Reference, Installation, and Operations Manual

Section 6: Meter operation

3-9000-743 Rev S

June 2013

 

 

 

6.1.8Calibration

The Daniel Mark III Ultrasonic Gas Flow Meter meter uses two calibration steps: “dry” calibration and “wet” calibration.

In this methodology, the “dry-calibration” values are set by Daniel at the factory and are not expected to be modified; the “wet-calibration” values are expected to be set as the result of a user flow calibration (if desired). These two calibration methods are explained in further detail below.

Dry calibration

The dry-calibration gas flow velocity is the result of applying a third-order polynomial equation to the average weighted gas flow velocity as shown in Equation 6-8.

Equation 6-8 Dry-calibration gas flow velocity

VDryCal = A0 + A1VAvgWtd + A2V2AvgWtd + A3V3AvgWtd

where

VDryCal

VAvgWtd

A0

A1

A2

A3

=dry-calibration gas flow velocity (m/s) (DryCalVel)

=average weighted gas flow velocity (m/s) (AvgWtdFlowVel)

=dry-calibration 0th order coefficient (m/s) (FwdA0 or RevA0)

=dry-calibration 1st order coefficient (dimensionless) (FwdA1 or RevA1)

=dry-calibration 2nd order coefficient (s/m) (FwdA2 or RevA2)

=dry-calibration 3rd order coefficient (s2/m2) (FwdA3 or RevA3)

Note that the meter provides two sets of dry calibration coefficients - one set for each flow direction.

Wet Calibration

The Daniel Mark III Ultrasonic Gas Flow Meter meter offers three selections for wet calibration: 12-point piece-wise linearization, a third-order polynomial, or none. The wet calibration method to use is selected via the CalMethod data point with “None” being the default value. The wet calibration gas flow velocity is calculated from the dry calibration gas flow velocity as shown in Equation 6-9.

Calibration

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