Output performance: Analogue output accuracy check. Pulse output accuracy check.

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1 An insight into the reasons for verification: Confidence in ongoing performance, regulatory requirements, maintaining process quality. Calibration: The comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Usually carried out before a device is put into service. Verification: The process of establishing the truth, accuracy or validity of something. Periodic in-situ verifications will help to provide confidence that the meter is maintaining its specified performance during its operating life. 1

2 Overview of the methods used to verify electromagnetic flow meters until now. What parameters that influence performance can be verified in-situ? Faradays Law applied to an electromagnetic flow sensor. When conductor of length L moves with velocity V through a magnetic field B, a voltage Ui is induced in the conductor. Ui = L x B x V L is the distance between the measuring electrodes and B is designed to be constant. Parameters checked by today s verification devices / systems; or can be checked manually using conventional test equipment. Characteristics of the sensor coils: Fingerprint and Signature are terms used to describe the magnetic field strength boost time or time shot. Coil resistance. Coil insulation from ground. Coil voltage & current. Electrode circuit integrity: Electrode circuit resistance. Insulation test values to identify unwanted signals in the measurement circuit. 2

3 Overview of the methods used to verify electromagnetic flow meters until now. What parameters that influence performance can be verified in-situ? Verification checks on the transmitter. Reference signals are used to simulate measured values. Basic transmitter functionality: Confirmation of accurate instantaneous flow and total flow values. Transmitter gain, linearity & zero point checks. Output performance: Analogue output accuracy check. Pulse output accuracy check. 3

4 Overview of the methods used to verify electromagnetic flow meters until now. An ongoing debate: Internal verification or verification with external devices? External devices in use for around 20 years. Internal verification available in newer devices. Both methods are offered and both are valid. Likely to be that way for the foreseeable future. Provides choice for the user. Certificates provided by both methods. External device verification: Multiple reference circuits generate independent signals to the meter under test. Traceable annual calibration. Requires service technician. Internal verification: Continuous reporting of meter status. Can be remotely activated. Some tests are still made on demand. Sometimes requires additional test equipment. Uses internal factory traceable references. 4

5 Overview of the methods used to verify electromagnetic flow meters until now. Reference to international standards and approvals. Checking functions defined in OIML R49 typically included in battery powered meters Type P, permanent automatic checking facility that occurs at each measurement cycle Coil current test * Preamplifier test * Empty Pipe test * Flow overload Pulse overload Type I, Intermittent automatic checking facility that occurs at certain time intervals Checksum calculation (10 min. interval on totalizer checksum) Insulation test (minimum 24 hour interval) Battery capacity check (4 hours interval) Qualification certificate can be generated remotely via wireless communication 5

6 Introduction to emerging verification solutions. Further implementation of digitalization Improved built-in instrument diagnostics Flow comparison using clamp-on meter in series Intelligent fault descriptions more specific failure reporting, e.g. build up in the flow sensor Condition monitoring and preventative maintenance can be carried out by intelligent applications running in the secure data environment (cloud based or on premises) - separate from the conventional process control system. Cloud Operation Service Performance Monitoring Asset Life List Calibration & verification Management. Improve performance, reduce unplanned downtime Performance based services Maintenance planning Trend analysis of diagnostic data to predict application changes. Reduce maintenance and service costs 6

7 Example - Coriolis verification & flow comparison ID FTXXX Driver Current (ma) 12.8 Process Area TEST Pickup 1 signal (mv) 87.9 Diagnostics Name ADDITIVE Pickup 2 signal (mv) 86.8 Fluid Methanol/Water Tube frequency (Hz) Density kg/m3 797 Checked No Viscosity cst 45degC Value n/a Temp degc 46 Zero Adjusted No Flow Sensor Type Mass 2100 Offset, as seen (kg/hr) Size Di40 New Offset (kg/hr) n/a Diagnostic result: all values as expected. Pending errors: none Probability of linearity errors: very low (< 10%). Clamp-on comparison average result: 5.0% Recommendation: carry out zero check

8 Review of main factors affecting the installed accuracy of electromagnetic meters. 1. Maintaining a completely full flow sensor achieved by correct positioning in the pipe work and avoiding aeration. 2. Uniform flow (velocity) profile achieved by installing in a straight run of pipe work. 3. Possible build-up of solids inside the Magflo sensor; effectively reducing the bore of the sensor. 4. Stability of the electromagnetic field indicated by Fingerprint to verificator Boost Test comparison. 5. Measuring (electrode) circuit insulation quality, i.e. ability to reject unwanted signals and noise indicated by verificator insulation test. 6. Transmitter functionality and output accuracy indicated by the verificator transmitter test. Purpose of verification is to provide a high confidence level that factors 4, 5 and 6 are very close to original factory parameters. Tolerance levels to achieve a pass result for each test are very small. Typically, if all tests are passed, total measurement error due to factors 4, 5 and 6 will be less than +/- 1%. Factors 1, 2 and 3, if not followed correctly, can introduce significant measurement errors (e.g. 2 to 10 percent). Ideally, the installation conditions should closely follow independent guidelines, e.g. MCERTS. D Ronson Flow Product Manager Siemens UK 8