Appendix G. Glossary

Transit-Time— Flow measurement technique based on the principle that when ultrasonic pulses are transmitted through a moving liquid, the pulses that travel in the same direction as the fluid flow (downstream) travel slightly faster than the pulses that travel against the flow (upstream). When the liquid in the pipe is not flowing, the transit-time downstream equals the transit-time upstream. When the liquid is flowing, the transit-time downstream is less than the transit-time upstream. The difference between the downstream and upstream transit-times is proportional to the velocity of the flowing liquid, and its sign indicates the direction of flow.

Traverses — Number of times the ultrasonic signal crosses the pipe.

User Functions — User-defined mathematical equations for use with any measurement.

User Tables — User-defined tables of data for use with user functions.

Velocity Averaging — Parameter that averages a desired number of velocity measurements to smooth out or dampen noise in the system.

Watchdog Test — Option in the Service Menu that tests the watchdog timer circuit. If a software error causes the meter to stop responding, this circuit automatically resets the meter

Wave Snapshot — Option in the Service Menu that enables users to capture waveforms for downloading to a PC for analysis, or for simulating a flow measurement.

Wedge Angle — Angle of the transducer’s ultrasonic transmission in the transducer wedge.

Zero Cutoff — Parameter that causes velocity measurements less than the absolute value of the cutoff (either positive or negative values) to be reported as zero.

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PT878 specifications

The GE PT878 is a state-of-the-art portable ultrasonic flow meter designed for the precise measurement of liquid flow in various applications. As part of General Electric’s renowned instrumentation lineup, the PT878 combines innovative technology with user-friendly features, making it an invaluable tool for engineers, technicians, and plant operators.

One of the standout characteristics of the PT878 is its non-invasive measurement capability. The meter utilizes clamp-on transducer technology, allowing it to be installed on the exterior of the pipe, eliminating the need for invasive procedures which can disrupt the system or require pipe cutting. This non-contact approach not only simplifies installation but also enhances the device’s versatility, as it can be applied to a wide range of pipe sizes and materials.

The PT878 leverages advanced digital signal processing and sophisticated algorithms to provide accurate and reliable flow measurements. It operates using the time-of-flight method, whereby ultrasonic signals are sent and received through the fluid in the pipeline to determine the flow rate. This technology allows for remarkable precision, ensuring that operational efficiency can be maintained.

Moreover, the PT878 is equipped with features such as a bright, easy-to-read display, intuitive navigation, and robustness against harsh environmental conditions. Its compact and lightweight design enhances portability, making it suitable for field applications. The meter operates on battery power, providing a long-lasting solution for remote monitoring and temporary installations.

Another impressive aspect of the PT878 is its ability to measure not only water but also a variety of liquids, from hydrocarbons to chemicals. It supports multiple measurement modes, including volumetric flow and velocity, offering a level of flexibility that caters to diverse industrial needs.

In addition to flow measurement, the PT878 offers data logging capabilities, allowing users to store and analyze flow data over time. This function is vital for understanding trends, diagnosing issues, and optimizing system performance. Users can easily transfer data to computers for comprehensive analysis, enhancing operational insights.

With its combination of innovative technology, user-friendliness, and robust measurements, the GE PT878 ultrasonic flow meter stands out as a comprehensive solution for industries requiring reliable liquid flow measurement. Whether in a manufacturing plant, a water treatment facility, or any application requiring fluid monitoring, the PT878 delivers exceptional performance and accuracy.
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