Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
2017 Western Regional Gas Conference
Bayview Ballroom 2
8/29/2017
9:00 – 9:45
Presenter: Dan Whaley
Company: Meter, Valve & Control, Inc
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
▪ Natural gas distribution
▪ Transfer and measuring stations for municipal and regional gas suppliers
▪ Measuring stations of industrial and commercial applications
▪ Applications where continuous gas supply must be ensured
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Operating PrincipleCrossing a river
• A boat crossing a river diagonally with the flow needs less
time than a boat crossing the river against the flow
• The stronger the current the faster the crossing with the
flow and the slower the crossing against it
• The difference between the two transit times depends
directly on the flow velocity
• Exactly this effect is exploited by the ultrasonic flow meter
Crossing a pipe by ultra sound
• The two diagonally opposed transducers function
alternatively as transmitters and receivers
• The sound signal emitted from Transducer A is accelerated
by the flow
• The sound signal emitted from Transducer B is slowed by
the flow
• The difference between the two transit times (T1 & T2) is
directly proportional to the gas velocity
• From the gas velocity, the volumetric flow can then be
calculated using cross sectional area.
Transducer B
Transducer A
Flow direction
Transit time
from A to B
(T1)
Transit time
from B to A
(T2)
Delta time
T = T2 - T1
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Operating Principle
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Typical Ultrasonic Meter Designs
Several meter designs are available today
Many diagnostic parameters are similar for all designs
Main difference in designs is analysis of velocity info
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Typical Ultrasonic Meter Designs
Path CPath A
Path A
Path B
Path B
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Flow Profile
• Good measurement is dependent on flow profile
• Typical requirements for upstream/downstream piping
with flow conditioning.
• Internal Flow Conditioning = No Upstream/Downstream
Piping Requirements
U-turn
Metering
section
Flow
conditioning
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics
Diagnostic parameters in USMs that are required by AGA 9:
• Average Gain Control (AGC) Levels
• Path Transit Times
• Average Axial Flow
• Speed of Sound (SOS) for each path
• Flow Velocities (VOG) for each path
• Average Speed of Sound
• Velocity Sampling Interval
• Averaging Time Interval
• Percentage of accepted pulses
• Status and/or measurement quality
• Alarm and failure indicatorsMeter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics - Gain
Gain? Can anyone tell me what it is?
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics - Gain
• Automatic operation in USMs
• Manufactures fire transducers with a fixed energy
• Gain is a measure of how much amplification is needed
• Amount of gain depends on several variables including:
• Metering pressure
• Gas velocity
• Meter size (path length)
• May increase due to contamination
• Gas composition (i.e.; Hydrogen vs. Natural Gas)
• Readings vary by manufacturer
• Contamination seldom causes gain to reach the maximumMeter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics - SNR
Signal to Noise? Can anyone tell me
what it is?
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics - SNR
• SNR is a measure of signal strength to noise
• Generally SNR is not used as much as others
• SNR becomes important when control valves are near
• At very high gas velocities, SNR will decrease
• Different manufactures have different methods of presenting
this information
• When the SNR gets low enough, performance will also decline
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics - SOS
Speed of Sound? Can anyone tell me what
it is?
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics - SOS
• Equation is similar to velocity calculation
• “Health” check for path velocities
• SOS by path is required by AGA 9
• SOS affect by gas composition, P&T, but not gas velocity!
• Can be calculated with AGA 10 or other algorithms
• If they do not agree, possibility of liquids, contamination or
poorly entered data.
• Can be checked versus theoretical values using GCMeter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics - Performance
Performance? Can anyone tell me what it
is?
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics - Performance
• Signal Quality
• Level of accepted pulses (displayed in percent)
• Reported by path
• 100% acceptance isn’t required for accurate measurement
• Pulses are rejected if they fail certain criteria
• The most important part of pulse detection is to insure we don’t
pick the wrong waveform peak and thus have a bad transit time
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics - Performance
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics In Action
• Software will automatically compare diagnostic
parameters. If within tolerance, meter will give an “all
good signal”
• If not in tolerance will give an indication as well
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics In Action
• All diagnostic data for each path is stored and can be
reviewed to determine the cause.
• Can account for accuracy changes.
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Diagnostics In Action
Meter, Valve & Control, Inc
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Verification
Meter, Valve & Control, Inc
• Self-Diagnostics
• SOS Verification
• Transfer Prover
Commercial/Industrial Ultrasonic Gas Meter
Operation & Diagnostics
Verification
Meter, Valve & Control, Inc
Questions? Comments?