Tech Note 9 - Virtual Meter Path Technology

Redundant USM check metering has been used by many gas pipeline companies as a method to identify if the primary measurement device is still measuring accurately. There are several different ways to accomplishing this. For the concept to work effectively, a flow conditioner, like the CPA 55E, is generally required to provide a stable and repeatable flow profile. One check metering method uses two meters in series with different path configurations to avoid “common-mode” profile sensitivity. The thinking is that two different path configurations will react differently if the profile is affected by changes in operating conditions. Another check metering solution available today uses a meter with a second set of electronics and one or more additional pairs of transducers. These additional transducers are typically installed in a location that will be sensitive to changes in flow profile.

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