Reference, Installation, and Operations Manual

Section 2: Product overview

3-9000-743 Rev S

June 2013

 

 

 

Section 2: Product overview

2.1Description

The Daniel Ultrasonic Gas Flow Meter measures the flow of gas, especially natural gas, by measuring the difference in signal transit time with and against the gas flow across one or more measurement path(s). A signal transmitted in the flow direction travels faster than one transmitted against the flow direction. Each measurement path is defined by a transducer pair in which each transducer alternately acts as transmitter and receiver. The meter uses the transit time measurements and transducer location information to calculate the mean gas velocity.

The Daniel Ultrasonic Gas Flow Meter offers bi-directional measurement capability (due to meter symmetry) over a wide range of flow rates with no pressure loss. Accuracy, safety, reliability, and ease-of-use are some of the many benefits of Daniel Ultrasonic Gas Flow Meters.

Computer simulations of various gas velocity profiles demonstrate that four measurement

paths provide an optimum solution for measuring asymmetric flow. The Daniel SeniorSonicTM Meter (Models 3400 and 3422) utilizes four cross-bore, parallel-plane measurement paths to offer a high degree of accuracy, repeatability, and superior low-flow capabilities without the compromises associated with conventional technologies. These features make the

SeniorSonicTM Meter the best choice for custody transfer applications.

Daniel offers two JuniorSonicTM Meter models (3410 and 3420) for applications that are cost-sensitive and/or do not require custody-transfer levels of accuracy. Model 3410 utilizes one

measurement path; Model 3420 utilizes two measurement paths. Unlike the SeniorSonicTM Meter designs, the JuniorSonicTM design bounces the ultrasonic signal across the meter body.

Each transducer is angled 60° from horizontal (60o included angle). The path is often referred to as a bounce-path (as the signal is bounced off the meter body) or a centerline path (as it goes through the center-line of the meter body). The 3420 model’s two paths are configured at right angles to one another in a “bulls-eye” arrangement. The bounce-path method simplifies construction of the meter and makes the meter less susceptible to interference from pipeline liquids.

Since the JuniorSonicTM Gas Flow Meter utilizes center-line paths, an additional piece of information is needed to determine the average velocity of the moving gas (remember that not all gas is moving at the same velocity). A “flow profile correction factor”, sometimes called the Reynold's Number correction factor, is needed to correct the velocity measured along the path(s) to the correct average for the cross sectional area. (see Section 5.6.11 and

Equation 6-18for Reynolds correction information). This can be accomplished by either using a fixed value or more accurately by measuring pressure and temperature, and then applying an active correction to the measured transit times.

The dual-path configuration (3420 model) provides a more representative measurement of the entire flow profile than the single-path configuration (3410 model).

The Daniel Ultrasonic Flow Gas Meter’s U.L. safety listing is accomplished through a combination of an explosion-proof electronics enclosure, and intrinsically safe transducers. The transducers and transducer leads are designed for maximum safety in a Class 1, Division 1 area without need of further protection when installed in accordance with the field wiring diagram (Daniel P/N DE-21056, see Appendix I).

Description

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