Online Monitoring


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Pump with temporarily installed accelerometers, proximity probes, and tachometer for online monitoring of a vibration issue.

Pump with temporarily installed accelerometers, proximity probes, and tachometer for online monitoring of a vibration issue.

MSI performs online monitoring to help troubleshoot problems with rotating machinery. Often the best opportunity to diagnose issues is during transient events such as start-ups, shut-downs, load changes, or other variations in operating conditions. MSI routinely captures data from a variety of sensor types during these transient events, or during routine operation, to draw conclusions about machinery health and identify problem behavior.

The most commonly used sensor type is the accelerometer. These are typically mounted on bearing housings, machinery casings, and other key locations where operational forces interact with system components. MSI also uses proximity probes to capture shaft vibration and migration, either by tapping into existing instrumentation (e.g. Bently-Nevada) or by temporarily installing our own. Other sensors commonly used include tachometers to measure shaft speed; pressure transducers (static or dynamic), flow meters, or Pitot tubes to measure flow conditions; thermocouples; microphones; strain gages to measure shaft torque or casing/piping deformation; current clamps; and more.

Online Monitoring Measurement Equipment

Typical equipment used for online monitoring, including sensors, data acquisition hardware, and a laptop.

Our fleet of data acquisition equipment is capable of measuring up to hundreds of channels at sampling rates of up to 204.8 kS/s to capture frequencies up to 80 kHz. Data collection times can range from a few minutes to several months depending on the situation. We maintain an extensive fleet of sensors, including for specialty applications such as high temperature environments, submersed applications, extreme pressures, and toxic or corrosive conditions. If we don’t already have the instrumentation needed for your application, we’ll arrange to rent supplementary equipment.

Shaft orbit measured during online monitoring that confirms a resonant excitation of a lateral rocking mode, as evidenced by the double-circle trace. Shaft orbit plots are just one of many graphical displays used by MSI engineers and technicians to rapidly draw conclusions from sensor data during online monitoring.

Shaft orbit measured during online monitoring that confirms a resonant excitation of a lateral rocking mode, as evidenced by the double-circle trace. Shaft orbit plots are just one of many graphical displays used by MSI engineers and technicians to rapidly draw conclusions from sensor data during online monitoring.

MSI’s proprietary Sentry™ software provides for a variety of real-time graphical displays to assist our engineers and technicians in making diagnoses in the field. Waveform displays, spectrum analysis, trending, shaft orbit and centerlines, waterfall displays, and Bode plots are just some of the tools used by our staff during online monitoring.

Our expert engineers and technicians, combined with our state-of-the-art tools, can diagnose problems both routine both rare. While we routinely encounter the simple imbalance and misalignment issues, MSI specializes in solving the most challenging problems where overlapping faults may result in contradictory evidence in the data. We often combine online monitoring with other engineering tools such as experimental modal analysis (EMA), operating deflection shape (ODS) characterization, or finite element analysis (FEA) to successfully resolve problems in rotating machinery.

Please explore our case studies or contact an engineer to discuss your needs.