Emerson’s Trever Ball presented Smart Meter Verification Enhancements Improve Safety and Process Availability at the 2009 Emerson Exchange conference.
Trever began by defining terms. Calibration is performed at the factory. It establishes the relationship between flow and signal produced by the sensor. Validation confirms flow performance by comparing a primary flow standard to the sensor. Verification establishes confidence in performance by analysis of the secondary variables associated with flow. Many times these terms are used interchangeably. Also, frequently calibration or validation is done when only verification is needed.
During factory calibration, baseline measurements are performed in which the smart device can self-check against once operating in the field. For example, Micro Motion Coriolis meters check tube stiffness and Rosemount E-series magnetic flowmeters check against a magnetic field signature to perform ongoing verification.
Smart meter verification is verification on demand, whenever you want on demand or on a schedule. It provides diagnosis of the whole system including the sensor, drive, and signal processing. This verification process provides absolute confidence in measurement performance
For Micro Motion Coriolis Smart Meter verification, the Coriolis meter has no moving parts. Coating and corrosion can impact the stiffness of the meter tubes. Smart Meter verification measures the meter’s mechanical characteristics so when a change in the tube stiffness is detected, performance is checked to see if it remains within factory specifications.
Rosemount magnetic flowmeters also have no moving parts and has an expectation that the meter calibration will never change. Over time, the calibration may be impacted if there is a shift in the coils due to vibration, thermal cycling, etc. Smart Meter verification measures the sensor’s magnetic field strength characteristics, and when a change is detected, it determines whether the meter’s performance remains within factory specifications.
A final example Trever described was the Rosemount 8800 Vortex flowmeter. The vortex sensor is a piezo crystal, which provides a low-level voltage when it is flexed. Vortices in the flow cause the sensor to pulse. The vortex electronics take the frequency of these pulses to deliver a flow output.
Historically, vortex verification has been difficult. It’s become easier since properly functioning electronics can be verified by testing with a known frequency. The vortex sensor can be verified by measuring signal strength with a handheld device or via applications, such as AMS Device Manager software.
Trever closed his presentation with some quantified results of Smart Meter verification savings versus traditional maintenance and verification practices. Maintaining these flow devices within factory specification also improves plant availability, product quality, and reduces waste and rework.