3. Summary
There are many cases where, like pumps and compressors in the process industry, their normal
operation is quite indispensable for the smooth operation of whole equipment. If such machines
should be troubled, resulting in impossibility of operation, danger will be attended or products and
materials under manufacture will be damaged wastefully if whole equipment is not stopped
immediately. In addition to the above, the suspension of the whole equipment due to repairing of
the troubled machines will do immeasurable damage.
Investigating the causes of trouble of machines like pump and compressor, no trouble will be
caused suddenly while operating. The causes of trouble are the increase in play due to loosening of
screws or wear of machine parts, entry of foreign matter in the sliding section, wear of bearings,
spalls due to fatigue and poor lubrication etc. If left as they are, the trouble will become serious or
cause another trouble, resulting in impossibility of whole equipment usually. In such a case, if
abnormality can be detected at an early stage of trouble, the pump or compressor can be shifted to
spare units, resulting in enabling you to repair the trouble machine without stopping the operation
of
whole equipment.
Vibration is generated at normal operating state in the case of rotating and reciprocating
machines.
If these machines should be troubled, an abnormal vibration will be generated
overlapping with the normal vibration. Though different depending on the troubled position, the
abnormal vibration is generated as a vibration of irregular waveform of higher frequency than that
at normal operating condition. As trouble progresses, the frequency and amplitude will be increased.
Because of the amplitude of the abnormal vibration during earlyfailures is small, it is difficult to
detect
by conventional vibrometer. If the amplitude of the abnormal vibration should be detected
by such conventional vibrometer, trouble will have become considerably serious, resulting in
requiring a considerably a long repair time and a large amount of repair cost. The VD-10 is a
vibration detector which is quite different from vibrometer in the operating principle for detection
of abnormality. Then the VD-10 cannot show the continuous measuring value of vibration
acceleration. The vibration detector is used as an alarm generator against abnormal vibration. If
vibration acceleration due to abnormal vibration exceeds a set value, an alarm signal will be output
from the contact switch of the VD-10.
Generally, vibration acceleration of a machine is calculated by amplitude and frequency of the
