Standards For Vibration Measurements - Adash 4900 Vibrio III Manual

ADASH Ltd. Adash 4900 – Vibrio III

Standards for vibration measurements

Standards using is occasional topic in vibration diagnostics. Because there are a lot of different types
of machines it is impossible to determine the critical limits of vibrations for wide range of machines. Its
reliability would be low then. It would happened the decommissioning and repair machines, which do
not require it. On the other hand there would be unacceptable breakdowns, because measured values
could be high but not exceeded the limit. The standards should be determined for a narrow range of
machines.
A4900 Vibrio III contains Adash limit values. They are not rewritten from any existing standards. It's a
result of 20 years of Adash engineering team experiences. It's difficult to invent critical value definition
which would be simple (that means not many parameters such as speed, power, bearing type,
machine type and so on) and reliable.
On the figures below is clear how we derived limit values. Three levels of machine condition are
defined: GOOD, ALERT (Machines lays in this range are not acceptable for a long period operation,
they could be operated till time when could be repaired) and DANGER (Vibration values in this range
are considered as very dangerous an they can cause a damage of the machine). The corresponding
colors are taken from traffic semaphore - green, amber and red.
GOOD state is the space up to the yellow line that means operation without restriction. The space
above yellow but under red line is an ALERT state. Possible to operate the machine but have to be
more checked. It's necessary to determine the source of worse condition and plan repair (for instance
change the bearing) or maintenance (balancing, alignment). The space above red line is an DANGER
state and the machine should not be operated. First figure contains the values for overall machine
condition and you search unbalance, misalignment, and mechanical looseness above all. They are
called "overall" because we can measure them on most of the measuring points. Second figure
contains the limit values of a roller bearing condition. This state is local and can be measured only on
appropriate bearing house.
Work with figures is simple. It's necessary to know the speed. Instrument determines it automatically
or user can enter it manually. On the bottom horizontal axis you should find the point which
corresponds with speed. Above this point you will find an intersection with orange and red graph.
Projections to the vertical axis will determine limit values for amber or red state. If the measured value
is lower than amber the state is GOOD – green. If the value is above amber but under red then the
state is ALERT – amber. If the value is higher then red graph then the state is DANGER – red.
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