Over the past two decades, both the parallel chord concept and the reflection principle have been established in the gas metering market. The parallel chord concept refers to a system that involves ultrasonic sensors sitting opposite each other. The sensors send and receive ultrasonic signals simultaneously, and are aligned in parallel segments across the flowmeter.

Instead of having sensors directly opposite each other, the reflection principle involves two sensors on one side of the pipe and a reflector (like a mirror) on the opposite side, arranged in a ‘V’ shape configuration. The sensors and the reflector are still aligned in a chord; however the path length is increased by using a reflector, making the flow measurement more accurate.

Both concepts have advantages, but they also have downsides. In theory, a greater number of chords increases accuracy, yet in practice the number of chords is limited due to economic and practical concerns.

Krohne has combined both concepts in a single device, the Altosonic V12. The product’s ten reflection parallel chords in five planes enable precise and reliable measurement, while its two reflection chords also allow access to extra diagnostic functions.

The unique chord arrangement of the Altosonic V12 enables the product to generate diagnostic data for places where traditional ultrasonic meters gathered too little information or none at all. Using the reflection principle, the meter can generate data at the pipe wall itself. It also generates data in close proximity to the pipe wall, using the geometrical arrangement of the external chords; and, finally, generates data at the bottom of the pipe.

This data is gathered using a separate diagnostic chord. This extensive diagnostic data allows the Altosonic V12 to carry out self-monitoring, which sets a new standard in terms of performance monitoring.

Analysis of current data and trends in a system

Performance monitoring data is verified twice: once for current data and once for trend analysis. For current data analysis, error analysis is carried out in one second cycles in the ultrasonic meter itself. In addition, trend analysis is carried out in 24-hour cycles in the Krohne Care™ System. This analysis recognises long term process changes, such as the accumulation of dirt, and investigates whether possible contamination is affecting accuracy.

In addition to the trend data, Altosonic V12 stores important event data. This includes information about the factory inspection, high pressure calibration and commissioning, as well as periodical meter checks.

Performance monitoring allows maintenance at regular intervals to be replaced by maintenance determined by the condition of the equipment. This means that the interval between periodical high pressure calibrations can be systematically increased. This saves time, stress, staff and money.

Krohne was the first to separate fiscal data from diagnostic data in an ultrasonic gas flow meter used for custody transfer applications. Two separate signal outputs transmit diagnostic data directly to the user and to the Krohne Care™ web server, available in the third quarter of 2009. Meanwhile, the web server has all the Altosonic V12 status information required.

With the Altosonic V12, the user can receive information not only about the measuring instrument itself but also about the instrument’s application conditions. The system is based on the ’condition-based maintenance’ design whereby maintenance is performed only when required by process conditions.

Krohne processes the information in a database and informs the user as soon as any intervention is required. Krohne Care™ has a user-friendly graphic interface, which is easy to use. The Altosonic V12 is available in standard widths from DN100 to DN600. The flow meter is compatible with most commercial protocols and can therefore be used with any type of existing infrastructure.

Ease of integration

The Altosonic V12 is compatible with the installation lengths and data protocols of earlier leading ultrasonic meter manufacturers. After installation, the ‘plug and play’ electronics automatically run a self-test. Each Altosonic V12 is supplied with software to enable a laptop to communicate with the meter – making it possible for authorised personnel to monitor the meter and log data.