Selection of Zero Verification Criteria for Vibration Meter Zero Verification

Abstract

Meter electronics (20) is provided for selecting a zero verification criterion for performing a zero verification of a vibrometer (5). The meter electronics (20) comprises an interface (401) communicatively coupled to a sensor assembly (10) containing a fluid, and a processing system (402) communicatively coupled to the interface (401). The processing system (402) is configured to determine a characteristic of the fluid and select a zero verification criterion value for the sensor assembly (10) based on the characteristic of the fluid.

Description

[Technical Field]

[0001] The embodiments described below relate to verifying the operation of a vibrometer, and more particularly to selecting a zero verification criterion for zero verification of a vibrometer. [Background technology]

[0002] Vibrometers, such as Coriolis mass flow meters, liquid densitometers, gas densitometers, liquid viscometers, gas / liquid specific gravity meters, gas / liquid relative density meters, and gas molecular weight meters, are commonly known and used to measure fluid properties. Generally, a vibrometer comprises a sensor assembly and meter electronics. The material within the sensor assembly may be flowing or stationary. The vibrometer may be used to measure the mass flow rate, density, or other properties of the material within the sensor assembly.

[0003] To measure such fluid properties of a material, the vibrometer may need to use a reference zero flow value. The reference zero flow value may be equivalent to the zero flow value of the measured property. The actual non-zero property may be quantified as a scaled or unscaled difference from the reference zero flow value. As can be appreciated, accurate measurement of the actual non-zero property may depend on an accurate reference zero flow value. An accurate reference zero flow value may be determined using zero calibration. The accuracy of the reference zero flow value may be verified by zero verification. Zero calibration and zero verification may be performed by fluidly isolating the vibrometer so that any measurement can be correctly assumed to reflect a property having a zero flow value (e.g., zero flow).

[0004] FIG. 1 illustrates a system 1 capable of performing zero verification and zero calibration of a vibrometer 5. As shown in FIG. 1, the system 1 is comprised of a meter inlet block valve 2a and a meter outlet block valve 2b. The meter inlet and outlet block valves 2a and 2b are configured to prevent fluid flow. Therefore, fluid flow through the vibrometer 5 can be zero. Also shown is a fluid bypass loop 3 consisting of a bypass inlet pipe 3a, a bypass shutoff valve 3b, and a bypass outlet pipe 3c. The bypass inlet pipe 3a, the bypass shutoff valve 3b, and the bypass outlet pipe 3c are configured to allow fluid to bypass the vibrometer 5 when the bypass shutoff valve 3b is open. Upstream of the vibrometer 5 are a blowdown valve port 4a and a thermowell port 4b.

[0005] During zero verification and zero calibration, the meter inlet and outlet block valves 2a, 2b are closed, thereby preventing fluid flow through the vibrometer 5. This is sometimes referred to as the zero flow state of the vibrometer 5. During zero flow verification and zero calibration, the vibrometer 5 may measure one or more zero flow values, which may be values ​​related to zero flow of fluid. In a Coriolis meter, the zero flow value may be the time delay or phase difference between the sensor signals when the vibrometer 5 is in the zero flow state.

[0006] The vibrometer 5 may use a reference zero flow value to calculate the flow rate of the fluid through the vibrometer 5. During zero calibration, the vibrometer 5 may determine one or more zero flow values ​​that can be used to calculate a reference value. During zero verification, the vibrometer 5 may compare the one or more zero flow values ​​to a reference to determine whether the flow rate of the fluid can be calculated using the reference zero flow value. If the reference zero flow value is not acceptable, a zero calibration may be performed.

[0007] A predetermined reference zero flow value may be compared to one or more zero flow values ​​to determine whether the reference zero flow value can be used to calculate the flow rate of the fluid. Such a comparison may determine whether a zero calibration should be performed using the zero verification criterion. However, the zero verification criterion may not be suitable for a particular process. Furthermore, various processes may be used in a given location, which may require different degrees of accuracy in flow measurement. Therefore, it is necessary to select a zero verification criterion for zero flow verification of the vibrometer. Summary of the Invention

[0008] Meter electronics for selecting a zero verification criterion for performing zero verification of a vibrometer is provided. According to an embodiment, the meter electronics includes an interface communicatively coupled to a sensor assembly containing a fluid, and a processing system communicatively coupled to the interface. The processing system is configured to determine a characteristic of the fluid and select a zero verification criterion value for the sensor assembly based on the characteristic of the fluid.

[0009] A method for selecting a zero verification reference for performing zero verification of a vibrometer includes containing a fluid in a sensor assembly, determining a characteristic of the fluid, and selecting a zero verification reference value for the sensor assembly based on the characteristic of the fluid.

[0010] A vibrometer (5) capable of selecting a zero verification criterion for performing zero verification comprises a sensor assembly (10) containing a fluid and meter electronics (20) communicatively coupled to the sensor assembly (10).

[0011] Aspects According to one aspect, meter electronics for selecting a zero verification criterion for performing zero verification of a vibrometer includes an interface communicatively coupled to a sensor assembly containing a fluid, and a processing system communicatively coupled to the interface, wherein the processing system is configured to determine a characteristic of the fluid and select a zero verification criterion value for the sensor assembly based on the characteristic of the fluid.

[0012] Preferably, the processing system configured to determine a property of the fluid comprises a processing system configured to determine at least one of the density and phase of the fluid.

[0013] Preferably, the processing system configured to determine the phase of the fluid comprises a processing system configured to determine a parameter of the fluid and to determine the phase of the fluid based on the parameter of the fluid.

[0014] Preferably, the processing system configured to determine the phase of the fluid comprises a processing system configured to determine that the phase of the fluid is one of a gas and a liquid, and the fluid is a single-phase fluid.

[0015] Preferably, the processing system configured to select a zero verification criterion for the sensor assembly based on the property of the fluid comprises a processing system configured to select a zero verification criterion from two or more zero verification criterions.

[0016] Preferably, one of the two or more zero verification criteria is associated with the fluid being a gas, and another of the two or more zero verification criteria is associated with the fluid being a liquid.

[0017] According to one aspect, a method for selecting a zero verification criterion for performing zero verification of a vibrometer includes containing a fluid in a sensor assembly, determining a characteristic of the fluid, and selecting a zero verification criterion value for the sensor assembly based on the characteristic of the fluid.

[0018] Preferably, determining the properties of the fluid includes determining at least one of the density and the phase of the fluid.

[0019] Preferably, determining the phase of the fluid includes determining a parameter of the fluid and determining the phase of the fluid based on the parameter of the fluid.

[0020] Preferably, determining the phase of the fluid includes determining that the phase of the fluid is one of a gas and a liquid, and the fluid is a single-phase fluid.

[0021] Preferably, selecting a zero verification criterion for the sensor assembly based on the characteristics of the fluid includes selecting a zero verification criterion from two or more zero verification criterions.

[0022] Preferably, one of the two or more zero verification criteria is associated with the fluid being a gas, and another of the two or more zero verification criteria is associated with the fluid being a liquid.

[0023] According to one aspect, a vibrometer capable of selecting a zero verification criterion for performing zero verification comprises a sensor assembly containing a fluid and meter electronics communicatively coupled to the sensor assembly. [Brief explanation of the drawings]

[0024] Like reference numbers refer to like elements in all drawings. It should be understood that the drawings are not necessarily to scale. [Figure 1] 1 shows a system 1 capable of performing zero verification and zero calibration of a vibrometer 5. [Figure 2] 1 shows a vibrometer 5 that allows the selection of a zero verification criterion for performing a zero verification of the vibrometer 5. [Figure 3] 1 shows a block diagram of a vibrometer 5, including a block diagram representation of the meter electronics 20. [Figure 4]1 shows the meter electronics 20 for selecting a zero verification criterion for performing a zero verification of the vibrometer 5. [Figure 5] 5 shows a graph 500 illustrating the AGA11 standards for tolerances on flow measurements. [Figure 6] 6 shows a zero verification graph 600 illustrating the zero verification of the vibrometer 5. [Figure 7] 7 illustrates a method 700 for selecting a zero verification criterion for performing a zero verification of a vibrometer. DETAILED DESCRIPTION OF THE INVENTION

[0025] 1-7 and the following description illustrate specific examples to teach those skilled in the art how to make and use the best mode of embodiments for selecting a zero verification reference for zero verification of a vibrometer. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of this description. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations for selecting a zero verification reference for zero verification of a vibrometer. As a result, the embodiments described below are not limited to the specific examples described below, but are limited only by the claims and their equivalents.

[0026] FIG. 2 illustrates a vibrometer 5 that can select a zero verification criteria for performing zero verification of the vibrometer 5. As shown in FIG. 2, the vibrometer 5 includes a sensor assembly 10 and meter electronics 20. The sensor assembly 10 responds to the mass flow rate and density of a process material. The meter electronics 20 connects to the sensor assembly 10 via leads 100 and provides density, mass flow rate, and temperature information, as well as other information, via port 26.

[0027] The sensor assembly 10 includes a pair of manifolds 150 and 150', flanges 103 and 103' having flange necks 110 and 110', a pair of parallel conduits 130 and 130', a driver 180, a resistance temperature detector (RTD) 190, and a pair of pickoff sensors 170l and 170r. The conduits 130 and 130' have two essentially straight inlet legs 131 and 131' and outlet legs 134 and 134' that converge toward each other at the conduit mounting blocks 120 and 120'. The conduits 130 and 130' bend at two symmetrical locations along their lengths and are essentially parallel throughout their entire lengths. Brace bars 140 and 140' function to define axes W and W' about which each conduit 130 and 130' oscillates. Legs 131, 131′ and 134, 134′ of conduits 130, 130′ are fixedly attached to conduit mounting blocks 120 and 120′, which are fixedly attached to manifolds 150 and 150′. This provides a continuous closure material path through sensor assembly 10.

[0028] When flanges 103 and 103', having holes 102 and 102', are connected via inlet end 104 and outlet end 104' to a process line (not shown) carrying the process material being metered, the material enters the meter at inlet end 104 through orifice 101 in flange 103 and is directed through manifold 150 to conduit mounting block 120, having surface 121. Within manifold 150, the material is split and directed through conduits 130, 130'. Upon exiting conduits 130, 130', the process material is recombined into a single stream within block 120', having surface 121' and manifold 150', before being directed to outlet end 104', which is connected to the process line (not shown) by flange 103', having hole 102'.

[0029] The conduits 130, 130' are selected to have substantially the same mass distribution, moment of inertia, and Young's modulus about bending axes W-W and W'-W', respectively, and are appropriately mounted in the conduit mounting blocks 120, 120'. These bending axes pass through the brace bars 140, 140'. To the extent that the conduit's Young's modulus changes with temperature, affecting flow rate and density calculations, an RTD 190 is attached to the conduit 130' to continuously measure the temperature of the conduit 130'. The temperature of the conduit 130', and therefore the voltage appearing across the RTD 190 for a given current passing through it, is governed by the temperature of the material passing through the conduit 130'. The temperature-dependent voltage appearing across the RTD 190 is used by the meter electronics 20 in a well-known manner to compensate for changes in the modulus of elasticity of the conduits 130, 130' due to any changes in the conduit temperature. The RTD 190 is connected to the meter electronics 20 by leads 195.

[0030] Both conduits 130, 130' are driven in opposite directions about their respective bending axes W and W' in what is referred to as the first out-of-phase bending mode of the vibrometer by a driver 180. This driver 180 may comprise any one of a number of well-known configurations, such as a magnet attached to conduit 130' and opposing coils attached to conduit 130 through which an alternating current flows to vibrate both conduits 130, 130'. An appropriate drive signal 185 is applied to driver 180 by meter electronics 20 via leads.

[0031] Meter electronics 20 receives the RTD temperature signal on lead 195 and the sensor signal 165 appearing on lead 100, which carries left and right sensor signals 165l and 165r, respectively. Meter electronics 20 generates a drive signal 185 appearing on a lead to driver 180, causing conduits 130 and 130' to vibrate. Meter electronics 20 processes left and right sensor signals 165l and 165r and RTD signal 195 to calculate the mass flow rate and density of material passing through sensor assembly 10. This information, along with other information, is applied by meter electronics 20 as a signal via path 26. A more detailed description of meter electronics 20 follows below.

[0032] Figure 3 shows a block diagram of the vibrometer 5, including a block diagram representation of the meter electronics 20. As shown in Figure 3, the meter electronics 20 is communicatively coupled to the sensor assembly 10. As described above with reference to Figure 2, the sensor assembly 10 includes left and right pickoff sensors 170l, 170r, a driver 180, and a temperature sensor 190, which are communicatively coupled to the meter electronics 20 via a set of leads 100 via a communication channel 112. Meter electronics 20 provides drive signals 185 via leads 100. More specifically, meter electronics 20 provides drive signals 185 to drivers 180 within sensor assembly 10. Additionally, sensor signals 165, including left sensor signal 165l and right sensor signal 165r, are provided by sensor assembly 10. More specifically, in the illustrated embodiment, sensor signals 165 are provided by left and right pickoff sensors 170l, 170r within sensor assembly 10. As can be appreciated, sensor signals 165 are each provided to meter electronics 20 via communication channel 112.

[0033] Meter electronics 20 includes a processor 210 communicatively coupled to one or more signal processors 220 and one or more memories 230. Processor 210 is also communicatively coupled to user interface 30. Processor 210 is communicatively coupled to a host via a communications port via port 26 and receives power via power port 250. Processor 210 may be a microprocessor, although any suitable processor may be used. For example, processor 210 may be comprised of sub-processors, such as a multi-core processor, a serial communications port, a peripheral interface (e.g., a serial peripheral interface), on-chip memory, an I / O port, or the like. In these and other embodiments, processor 210 is configured to perform operations on received and processed signals, such as digitized signals.

[0034] The processor 210 may receive the digitized sensor signals from one or more signal processors 220. The processor 210 may also be configured to provide information such as a phase difference, a property of the fluid in the sensor assembly 10, etc. The processor 210 may provide the information to a host via a communication port. The processor 210 may also be configured to communicate with one or more memories 230 to receive and / or store information in the one or more memories 230. For example, the processor 210 may receive calibration coefficients and / or a sensor assembly zero (e.g., a phase difference when the flow is zero) from the one or more memories 230. Each of the calibration coefficients and / or the sensor assembly zero may be associated with the vibrometer 5 and / or the sensor assembly 10, respectively. The processor 210 may use the calibration coefficients to process the digitized sensor signals received from the one or more signal processors 220.

[0035] The one or more signal processors 220 are shown as consisting of an encoder / decoder (CODEC) 222 and an analog-to-digital converter (ADC) 226. The one or more signal processors 220 may condition analog signals, digitize the conditioned analog signals, and / or provide digitized signals. The CODEC 222 is configured to receive the sensor signals 165 from the left and right pickoff sensors 170l, 170r. The CODEC 222 is also configured to provide the drive signals 185 to the driver 180. In alternative embodiments, more or fewer signal processors may be used.

[0036] As shown, the sensor signal 165 is provided to the CODEC 222 via a signal conditioner 240. The drive signal 185 is provided to the driver 180 via the signal conditioner 240. Although the signal conditioner 240 is shown as a single block, the signal conditioner 240 may be comprised of signal conditioning components such as two or more operational amplifiers, filters such as low-pass filters, and voltage-to-current amplifiers. For example, the sensor signal 165 may be amplified by a first amplifier, and the drive signal 185 may be amplified by a voltage-to-current amplifier. The amplification can ensure that the magnitude of the sensor signal 165 is close to the full-scale range of the CODEC 222.

[0037] In the illustrated embodiment, the one or more memories 230 are comprised of read-only memory (ROM) 232, random access memory (RAM) 234, and ferroelectric random access memory (FRAM®) 236. However, in alternative embodiments, the one or more memories 230 may be comprised of more or less memory. Additionally or alternatively, the one or more memories 230 may be comprised of different types of memory (e.g., volatile, non-volatile, etc.). For example, a different type of non-volatile memory, such as an erasable programmable read-only memory (EPROM), may be used in place of the FRAM 236. The one or more memories 230 may be storage devices configured to store process data, such as drive or sensor signals, mass flow or density measurements, etc.

[0038] Mass flow measurements can be generated according to the following formula:

number

number

[0039] The measured time delay Δt includes a computationally derived (i.e., measured) time delay value, including the time delay between pickoff sensor signals, such as that due to the Coriolis effect associated with mass flow through the vibrometer 5. The measured time delay Δt is a direct measurement of the mass flow rate of the flowing material as it flows through the vibrometer 5. The zero-flow time delay Δt includes the time delay at zero flow rate. The zero-flow time delay Δt is a zero-flow value that may be determined at the factory and programmed into the vibrometer 5. The zero-flow time delay Δt is an exemplary zero-flow value. Other zero-flow values, such as a phase difference, time difference, etc., determined at a zero-flow condition may also be used. The value of the zero-flow time delay Δt may not change even when flow conditions are changing. The mass flow rate value of the material flowing through the vibrometer 5 is determined by multiplying the difference between the measured time delay Δt and the reference zero-flow value Δt by the flow calibration factor FCF. The flow calibration factor FCF is proportional to the physical stiffness of the vibrometer.

[0040] With respect to density, the resonant frequency at which each conduit 130, 130' may vibrate may be a function of the square root of the spring constant of the conduit 130, 130' divided by the total mass of the conduit 130, 130' containing the material. The total mass of the conduit 130, 130' containing the material may be the mass of the conduit 130, 130' plus the mass of the material within the conduit 130, 130'. The mass of the material within the conduit 130, 130' is directly proportional to the density of the material. Therefore, the density of the material may be proportional to the square of the period at which the conduit 130, 130' containing the material vibrates multiplied by the spring constant of the conduit 130, 130'. Therefore, by determining the period at which the conduit 130, 130' vibrates and scaling the result appropriately, an accurate measurement of the density of the material contained within the conduit 130, 130' can be obtained. The meter electronics 20 can determine the period or resonant frequency using the sensor signal 165 and / or the drive signal 185. The conduits 130, 130' can vibrate in multiple vibration modes.

[0041] [Calibration] The vibrometer 5 may be calibrated with a factory zero flow value while the vibrometer 5 is in a no-flow or zero-flow state. A user may additionally and optionally perform a push-button calibration at any time to obtain a push-button zero flow value. Additionally or alternatively, the vibrometer may automatically perform a calibration to obtain an automatic zero flow value. The zero flow value used to measure the fluid flow rate may be a factory zero flow value, a push-button zero flow value, an automatic zero flow value, or any other suitable zero flow value.

[0042] During zero calibration of the vibrometer 5, measurements, stored values / constants, user settings, stored tables, etc. may be used. The calibration may condition and compensate for the flow meter conditions of the vibrometer 5. Conditions may include, but are not limited to, user-entered conditions, measured conditions, inferred conditions, etc. Conditions may include temperature, fluid density, flow rate, meter specifications, viscosity, Reynolds number, post-calibration compensation, etc. Additionally, different constants, such as, but not limited to, a flow calibration factor (FCF), may be applied based on operating conditions or user preferences.

[0043] The initial zero flow value may be determined during calibration, which is performed as part of the initial factory setup of the vibrometer 5. This may involve placing the vibrometer 5 in a no-flow or zero-flow state and determining, for example, a time delay or phase difference between the left and right sensor signals 165l, 165r. The determined value is stored in one or more memories 230 as the initial zero flow value and used as the reference zero flow value. For example, in the case of equation [1] above, the reference zero flow value may be the ΔT0 term, which may be the zero flow or zero-flow time delay between the left sensor signal 165l and the right sensor signal 165r. Once the reference zero flow value is determined, a flow calibration factor (FCF) may be established, which, as can be seen from equation [1] above, is the time delay Δt measured and mass flow rate

number

[0044] [Zero Verification] The zero verification may include comparing the new zero flow value to a reference zero flow value. For example, the new zero flow value may be compared to a factory-determined zero flow value (e.g., a factory zero flow value), although any suitable reference zero flow value may be used. The new zero flow value may be determined, for example, by averaging multiple zero flow value measurements taken while the vibrometer 5 is installed in the process line but fluidly isolated as described above with reference to FIG. 1.

[0045] Comparing the new zero flow value to the reference zero flow value may include comparing multiple zero flow value measurements to the reference zero flow value. If the multiple zero flow value measurements are not within an acceptable range of the reference zero flow value (e.g., a "predetermined boundary," a "zero stability value," etc.), the reference zero flow value is no longer valid, and the new zero flow value may be stored as the reference zero flow value. If the new zero flow value is within an acceptable range of the reference zero flow value, the reference zero flow value may be valid, and the new zero flow value may or may not be stored as the reference zero flow value.

[0046] However, the tolerance of the reference zero flow value may be based on calibration of the vibrometer 5 at factory conditions, which may not be suitable for all processes. Also, after installation, the vibrometer 5 is subject to mounting, operating, and / or process conditions that may differ from factory conditions and be more specialized. For example, mounting conditions may cause a relatively small shift (e.g., within the tolerance of the reference zero flow value) in the actual zero flow time delay of the conduits 130, 130′. Furthermore, the process in which the vibrometer 5 is used may have mass flow measurement tolerances that require a tighter tolerance of the reference zero value.

[0047] Thus, even if a zero flow value measurement is within an acceptable range of the reference zero flow value, the reference zero flow value may be invalid for the process. For example, if the bias indicator for the reference zero flow value indicates that the reference zero flow value causes a measurement bias that causes the flow measurement to fall outside of an acceptable range of flow measurements, the reference zero flow value may be invalid. This determination and evaluation of the bias indicator for the reference zero flow value may be performed in addition to, or instead of, determining whether multiple zero flow value measurements are within an acceptable range of the reference zero flow value.

[0048] The bias indicator for the reference zero flow value may be any indicator that can prove that the reference zero flow value causes measurement bias. For example, the bias indicator may be composed of a central tendency value and a variance value associated with the zero flow value measurements. The central tendency value may be the mean of the zero flow value measurements, and the variance value may be the standard deviation of the new zero flow value measurements. In another example, the bias indicator may be the ratio (e.g., sign ratio) of the positive or negative value of the difference between the new zero flow value measurements and the reference zero flow value to the total number of new zero flow value measurements. However, any suitable bias indicator that can reliably show that the reference zero flow value causes measurement bias may be used.

[0049] Zero verification may include these and other zero verification criteria depending, for example, on the particular process, fluid type, etc. For example, as described above, vibrometer 5 may measure liquids or gases. The zero verification criteria for liquids may differ from the zero verification criteria for gases. The zero verification criteria may have different tolerances, thresholds, etc. for the reference zero flow value, for example. Thus, meter electronics 20 may be configured to select the zero verification criteria.

[0050] FIG. 4 illustrates meter electronics 20 for selecting a zero verification criteria for performing zero verification of vibration meter 5. As shown in FIG. 4, meter electronics 20 includes an interface 401 and a processing system 402. Meter electronics 20 receives a vibration response from a sensor assembly, such as sensor assembly 10. Meter electronics 20 processes the vibration response to obtain flow characteristics of the flowable material flowing through sensor assembly 10. Meter electronics 20 may also perform checks, verifications, calibration routines, etc. to ensure that the flow characteristics of the flowable material are accurately measured.

[0051] The interface 401 may receive the sensor signal 165 from one of the pickoff sensors 170l, 170r shown in FIGS. 2 and 3. The interface 401 may perform any necessary or desired signal conditioning, such as formatting, amplification, buffering, or the like. Alternatively, some or all of the signal conditioning may be performed in the processing system 402. Additionally, the interface 401 may enable communication between the meter electronics 20 and an external device. The interface 401 may be capable of any method of electronic, optical, or wireless communication. The interface 401 may provide information based on the vibration response. The interface 401 may even be coupled to a digitizer, such as the CODEC 222 shown in FIG. 3, where the sensor signal includes an analog sensor signal. The digitizer samples and digitizes the analog sensor signal to generate a digitized sensor signal.

[0052] The processing system 402 performs the operations of the meter electronics 20 and processes the flow measurements from the sensor assembly 10. The processing system 402 executes one or more processing routines, thereby processing the flow measurements to generate one or more flow characteristics. The processing system 402 is communicatively coupled to the interface 401 and configured to receive information from the interface 401.

[0053] Processing system 402 may comprise a general-purpose computer, a microprocessing system, a logic circuit, or any other general-purpose or customized processing device. Additionally or alternatively, processing system 402 may be distributed across multiple processing devices. Processing system 402 may also include any type of integrated or stand-alone electronic storage medium, such as storage system 404.

[0054] The storage system 404 can store vibrometer parameters and data, software routines, constant values, and variable values. In one embodiment, the storage system 404 includes routines executed by the processing system 402, such as an operation routine 410 for the vibrometer 5, a zero calibration routine 420, and a zero verification routine 430. The storage system can also store statistical values, such as the mean, standard deviation, and confidence interval.

[0055] The operating routine 410 may determine a mass flow value 412 and a density value 414 based on the sensor signals received by the interface 401. The mass flow value 412 may be a frequency-independent mass flow value, a directly measured mass flow value, etc. For example, as described above, the mass flow rate may be determined using an equation that does not include frequency or frequency-dependent values ​​such as density. The mass flow value 412 may be determined from sensor signals such as the time delay between the left and right pickoff sensor signals. The density value 414 may also be determined from the sensor signals, for example, by determining the frequency from one or both of the left and right pickoff sensor signals.

[0056] The zero calibration routine 420 may perform the zero verification described above and store the initial or factory zero as a reference zero flow value 422. As described above, the reference zero flow value 422 may be used to calculate the mass flow value 412. The zero calibration routine 420 may also determine and store a zero stability value as a reference zero stability value 424. Additionally or alternatively, the reference zero flow value 422 and the reference zero stability value 424 may be determined by calibration routines stored and executed on an external device, such as a factory calibration platform that performs the initial calibration of the vibrometer 5.

[0057] The zero verification routine 430 may verify that the reference zero flow value 422 is acceptable, for example, by using the reference zero stability value 424. For example, the zero verification routine 430 may measure the zero flow value under a no-flow or zero-flow condition of the vibrometer 5 and store the measured zero flow value as the measured zero flow value 432. The zero verification routine 430 may determine whether the measured zero flow value 432 is within the reference zero stability value 424.

[0058] Additionally or alternatively, the zero verification routine 430 may determine a bias indicator value 434 for the reference zero flow value 422. The bias indicator value 434 may indicate that the reference zero flow value 422 may cause measurement bias in the mass flow value 412. As described above, the bias indicator value 434 for the reference zero flow value 422 may be composed of a central tendency value and a variance value associated with the measured zero flow value 432. For example, the central tendency value may be the average of multiple difference values ​​between the measured zero flow value 432 and the reference zero flow value 422, and the variance value may be the standard deviation of the multiple differences about the average.

[0059] The zero verification routine 430 may also select a zero verification criterion. For example, the zero verification routine 430 may select the zero verification criterion based on the characteristics of the fluid contained in the sensor assembly 10. The zero verification criterion may be comprised of the reference zero stability value 424 and / or other values. For example, as shown in FIG. 4 , the first zero verification criterion 440 may include a first bias indicator reliability threshold 442. Thus, the zero verification routine 430 may determine whether the measured zero flow value 432 is within the reference zero stability value 424 and whether the bias indicator value 434 is within the first bias indicator reliability threshold 442. The first bias indicator reliability threshold 442 may be, for example, a 75% sign ratio, zero, or a dead band around zero if a null hypothesis is used as described above.

[0060] The zero verification routine 430 may also select a second zero verification criterion 450, consisting of, for example, a second zero stability value 452 and a second bias indicator confidence threshold 454. The second zero stability value 452 may not be the same as the reference zero stability value 424. For example, the second zero stability value 452 may be less than the reference zero stability value 424. Thus, if the vibrometer 5 is to be used in a process requiring a zero stability value less than the reference zero stability value 424, the second zero stability value 452 may be used.

[0061] By way of example, for an uncustodial transfer of a liquid, the zero verification routine 430 may determine whether the measured zero flow value 432 is within the reference zero stability value 424. For a custodial transfer of a liquid, the zero verification routine 430 may determine whether the measured zero flow value 432 is within the reference zero stability value 424 and the bias indicator value 434 is within the first bias indicator reliability threshold 442. For a custodial transfer of a gas, the zero verification routine 430 may determine whether the measured zero flow value 432 is within the second zero stability value 452 and the bias indicator value 434 is within the first bias indicator reliability threshold 442. These are merely examples, and any suitable combination of tolerance ranges or tolerance ranges for the reference zero flow value may be used for any suitable characteristic of the fluid.

[0062] The first and / or second bias indicator confidence thresholds 442, 454 may be user-configurable. For example, a user may set a dead band around zero to achieve a desired zero verification standard for a particular application. Thus, a confidence interval value, described in more detail below, stored as a variance value of the bias indicator value 434, may be configured by the manufacturer, and a user may configure the first and / or second bias indicator confidence thresholds 442, 454 to be compared to the variance value, more specifically, the confidence interval in this example. As an example, a manufacturer may set a two-sigma confidence interval value that can be compared to zero (i.e., no dead band) in one application, while in a more rigorous application, a user may set a dead band value that, when compared to the two-sigma confidence interval value, is comparable to a three-sigma confidence interval value compared to zero. A user may set the code ratio value as the bias indicator confidence threshold with reference to the code ratio. The code ratio value may require fewer computing resources than comparing the confidence interval to the dead band to determine whether the bias indicator is sufficiently reliable. The code ratio may also correspond to the confidence interval. For example, a code ratio value of 75% may correspond to approximately 1 sigma or a 68% confidence level. These and other values ​​may be set and stored by a user as first and / or second bias indicator confidence thresholds 442, 454 to which the bias indicator value 434 is compared. The processing system 402 may also determine the first or second zero verification criteria 440, 450. For example, the processing system 402 may calculate the second zero stability value 452 from the reference zero stability value 424. In one particular example, the second zero stability value 452 may be calculated by multiplying the reference zero stability value 424 by, for example, 0.5 to scale the reference zero stability value 424 to the second zero stability value 452. Additionally or alternatively, the first and / or second bias indicator confidence thresholds 442, 454 may be calculated as well.

[0063] The ratio used to scale the first or second zero validation criteria 440, 450 may be based on a characteristic of the fluid. For example, the ratio may be the ratio of error bands associated with a low or high expected flow rate of the fluid, whether the fluid is a gas or a liquid, whether the density of the fluid is greater than or less than a density threshold, etc. In one particular example, the ratio may be determined by dividing the error band associated with a high expected flow rate of the fluid by the error band associated with a low expected flow rate of the fluid. This example is described below with reference to FIG. 5.

[0064] FIG. 5 shows a graph 500 illustrating the AGA11 standards for tolerances related to flow measurement. As shown in FIG. 5, graph 500 includes a measured flow rate axis 510 and a percentage error axis 520. The measured flow rate axis 510 may be in any suitable units, such as kilograms per minute (kg / min). The measured flow rate axis 510 ranges from zero to a maximum flow rate, Qmax. The percentage error axis 520 ranges from −1.60 to 1.60, although any suitable range and / or units may be used.

[0065] Graph 500 also includes an error plot 530 illustrating an exemplary error versus flow rate relationship for a Coriolis meter. Error plot 530 has an associated repeatability bar for each corresponding flow rate that indicates the range that the measurements are expected to fall within. As can be seen, error plot 530 decreases as the flow rate increases, significantly improving measurement stability. As can also be seen, the repeatability bar and error increase as the measured flow rate decreases. The increase in the repeatability bar and error may be due to an increased contribution of nonlinear effects to the flow rate measurements. Other error plots may be used, including those with smaller increases or those in which the error is primarily linear, for example, due to a reference zero flow rate value.

[0066] Graph 500 further includes an error limit band 540 having a low flow error limit band 540a and a normal flow error limit band 540b. Low flow error limit band 540a and normal flow error limit band 540b are symmetrical about the zero error rate axis. Low flow error limit band 540a corresponds to the range of flow rates between a minimum flow rate Qmin and a threshold flow rate Qt. Normal flow error limit band 540b is for flow rates between a threshold flow rate Qt and a maximum flow rate Qmax. As can be seen, low flow error limit band 540a has a larger error limit value than normal flow error limit band 540b.

[0067] To meet the AGA11 standard, a Coriolis flow meter, such as the vibrometer 5 described above, may have an error rate that falls within the error limit band 540. However, because the low flow error limit band 540a has a larger error limit value than the normal flow error limit band 540b, many users choose not to operate the Coriolis meter at flow rates below the threshold flow rate Qt. As a result, the operating or effective turndown ratio of such a Coriolis flow meter is defined by the threshold flow rate Qt rather than the minimum flow rate Qmin. The error plot 530 may have a non-zero error rate for various reasons, including measurement bias associated with the reference zero flow value. For example, in equation [1] above, the zero flow time delay Δt0 may be an inaccurate zero flow value for the Coriolis flow meter. As a result, the measured flow rate

number

[0068] 5, error plot 530 may be improved by reducing the error rate represented by error plot 530. For example, error plot 530 may be shifted closer to the zero error axis by reducing the measurement bias caused by reference zero flow value 422. Additionally, other routines, such as calibration to determine FCF, may compensate for nonlinear contributions to error plot 530 at low flow rates. Thus, by shifting and flattening error plot 530, error plot 530 may be within normal flow error limit band 540b up to the minimum flow rate Qmin. As a result, a narrower error limit band may be used for flow rates between threshold flow rate Qt and minimum flow rate Qmin.

[0069] Measurement bias associated with a reference zero flow value can be removed by performing a zero calibration, which may be performed in the field by isolating the vibrometer 5 and performing a zero flow value calibration, see FIG. 1 . More specifically, the vibrometer 5 may be fluidically isolated such that the flow through the vibrometer 5 is zero, and therefore the measured zero flow value may be assumed to represent zero flow.

[0070] The difference between the measured zero flow value and the reference zero flow value may be proportional to the measurement bias caused by the erroneous reference zero flow value. To compensate for this measurement bias, the newly measured zero flow value may replace the reference zero flow value that may be stored in the meter electronics 20. However, as can be appreciated, the measured zero flow value may not be completely accurate. The following describes a method for determining that the measured zero flow value is a reliable zero flow value and therefore an accurate measurement of the zero flow value of the sensor assembly 10.

[0071] FIG. 6 illustrates a zero verification graph 600 showing the zero verification of the vibrometer 5. As shown in FIG. 6, the zero verification graph 600 includes a sample axis 610 and a zero flow value axis 620. The sample axis 610 is unitless but is shown as being in the time domain. Thus, each division on the sample axis 610 represents a sample time. The zero flow value axis 620 is shown as being represented in terms of a time delay Δt in units of time, although any suitable zero flow value, such as a phase difference, may be used. The units of the zero flow value axis 620 may be nanoseconds, although any suitable units, such as phase or angle-related units, may be used.

[0072] The zero verification graph 600 also shows a reference zero flow value 630 and a corresponding zero stability value 640. The zero stability value 640 is shown as a tolerance range around the reference zero flow value 630. The zero stability value 640 represents a zero verification criterion that may be a first zero verification criterion. In other words, if all measured zero flow values ​​fall within a band representing the zero stability value 640, the vibrometer 5 may be considered suitable for a first application associated with the first zero verification criterion. The first zero verification criterion may be associated with liquid measurements in uncustodial transfers.

[0073] The zero verification graph 600 also includes a zero flow value measurement 650, represented by a circular dot. The zero flow value measurement 650 may represent a zero flow value measurement made as described above with reference to FIG. 1. As can be seen, the zero flow value measurement 650 is consistently greater than the reference zero flow value 630. Thus, the zero flow value measurement 650 indicates that the reference zero flow value 630 may cause measurement bias in flow measurements made according to equation [1] above. Also shown is a mean 650a and confidence interval 650b, described in more detail below, determined from the zero flow value measurement 650.

[0074] The bias indicator may prove that the difference between the reference zero flow value 630 and the measured zero flow value 650 is due to an inaccuracy in the reference zero flow value 630. The bias indicator for the reference zero flow value 630 may consist of any one or more values ​​that indicate that the new zero flow value may reduce or eliminate measurement bias in the flow measurement caused by the reference zero flow value 630. The following description provides examples of bias indicators for the reference zero flow value 630.

[0075] The sign ratio is the ratio of the number of positive or negative values ​​or signs to the total number of values. The sign ratio may be referred to as a positive sign ratio if the counted signs are positive, or as a negative sign ratio if the counted signs are negative. As shown in FIG. 6 , the multiple differences between the measured zero flow value 650 and the reference zero flow value 630 are all positive values. Therefore, the positive sign ratio of the multiple differences is 100%. The negative sign ratio is 0%. If any sign ratio is greater than the bias indicator confidence threshold, the average value determined from the measured zero flow value 650 may be used as the new reference zero flow value to reduce or eliminate measurement bias caused by an inaccurate reference zero flow value 630. Additionally or alternatively, the new reference zero flow value may be determined by performing a zero calibration.

[0076] As an example, the bias indicator confidence threshold for the sign ratio may be a predetermined value of 75%. The measured zero flow values ​​650 are all greater than the reference zero flow value 630. Thus, as described above, the sign ratios of multiple differences between the measured zero flow values ​​650 and the reference zero flow value 630 are 100% positive. This is greater than 75%, and therefore the average value 650a calculated from the measured zero flow values ​​650 may be used as the reference zero flow value to reduce or eliminate the measurement bias caused by the reference zero flow value 630.

[0077] Statistical methods that calculate the probability of an outcome can be used to calculate the bias indicator of a vibrometer. For example, P and T statistics can be used to test whether a null hypothesis is met for a given data set. Rejecting the null hypothesis does not determine whether a condition exists in the vibrometer, but rather that the absence of the condition is false. For zero validation, the null hypothesis can be defined as "the current zero flow value is the same as the reference zero flow value." If this null hypothesis is rejected, it can be assumed that the current zero flow value is not the same as the reference zero flow value, and therefore the reference zero flow value causes measurement bias in the flow measurement.

[0078] As an example, in a t-test, the t-value may be calculated using the following formula:

number

number

number

[0079] As mentioned above, a t-test can be used to test the null hypothesis, which is the null test, where the sample mean

number

[0080] However, P values ​​may be difficult to calculate due to limited computing resources. For example, P values ​​may be calculated on a computer workstation with an operating system and statistical software, but may not be easily calculated on an embedded system. The meter electronics 20 described above may be an embedded system with limited computing resources.

[0081] For this purpose, a confidence interval that takes advantage of the limited computing resources of the meter electronics 20 may be used instead of the P-value. As a result, the confidence interval may be calculated using embedded code on the meter electronics 20. For example, the meter electronics 20 may have a current zero flow value and a zero standard deviation value stored in two registers. As can be understood, the above-mentioned t-value may be calculated using the current zero flow value by using the significance level α and the degrees of freedom. As an example, the significance level α may be set to 0.01, which is a 99% confidence level. The number of zero validation tests may be set as 10. Therefore, the degrees of freedom are determined to be 9. From the significance level α and the degrees of freedom, a two-tailed Student's t-value may be calculated using the Student's t-value function as follows:

number

[0082] The standard deviation of the measured zero flow values ​​can be determined. The standard error can also be calculated, which is defined as:

number

number

number

[0083] In the above example, a 99% confidence level may be used to calculate a confidence interval, which may be compared to a bias indicator confidence threshold. For example, the confidence interval may be used to test the null hypothesis by determining whether the confidence interval includes 0.0. If the confidence interval includes 0.0, the null hypothesis is not rejected, and zero validation indicates that the reference zero flow value does not cause measurement bias. If the confidence interval does not include 0.0, the null hypothesis is rejected, a zero validation failure may be signaled, the average of the zero flow value measurements 650 may be saved as the new reference zero flow value, a new calibration may be performed, etc. Thus, the confidence interval may be used to test the null hypothesis with a desired confidence level.

[0084] In addition to the confidence interval, a bias deadband can be defined around zero. This bias deadband in the t-test is a value around zero where small biases with small variations that would otherwise cause the confidence interval check to reject the hypothesis do not reject the hypothesis. Therefore, this bias deadband can be set to a value that reduces the number of false bias indications at the reference zero flow value.

[0085] In the example of a confidence interval compared to zero, the bias deadband is the range around zero, and if zero is not within the confidence interval but part of the bias deadband is within the confidence interval, the null hypothesis is not rejected. Mathematically, this test can be expressed as whether the mean zero flow value is less than the bias deadband. Or, using the nomenclature described above:

number

[0086] The bias deadband can be implemented alone or in combination with other deadbands. For example, the bias deadband can be implemented in conjunction with a variable deadband. In one example, variation =db bias / t student,99,8 The fluctuation deadband can be determined from variation is the fluctuation deadband. The fluctuation deadband may be compared to the zero flow value standard deviation to determine whether the null hypothesis should be rejected. In one example, the bias deadband may be compared as described above, and the fluctuation deadband may be compared to the zero flow value standard deviation as follows:

number

number

number

[0087] The reference zero flow value 630 may be updated, replaced, etc. when the bias indicator indicates that the reference zero flow value 630 may be replaced by a zero flow value that can reduce or eliminate the measurement bias caused by the reference zero flow value 630. Accordingly, the meter electronics 20 may be configured to update or replace the reference zero flow value 630 by, for example, storing an average value of the measured zero flow value 650, initiating a zero calibration routine to determine a new zero flow value, etc. The zero calibration routine to obtain a new reference zero flow value may be advantageous over the measured zero flow value 650 because the zero calibration routine may include additional quality control steps / features. Additionally, additional calibration steps, such as recalculation of the FCF, may be performed.

[0088] By reducing or eliminating measurement bias, along with other routines that reduce or eliminate nonlinear contributions at low flow rates, the improved error plot from error plot 530 shown in FIG. 5 may be within normal flow error limit band 540b, or a tighter error limit band, at flow rates down to the minimum flow rate Q. Thus, for applications with flow rates below the threshold flow rate Q, the zero verification criteria associated with normal flow error limit band 540b may be used. As can be appreciated, this can improve the effective turndown ratio of vibrometer 5 (i.e., increased to the ratio of maximum flow rate Q to minimum flow rate Q).

[0089] Certain applications with lower performance needs may be associated with more stringent zero verification criteria. An exemplary application with lower performance needs may be uncustodial transfer of liquids. Applications or processes with higher performance requirements may have associated zero verification criteria consisting, for example, of a zero stability value less than that used in the more stringent zero verification criteria described above. An exemplary high performance application may be custodial transfer of gas, such as custodial transfer of natural gas at a consumer site.

[0090] Stricter zero validation criteria may also include a bias indicator confidence threshold for the bias indicator of the reference zero flow value. For example, a central tendency value and variance value associated with the zero flow value measurement 650 may be determined and compared to the reference zero flow value. In one example, the central tendency value associated with the zero flow value measurement 650 may be the average of multiple differences between the zero flow value measurement 650 and the reference zero flow value. The variance value associated with the zero flow value measurement 650 may be, for example, a confidence interval 650b about the average 650a of multiple differences between the zero flow value measurement 650 and the reference zero flow value. As described above, the confidence interval 650b may be determined using a confidence level (e.g., 99%, 95%, etc.). The confidence interval 650b may be compared to a bias indicator confidence threshold, which may be zero or a dead band around zero in the null hypothesis t-test described above.

[0091] The zero verification criterion may be determined by meter electronics 20 based on the properties of the fluid. For example, the zero verification criterion scale may also be determined based on whether the fluid is a gas or a liquid. For example, if the zero stability value 640 is associated with an uncustodial transfer of a liquid, a stricter zero verification criterion for a custodial transfer of a gas may be calculated by scaling the zero stability value 640 by a zero verification criterion scale of, for example, 0.5, although any appropriate value may be employed. Other properties of the fluid may be used to determine the zero verification criterion scale, such as measured density.

[0092] More specifically, the density of the fluid contained in the vibrometer 5 may be measured and compared to a density value threshold. If the measured density is less than the density value threshold, a first zero verification criterion may be selected. If the measured density is greater than the density value threshold, a second zero verification criterion may be selected. The first zero verification criterion may be suitable for higher performance applications, and the second zero verification criterion may be suitable for lower performance applications. The density value threshold may be selected, entered, chosen, etc. by a user. More density value thresholds may be used. For example, there may be two or more density value thresholds defining density value ranges each associated with an additional zero verification criterion value. Thus, two or more zero verification criterions may be selected.

[0093] One of the zero verification threshold criteria may be stored in memory or scaled from another zero verification criteria. For example, referring to FIG. 5, error limit bands 540 have different values ​​based on the fluid flow rate. More specifically, low flow error limit band 540a has approximately twice the value of normal flow error limit band 540b. As can be appreciated, the zero verification criteria associated with low flow error limit band 540a may be more or less strict depending on the particular application, and the value of the zero verification criteria may be proportional to the ratio of low flow error limit band 540a to normal flow error limit band 540b.

[0094] 6 may be scaled (e.g., multiplied by a zero verification reference scale) depending on whether the vibrometer 5 is being used in a higher or lower performance application. For example, if the zero stability value 640 shown in FIG. 6 is associated with the low flow error limit band 540a, the zero stability value 640 may be multiplied by 0.5 in the meter electronics 20 to determine a smaller zero stability value near the reference zero flow value 630. By way of example, this may be tThis may be done with the goal of achieving accurate measurements within the normal flow error limit band 540b down to lower flow rates in order to improve flow rate to lower flow values ​​and thus extend the usable flow range of the meter in the application. As can be seen from Figure 5, the zero verification scale may depend on the expected flow rate of the fluid.

[0095] As described above, the zero validation criteria may consist of or include a bias index confidence threshold for a reference zero flow value, such as reference zero flow value 630. The bias index may be compared to the bias index confidence threshold. The bias index may be determined using, for example, a central tendency value and a variance value associated with the zero flow value measurement 650. As shown in FIG. 6, the central tendency value is the mean 650a and the variance value is the confidence interval 650b.

[0096] Additionally or alternatively, appropriate zero verification criteria may be selected based on the characteristics of the fluid within the vibrometer 5. For example, the zero verification criteria may be selected based on determining whether the application is a custody transfer of a gas. The selection criteria in this example may be determining whether the measured density is less than a gas density threshold and whether the vibrometer 5 should be used in a custody transfer. If both of these are true, a more stringent zero verification criteria may be selected.

[0097] As can be appreciated, the selection of the zero verification criteria may be automated. More specifically, the user need only store a value in meter electronics 20 that indicates that vibrometer 5 is being used in a custody transfer. Thus, meter electronics 20 may be configured to determine, for example, that vibrometer 5 is measuring liquid for a custody transfer, and thus, a smaller zero stability value around the reference zero flow value may be used during zero verification without determining a bias indicator for the reference zero flow value.

[0098] FIG. 7 illustrates a method 700 for selecting a zero verification criterion for performing zero verification of a vibrometer. As shown in FIG. 7, the method 700 determines a characteristic of a fluid in step 710. The fluid may be contained by a sensor assembly, such as the sensor assembly 10 described above. Containing the fluid may include isolating the fluid in the sensor assembly from a pipeline. The method 700 may select a zero verification criterion for the sensor assembly in step 720 based on the characteristic of the fluid. The zero verification criterion may be used to verify the sensor assembly for measuring the fluid.

[0099] Determining a characteristic of the fluid may include determining at least one of the density and phase of the fluid. Determining the phase of the fluid may include determining a parameter of the fluid and determining the phase of the fluid based on the parameter of the fluid. Density may be a parameter (or characteristic) of the fluid. Thus, method 700 may select a zero verification criterion based on a parameter of the fluid (e.g., density, frequency, mass flow rate, etc.) or the phase of the fluid. Determining the phase of the fluid may include determining that the phase of the fluid is one of a gas and a liquid and that the fluid is a single-phase fluid. Selecting a zero verification criterion for the sensor assembly based on a characteristic of the fluid may include selecting a zero verification criterion from two or more zero verification criteria. One of the two or more zero verification criteria may be associated with the fluid being a gas, and another of the two or more zero verification criteria is associated with the fluid being a liquid. Method 700 may also select a zero verification criterion based on a characteristic of the fluid and a parameter of the fluid. For example, method 700 may select a zero verification criterion based on whether the fluid is a liquid and whether the density of the fluid is greater than or less than a density value threshold.

[0100] Method 700 may be performed by meter electronics. Thus, meter electronics, such as meter electronics 20 described above, may include an interface, such as interface 401 described above, communicatively coupled to a sensor assembly, such as sensor assembly 10 described above, that contains a fluid. The sensor assembly containing the fluid may include a sensor assembly that is fluidly isolated from the pipeline, as described above with reference to FIG. 1. The meter electronics may also include a processing system, such as processing system 402 described above, communicatively coupled to interface 401. Processing system 402 may be configured to determine a characteristic of the fluid and select a zero verification reference value for the sensor assembly based on the characteristic of the fluid.

[0101] The processing system configured to determine a characteristic of a fluid comprises a processing system configured to determine at least one of a density and a phase of the fluid. The processing system configured to determine the phase of the fluid comprises a processing system configured to determine a parameter of the fluid and determine the phase of the fluid based on the parameter of the fluid. For example, the parameter of the fluid may be the density of the fluid. Thus, the processing system may be configured, for example, to select a zero validation criterion if the density is below a density threshold, determine a characteristic based on the density, select a zero validation criterion based on the characteristic, etc.

[0102] The processing system configured to determine the phase of the fluid may include a processing system configured to determine that the phase of the fluid is one of a gas and a liquid, and the fluid is a single-phase fluid. The processing system configured to select a zero verification criterion for the sensor assembly based on the characteristics of the fluid may include a processing system configured to select a zero verification criterion from two or more zero verification criteria. One of the two or more zero verification criteria may be associated with the fluid being a gas, and another of the two or more zero verification criteria may be associated with the fluid being a liquid. As can be appreciated, the meter electronics described above may be configured to perform methods such as those described below.

[0103] The vibrometer 5, meter electronics 20, and method 700 described above may select a zero verification criterion based on a characteristic of a fluid within the vibrometer 5, such as that contained within the sensor assembly 10 of the vibrometer 5. By selecting a zero verification criterion based on a characteristic of the fluid, the zero verification criterion may be more suited to a process involving the fluid. For example, a custodial transfer of a gas may require a relatively tighter tolerance for measurement than an uncustodial transfer of a fluid. Thus, a zero verification criterion selected for a custodial transfer of a gas may result in a measurement within an acceptable range.

[0104] The fluid properties may be determined in situ by the vibrometer 5. The fluid property used to select the zero verification criterion may be, for example, the density or phase of the fluid, determined in situ by the vibrometer 5 as described above. Thus, the vibrometer 5, and in particular the meter electronics 20, can accurately and automatically determine which zero verification criterion is appropriate for the fluid.

[0105] The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated for the present invention within the scope of this description. Indeed, those skilled in the art will recognize that certain elements of the above-described embodiments can be combined or excluded in various ways to form further embodiments, and that such further embodiments are within the scope and teachings of this description. It will also be apparent to those skilled in the art that the above-described embodiments can be combined in whole or in part to form additional embodiments within the scope and teachings of this description.

[0106] Thus, while specific embodiments have been described herein for illustrative purposes, various equivalent modifications are possible within the scope of this description, as those skilled in the relevant art will recognize. The teachings provided herein may be applied to other methods for selecting a zero verification criterion for zero verification of a vibrometer, vibrometer, and meter electronics, as well as the embodiments described above and illustrated in the accompanying drawings. The scope of the above-described embodiments should therefore be determined from the following claims.

Claims

1. 1. A meter electronics (20) for selecting a zero verification criterion for performing a zero verification of a vibrometer (5), comprising: an interface (401) communicatively coupled to a sensor assembly (10) containing a fluid; a processing system (402) communicatively coupled to the interface (401), Determine the properties of the fluid; a processing system (402) configured to select a zero verification reference value for the sensor assembly (10) based on the fluid characteristics; meter electronics (20).

2. 10. The meter electronics of claim 1, wherein the processing system configured to determine a property of the fluid comprises the processing system configured to determine at least one of a density and a phase of the fluid.

3. 3. The meter electronics of claim 2, wherein the processing system configured to determine the phase of the fluid comprises the processing system configured to determine a parameter of the fluid and determine the phase of the fluid based on the parameter of the fluid.

4. 3. The meter electronics of claim 2, wherein the processing system configured to determine the phase of the fluid comprises the processing system configured to determine that the phase of the fluid is one of a gas and a liquid, and the fluid is a single-phase fluid.

5. 2. The meter electronics (20) of claim 1, wherein the processing system (402) configured to select the zero verification criterion for the sensor assembly (10) based on the characteristic of the fluid comprises the processing system (402) configured to select the zero verification criterion from two or more zero verification criteria.

6. 6. The meter electronics (20) of claim 5, wherein one of the two or more zero verification criteria is associated with the fluid being a gas and another of the two or more zero verification criteria is associated with the fluid being a liquid.

7. 1. A method for selecting a zero verification criterion for performing zero verification of a vibrometer, comprising: containing a fluid within the sensor assembly; Determining a property of the fluid; selecting a zero verification reference value for the sensor assembly based on the characteristic of the fluid; and A method comprising:

8. The method of claim 7 , wherein determining the property of the fluid includes determining at least one of a density and a phase of the fluid.

9. The method of claim 8 , wherein determining the phase of the fluid comprises determining a parameter of the fluid and determining the phase of the fluid based on the parameter of the fluid.

10. 9. The method of claim 8, wherein determining the phase of the fluid comprises determining that the phase of the fluid is one of a gas and a liquid, and wherein the fluid is a single-phase fluid.

11. The method of claim 7 , wherein selecting the zero verification criterion for the sensor assembly based on the characteristic of the fluid comprises selecting the zero verification criterion from two or more zero verification criterion.

12. 8. The method of claim 7, wherein one of the two or more zero verification criteria is associated with the fluid being a gas and another of the two or more zero verification criteria is associated with the fluid being a liquid.

13. A vibrometer (5) capable of selecting a zero verification criterion for performing zero verification, a sensor assembly (10) containing a fluid; 10. A meter electronics (20) communicatively coupled to the sensor assembly (10), the meter electronics (20) being as set forth in any one of claims 1 to 6. a vibration meter (5) comprising:

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