Fast On-Demand Ground Monitoring

On-Demand cloud-based service adds ground vibration to noise and environmental monitoring using connected ground terminal.


he Sentinel On Demand service offered by environmental monitoring specialist, EMS Brüel & Kjær, has been available for

noise and meteorological monitoring instrumentation for the last four years. Now, the company is also offering access to the same cloud-based on- demand tool to organisations looking to perform ground vibration monitoring. The service uses hardware installed on site complete with a remote configuration and set-up service so that monitoring can begin as soon as the equipment is installed and alerts received when pre-configured alarm limits are breached. The combination of B&K’s Vibration

Monitoring Terminal (VMT) and the Sentinel On Demand service can be used for the protection of construction sites from structural damage and the assessment of human comfort around railway projects. It can also be used to ensure the correct operation of hospital MRI and other industrial imaging equipment.

VIBRATION MONITORING TERMINAL (VMT) The VMT is a device that continuously measures ground vibration in three axes. The measurements comply with ISEE (2 to 250 Hz), DIN 45669– 1 (1 to 315 Hz), DIN 45669– 1 (1 to 80 Hz) and ISO 2631. It has a dynamic range from 2 µm/s (VC-E) to over 300 mm/s ensuring full coverage of vibration velocity levels. The VMT has sensor conditioning, processing, storage, GPS and wireless communication and is housed in a rugged IP67 rated

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❱ ❱ Vibration Monitoring Terminals can be quickly and easily set up on construction and railway project sites for short term measurements and assessments

aluminium enclosure and can operate in ambient temperatures from –20 to +53°C, making it suitable for harsh environments. The VMT logs data at 1 second

intervals, creates periodic reports at intervals of between 1 second and 60 minutes and generates vibration alerts in real-time, based on user-configurable trigger levels. Hourly instrument status reports include the status of the battery, sensor check, count of measurements and wireless and GPS signal strengths. It is available with ground spikes and a surface mounting plate to ensure measurements are correct and valid.

VIBRATION EVENT ALERTS A variety of measurement parameters are available including velocity and acceleration in each axis, expressed as Peak, RMS and in SI (eg mm/s) or Imperial (eg in/s) units. The dominant frequency in Hz is calculated using either zero crossing frequencies or with FFT depending on the standard chosen. A wide range of measurement weightings can be selected depending on the measurement standard chosen. A “vibration event” occurs when

vibration levels exceed defined limits with any or all axes of measurement capable of being set to trigger an event. When triggered, the VMT automatically

records the waveform in each axis with a pre- and post-trigger period xto ensure the full waveform is captured.

ON-DEMAND REPORTING The VMT is equipped with antennas enabling it to be connected via a SIM card to a 2G, 3G, 4G or LTE cellular network. When the EMC Brüel & Kjær Sentinel On-Demand service is used, the unit automatically connects when it’s switched on. It then configures itself and starts delivering data. In this set-up, all control of the VMT is done remotely including setup, remote display, operation and reporting. Vibration alerts are generated within seconds of them occurring and visualised and disseminated by Sentinel. The VMT can be set up with different alert trigger levels for different times of the day, and the reports contain sufficient detail for reporting and cause investigation. Sentinel shows live vibration velocity

data which is updated every minute. To confirm data validity, a sensor check is made daily.

According to David Currie, Product

Manager for Sentinel, the on-demand service is proving popular with noise consultants and construction where short term measurements are used for planning purposes so the addition of vibration makes it more compelling.

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