in cross-section 20 such that at least two sections 6, 7 with different diameters D1, D2 are present. In the main channel 4, at least one measuring unit 19 is arranged for each measuring point 2, 15. This unit consists of a density and / or viscosity measuring device 1 for determining a primary density and / or viscosity parameter of the medium 5 and a temperature and pressure measuring device 16.

[0032] Measuring points 2 and 15 each also include a main channel adapter 9, which is mechanically attached to the main channel, e.g. by means of a screw connection (in Fig. 2 a) and b)(not shown separately), is attached. A portion of the respective secondary channel 8a is formed in the main channel adapter 9, for example by means of corresponding bores. The main channel adapter 9 is arranged on the main channel in such a way that the two portions of the secondary channel 8a formed in the main channel adapter are fluidically connected to the main channel at the two areas with different diameters.

[0033] A main channel adapter 9 attached to the main channel 4 can be used, as shown in the Fig. 2At the measuring point shown on the right, a sensor adapter 13 is attached. The sensor adapter 13 includes the MEMS-based master or control density meter 10, which is temporarily attached for verification purposes. For this purpose, the sensor adapter 13 and the main channel adapter 9 are adapted to each other such that the sensor adapter 13 can be mechanically detachably connected to the main channel adapter 9. A quick-coupling system can also be provided for a fluidic connection of the part of the secondary channel 8a formed in the main channel adapter to the part of the secondary channel 8a continued in the sensor adapter 13, which allows for a fluidic connection of the two secondary channel parts during operation. The quick-coupling system is designed such that the two parts of the secondary channel 8a, 8b can be fluidically separated again when the sensor adapter is mechanically detached from the main channel adapter.Furthermore, the main channel adapter 9 comprises two valves 11 which are switched to an open position when a master or control density meter 10 is connected, so that the medium 5 can flow through the part of the secondary channel 8a formed in the main channel adapter 9 and the part of the secondary channel 8a continued in the sensor adapter 13, and which are switched to a closed position when a master or control density meter 10 is not connected, so that no medium can escape.

[0034] This means that the valves are designed and arranged in the main channel adapter such that the medium only flows through the secondary channel when a MEMS-based master or control density meter 10 is mechanically connected to the main channel adapter 9. Furthermore, this also means that the secondary channel 8a, 8b represents a bypass to the main channel 4. The specific design of the cross-sectional change determines the flow direction of the medium through the secondary channel 8a, 8b. According to the in Fig. 2 a) In the illustrated and preferred example, the cross-sectional change of the main channel is designed such that the medium 3 initially flows through a region with a smaller diameter D1 before flowing through a region with a larger diameter D2. This results in the medium 3 flowing against the flow direction in the main channel 4 through the secondary channel 8a, 8b when the valves 11 are open. Fig. 2 a) and b)This is represented by two arrows indicating the flow direction in the secondary channel. Alternatively, the change in cross-section 20 can also be exactly the opposite, so that the medium 3 first flows through a region with a larger diameter before flowing through a region with a smaller diameter. This is the case, for example, when the flow in the main channel is in the opposite direction to that in Fig. 2 a) The specified flow direction is used. In this case, the medium 3 would flow through the secondary channel in the same direction as in the main channel, so that the secondary channel is always traversed in the same direction, regardless of the flow direction in the main channel.

[0035] To protect the MEMS-based master or control density meter 10 from potential particles in the medium 3, at least one filter element 12 can be provided in the sensor adapter 13. To allow for the replacement of the filter element 12, a filter holder 14 can be provided, which holds the filter element 12 in a predetermined installation position within the sensor adapter 13. The predetermined installation position is defined in the sensor adapter such that, viewed in the direction of flow, the filter element is located in the secondary channel upstream of the MEMS-based master or control density meter 10. Furthermore, the filter element 12 can be removed from the predetermined position via the filter holder 14 for replacement and, for example, guided laterally out of the sensor adapter 13.

[0036] Fig. 2 a)Figure 2 shows a measuring point 2 in which the MEMS-based master or control density measuring device 10 was briefly inserted into the measuring point with two series-arranged (redundant) measuring units 19 via the main channel adapter to perform a verification measurement. Furthermore, the figures show Fig.2 b) To illustrate one aspect of the invention, two further measuring points 15 are shown, which were preferably installed during the construction of the process plant so that they are prepared for the subsequent temporary attachment of the MEMS-based master or control density measuring device. In this way, the further measuring points 15 can be verified using the same master or control density measuring device 10. Fig. 2 a) and b)This is represented by an arrow. An advantage of the invention is therefore that a single MEMS-based master or control density measuring device 10 can be used to verify several arbitrary density and / or viscosity measuring devices in the process plant.

[0037] Fig. 3 Figure 1 shows a schematic representation of the process flow of the inventive method for verifying a density and / or viscosity measuring device. The density and / or viscosity measuring device is located at a measuring point of a process plant and serves to determine the density and / or viscosity of a medium that flows through the main channel during operation of the process plant.

[0038] The method, in a first step S100, provides for the initial provision of a secondary channel, which is fluidically configured as a bypass to a main channel. This secondary channel is provided, in particular, by a previously described main channel adapter, which is attached to a section of the main line exhibiting a change in cross-section, for example, by means of two flanges. The main channel adapter is preferably configured to control the flow of the medium through the secondary channel such that the medium only flows through the secondary channel when the MEMS-based master or control density meter is connected to the main channel adapter. This can be achieved, for example, by two valves, preferably check valves, arranged in the portion of the secondary channel formed within the main channel adapter.

[0039] To protect the MEMS-based master or control density meter from possible contamination by, for example, particles in the medium, an optional intermediate step S102 allows an interchangeable filter element to be arranged in the secondary channel upstream of the MEMS-based master or control density meter.

[0040] The method further provides in a second process step S200 that a MEMS-based master or control density meter is made available for a verification measurement by mechanically attaching a sensor adapter to the main channel adapter. Preferably, the MEMS-based master or control density meter is only temporarily or for a short period of time provided at the measuring point for the purpose of carrying out the verification measurement. After the verification measurement, the MEMS-based master or control density meter can be removed from the measuring point and, for example, used at another measuring point for a different verification measurement.

[0041] In a third process step S300, the inventive method provides that at least one verification measurement is performed at the measuring point during operation using the MEMS-based master or control density meter. The verification measurement determines a verification density and / or a verification viscosity using the MEMS-based master or control density meter. The verification density and / or the verification viscosity is transmitted to a flow computer, which also receives the density and / or viscosity data from the density and / or viscosity meter being verified. The transmission of the verification density and / or the verification viscosity can be performed electronically via an interface to the flow computer, or manually, e.g., by hand or using a separate computer program that is not compatible with the flow computer.

[0042] In the next process step S400, the density and / or viscosity measuring device is verified using the verification measurement previously performed by the MEMS-based master or control density measuring device. Preferably, the verification is performed by the flow computer.

[0043] In a final, possibly also first optional step, the master or control density meter is checked in the laboratory with a reference medium (S500) which was measured using a measurement procedure traceable to national standards. Reference symbol list

[0044] 1 Density and / or viscosity measuring device 2 Measuring point 3 Process plant 4 Main channel 5 Medium 6 First section of the main channel 7 Second section of the main channel 8a, 8b Side channel 9 Main channel adapter 10 MEMS-based master or control density measuring device 11 Valves 12 Filter element 13 Sensor adapter 14 Filter holder 15 Additional measuring point 16 Temperature and pressure measuring device 17 Flow converter or flow computer 18 Interface 19 Measuring unit 20 Cross-sectional change 21 Quick-coupling system D1 First diameter D2 Second diameter T Temperature relevant for the measuring point (current process condition) p Pressure relevant for the measuring point (current process condition) T1 First temperature T2 Verification temperature or second temperature ρ1 Density η1 Viscosity ρ2 Verification density η2 Verification viscosity S100 - S500 process steps

Claims

1. Method for verifying a density and / or viscosity measuring device subject to calibration requirements at a measuring point of a process plant during ongoing operation, wherein a medium, in particular a hydrocarbon-containing medium, flows through a main channel of the process plant, comprising the following steps: • Providing a bypass channel that is connected to the main channel and fluidically linked to two regions of the main channel having different diameters (S100); • Providing a MEMS-based master or control density measuring device in the bypass channel such that the MEMS-based master or control density measuring device is flowed through by the medium (S200); • Providing a main channel adapter arranged in or on the main channel, which is configured to control the flow of the medium through the bypass channel in such a way that the bypass channel is only flowed through by the medium when the MEMS-based master or control density measuring device is mechanically connected to the main channel adapter (S101); • Carrying out at least one verification measurement with the MEMS-based master or control density measuring device (S300); • Verifying the density and / or viscosity measuring device based on the at least one verification measurement performed by the MEMS-based master or control density measuring device (S400).

2. Method according to claim 1 or 2, further comprising the following step: • Providing at least one replaceable filter element in the bypass channel, preferably as part of the sensor adapter, the filter element being arranged upstream of the MEMS-based master or control density measuring device in the direction of flow, so that the medium is filtered before entering the MEMS-based master or control density measuring device (S102).

3. Method according to claim 2 or 3, wherein the MEMS-based master or control density measuring device is detachably connected to the main channel adapter only for the at least one verification measurement and is thus flowed through by the medium.

4. Method according to the preceding claim, wherein the MEMS-based master or control density measuring device is detached from the main channel adapter after the at least one verification measurement during ongoing operation.

5. Method according to one of the preceding claims, wherein the MEMS-based master or control density measuring device is checked, preferably repeatedly and particularly preferably in a laboratory, using a reference medium that has preferably been measured using a measurement procedure traceable to national standards (S500).

6. Method according to one of the preceding claims, wherein the MEMS-based master or control density measuring device is used at another measuring point to verify another density and / or viscosity measuring device, and the other measuring point preferably has an additional main channel adapter to which the MEMS-based master or control density measuring device is mechanically connected.

7. Method according to one of claims 1 to 3 or 7, wherein the MEMS-based master or control density measuring device is sealed (tamper-proof) when attached to the main channel adapter.

8. Method according to one of the preceding claims, wherein a temperature and / or pressure representative of the measuring point during ongoing operation is used for verifying the density and / or viscosity measuring device.

9. Device for verifying a density and / or viscosity measuring device (1) subject to calibration requirements at a measuring point (2) of a process plant (3) during ongoing operation using a MEMS-based master or control density measuring device (10), wherein the measuring point (2) comprises at least the following: • a main channel (4) through which, during ongoing operation of the process plant, a medium (5), in particular a hydrocarbon-containing medium, flows, the main channel (4) having at least two regions (6, 7) with different diameters (D1, D2); • the density and / or viscosity measuring device (1) arranged in or on the main channel (4) to determine a primary density and / or viscosity value of the medium (5); • a bypass channel (8a, 8b) that is fluidically connected to the main channel (4) in the two regions (6, 7) such that the bypass channel (8a, 8b) is configured as a bypass to the main channel (4); • a main channel adapter (9) arranged in or on the main channel (4), which is configured to control a flow of the medium through the bypass channel such that the bypass channel is only flowed through by the medium when the MEMS-based master or control density measuring device is mechanically connected to the main channel adapter; • the MEMS-based master or control density measuring device (10) arranged in the bypass channel (8a, 8b) for determining a density and / or viscosity value of the medium (5) during ongoing operation, wherein the density and / or viscosity value serves to verify the primary density and / or viscosity value determined by the density and / or viscosity measuring device (1).

10. Device according to the preceding claim, further comprising a sensor adapter (13) including the MEMS-based master or control density measuring device (10), wherein the sensor adapter (13) and the main channel adapter (9) are matched to each other such that the sensor adapter (13) is detachably connectable to the main channel adapter and such that only in the connected state does the medium (5) flow through the bypass channel (8) formed in the main channel adapter (9) and the sensor adapter (13).

11. Device according to the preceding claim, wherein the sensor adapter (13) further comprises at least one replaceable filter element (12) which is arranged upstream of the MEMS-based master or control density measuring device (10) in the direction of flow such that the medium (5) is filtered before entering the MEMS-based master or control density measuring device (10).

12. Device according to the preceding claim, wherein the sensor adapter comprises a filter holder (14), preferably laterally accessible, which is designed to hold the filter element in an installed position in the sensor adapter (13) such that the filter element (12) is flowed through by the medium (5), and further designed to dispense the filter element (12) laterally if necessary so that the filter element (12) can be replaced.

13. Device according to one of claims 10 to 13, further comprising an additional measuring point (15) with an additional main channel adapter for mechanically and fluidically connecting the MEMS-based master or control density measuring device.

14. Device according to one of claims 10 to 14, further comprising a flow computer configured to verify the primary density and / or viscosity value of the medium determined by the density and / or viscosity measuring device based on the density and / or viscosity value of the medium determined by the MEMS-based master or control density measuring device during ongoing operation of the process plant.

15. Device according to the preceding claim, further comprising a temperature and / or pressure measuring device to determine a temperature and / or pressure representative of the medium flowing through the measuring point, wherein the temperature and / or pressure is supplied to the flow computer, and wherein the flow computer is further configured to use the representative temperature and / or pressure to verify the primary density and / or viscosity value.

16. Device according to one of claims 11 to 16, wherein the main channel adapter and the sensor adapter comprise a quick-coupling system (21) that establishes a fluid connection between a part of the bypass channel (8a) formed in the main channel adapter and a part of the bypass channel (8b) formed in the sensor adapter (13).

17. Device according to the preceding claim, wherein the quick-coupling system is designed such that the two parts of the bypass channel (8a, 8b) can be separated from each other again after being fluidically connected.