Specifications

Reference Manual
MHM-97408, Rev. 2
June 2008
CSI 9420
C-2
There are, however, a number of different methods for measuring and reporting
Overall Velocity, so it is important to ensure that the measurement conditions
are similar when trying to duplicate the value reported by the CSI 9420 with that
of a handheld. The CSI 9420 uses ISO 10816, which defines a measurement
bandwidth of 2 Hz to 1 kHz. The ISO 10816 general fault levels at various
turning speeds are depicted graphically in the figure below.
Figure C-2. General Fault levels
Depending on the type of machine being monitored, the values shown in this
graph should be multiplied by the service factors given in the following table:
Table C-1. Service Factor
multiplier
It is important to note that the Overall Velocity thresholds in the graph are for
root-mean-square (RMS) velocity in units of inches per second. Particularly in
digital acquisition systems, it is customary to make the measurement and do the
calculation with RMS quantities. While it is accepted practice in the industry to
convert between RMS and peak values using the well-known 1.4142
conversion factor, it is not technically correct to do so except for a pure
sinusoidal waveform. For this reason the CSI 9420 measures, calculates, and
reports Overall Velocity in RMS, and it is necessary to multiply by 1.4142 to get
the corresponding peak levels if this is the preferred format.
The default levels in the CSI 9420 for ADVISE, MAINT, and FAILED alerts are
0.14 in/sec RMS, 0.35 in/sec RMS and 1.0 in/sec RMS, respectively.
Machinery Type Service Factor
Single-stage Centrifugal Pump, Electric Motors, Fans 1.0
Non-critical Chemical Processing Equipment 1.0
Turbine, Turbine Generator, Centrifugal Compressor 1.6
Miscellaneous Equipment 2.0