PPV, shock, vibration and tilt
3 axis acceleration, shock, temperature, humidity, light and pressure
Ethernet-Based Portable Vibration Analysis and Monitoring System
8 dynamic input channels, expandable up to 56 channels • 4 tachometer channels for rotational measurements • High-speed Ethernet connection to the PC for continuous recording • Four eZ-Series software packages address a wide variety of vibration monitoring and analysis applications • TEDS support • 8 Digital I/O lines
Monitoring shock and vibration in the real word
The reason for monitoring shock and vibration is because of the potential adverse effects on buildings, their contents; or to monitor valuable products in transit; or for condition monitoring of rotating equipment. The sources of shock and vibration are very diverse ranging from construction works [piling, ground works, tunnelling, fracking, etc.], blasting, road traffic, other transportation modes, etc. Or in the cases of products in transit from transport or handling/mis handling.
Vibration monitoring standards
For structural monitoring, a large number of international standards document permitted or recommended levels. Some principal standards are:
To say that the standards require interpretation is an understatement and in many instances are littered with caveats along the lines of “ …the levels suggested …” or “… some data suggests..” !
Insurance requirements for monitoring vibration
Some major infrastructure companies have specified the circumstances under which monitoring is required for works in proximity to their installations, eg
Remote monitoring of Shock and Vibration is increasingly common in tender specifications for major works, and vibration and shock monitoring is referred to in Eurocodes.
Peak Particle Velocity (PPV)
For impact on structures the principle measure of interest to engineers and consultants is PPV – Peak Particle Velocity. PPV is defined as the maximum instantaneous peak of the vibration signal, measured in m/s or mm/s [or inches/s in the USA]. For impact on humans PPV is not helpful as it takes some time for the human body to respond to vibration signals. Because the net average vibration signal is zero the root mean square[RMS] is used to describe a smoothed amplitude. These are shown graphically in Figure 7-2 [courtesy of ntl.bts.gov/data/rail05/ch7]
Most of our customers are interested in PPV, monitoring impact on structures or buildings. According to several of the standards the potential for structural damage is correlated to PPV [mm/s] within certain frequency bands: