Sound and Vibration - NEBB

NEBB S & V PROCEDURAL STANDARDS SECTION 7
VIBRATION MEASUREMENT
PROCEDURES
NOTES:
a. Vibration measurements with an FFT analyzer, require definition of other measurement
parameters; such as type of averaging and measurement duration, maximum versus
average level, type of windowing and setup for narrowband. This should be included in
contract specifications but if this is not the case they need to be agreed upon and
confirmed prior to taking any vibration readings.
b. Oftentimes building vibration requires seismic grade, high sensitivity (10,000 or 1,000
mV/G) accelerometers capable of measuring low levels and down to low
frequencies(1 to 2 Hz). A general purpose accelerometer with a sensitivity of 100
mV/g or less, may be insufficient for building floor vibration measurements of low
vibration amplitude. Refer to Table 4.1 in Section 4 for proper selection of vibration
transducers for low level vibration measurements.
7.6 MEASUREMENT LOCATIONS
Measure and record vibration levels at all required equipment, equipment bases and on
building structure adjacent to the equipment. Record vibration acceleration, velocity, and/or
displacement; in the vertical (radial), horizontal (transverse) and axial (longitudinal) axes
(with respect to the equipment axis of rotation), or as per contract specifications.
7.6.1 MEASUREMENTS ON EQUIPMENT
Perform vibration measurements at equipment and record vibration levels in the vertical,
horizontal, and axial axes, where measurements can be performed safely. If direct access to
the bearing is not available, then measurements shall be taken as close as possible to the
shaft center line at the housing. Measurements shall be taken as indicated in the following
table:
Equipment Item Location
Pumps Pump Bearing Drive end and opposite
end
Pumps Motor bearing Drive end and opposite
end
Fans and HVAC Equipment with Fans Fan Bearing Drive end and opposite
end
Fans and HVAC Equipment with Fans Motor Bearing Drive end and opposite
end
Chillers and HVAC Equipment with
Compressor Drive end and opposite
Compressors
Chillers and HVAC Equipment with
Compressors
Bearing
Motor Bearing
end
Drive end and opposite
end
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