Page 26 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Introduction to Vibrations

(1 × rpm) will be important in determining both conditions of
unbalance and misalignment. Two and three times operating
speed should also be recorded. Note that a vibration analyzer with
a filter is required to isolate these frequencies.
A filter out reading should always be recorded, to assure the
filter in readings capture all the frequencies that sum to the filter
out reading. In addition, the filter out reading is used to determine
the severity of the vibration.
Prior to providing another example, the criticality of equip-
ment needs to be discussed. There are certain pieces of equipment
within a facility that demand more attention than others.
The amount of effort spent on any given piece of equipment
will be directly dependent upon its criticality factor. Although
each facility will need to build criteria of their own, the following
illustrates how to categorize equipment.

IDENTIFYING CRITICAL EQUIPMENT

When surveying a facility to determine the extent of a predic-
tive maintenance program to be implemented on an on-going
basis, one important factor is determining the criticality of equip-
ment. The prioritization of equipment will assure the proper focus
on critical items and further assure that maintenance monies are
wisely spent.
To evaluate each piece of equipment within the facility, the
following chart can be used. Assign a value to each category based
on the specific requirements of the individual company. Add the
points scored by each piece of equipment and list them in de-
scending order. You have now established a criticality list.
It is important that some base line be established as a refer-
ence point. That is, all equipment should be surveyed and their
basic maintenance condition established. This provides the overall
maintenance condition of the facility, and can assist in preparing
a maintenance budget.
During the preliminary maintenance audit, mechanical and
electrical condition is noted as well as performance data. As an