Per AGA Report No. 9 — Multipath Transit-Time Measurement
AGA Report No. 9 Ultrasonic Flow Meter Calculator
Calculates gas flow rates using multipath transit-time ultrasonic measurement. Supports flow rate calculation from transit time data and meter diagnostic validation per AGA 9 guidelines.
Calculation Mode:
Meter Configuration
in
Internal diameter of meter spool piece
Operating Conditions
psig
°F
μs
tup — against flow direction
μs
tdown — with flow direction
Gas Properties
-
Natural gas: 0.55–0.70, Methane: 0.554
-
Typical: 0.85–1.00 for natural gas
-
Natural gas: 1.27–1.31, Methane: 1.31
ft/s
Optional — from gas chromatograph for SOS validation
Meter Data
ft/s
Average SOS reported by USM
ft/s
Calculated from gas chromatograph analysis
Diagnostic Parameters
-
Ratio of avg to center path velocity (typical 0.95–1.05)
-
Flow profile symmetry factor (ideal = 0)
%
Cross-pipe velocity component (<2% preferred)
%
Turbulence intensity (<5% typical)
dB
Average SNR across all paths (>30 dB preferred)
Flow Measurement Results
Flow Rate
-
MMSCFD
Flow Rate (Mcfh)-
Flow Rate (ACFH)-
Gas Velocity-
Speed of Sound (USM)-
Reynolds Number-
Profile Factor-
Measurement Uncertainty-
Mass Flow Rate-
SOS Validation
Diagnostic Results
SOS Deviation
-
%
SOS Measured (USM)-
SOS from GC-
Profile Factor-
Symmetry-
Crossflow-
Turbulence-
Signal-to-Noise-
Overall Health-
Transit-Time Flow Equation
V = (L / 2cosθ) × (tup − tdown) / (tup × tdown)
V = Average gas velocity along acoustic path
L = Acoustic path length
θ = Path angle from pipe axis
tup, tdown = Transit times upstream / downstream
Standards & References
AGA Report No. 9
Measurement of Gas by Multipath Ultrasonic Meters