Page 242 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Be st Practice 3 .27 Compressor Best Practices
to us in the plant, such as DCS systems, etc. The important
point is to obtain the baseline and trends of data on a periodic
Define each major component
List condition monitoring parameters basis. When trending data, threshold points should also be de-
Obtain baseline data fined for each parameter that is trended. This means that when
Trend data the pre-established value of the parameter is exceeded, action
Establish threshold limits must be taken regarding problem analysis. Setting threshold
values at a standard percentage above the normal value is
recommended. Typically values are of the order of 25e30%
Fig 3.27.3 Component condition monitoring
above baseline values. However, these values must be defined
equipment. However, operations should be consulted to con- for each component based on experience. Figure 3.27.5 presents
firm when the unit is operating at rated or lined out conditions. trending data for a hydrodynamic journal bearing. All of the
Obtaining baseline information without conferring with opera- parameters noted in Figure 3.27.5 should be monitored to
tions is not recommended, since faulty information could be define the condition of this journal bearing.
obtained which could thus lead to erroneous conclusions in
predictive maintenance. Figure 3.27.4 states the basics of
a baseline condition. Specific machinery component and system
monitoring parameters and their limits

If you don't know where you started, you do not know where you are On the following pages is contained information concerning
going!
what parameters should be monitored for each major machinery
component to determine its condition. In addition, typical limits
Fig 3.27.4 Base line condition are noted for each component.
These limits represent the approximate point at which action
It is amazing to us how many times baseline conditions are should be planned for maintenance. They are not intended to
ignored. Please remember Figure 3.27.4, and make it a practice define shutdown values.
to obtain baseline conditions as soon as possible after start-up.
The rotor
Trending
Rotor condition defines the performance condition (energy and
efficiency) of the machine. Table 3.27.1 presents this value for
Trending is simply the practice of monitoring parameter con-
dition with time. Trending begins with baseline conditions, and a pump.
will continue until equipment shutdown. In modern day
thought, it is often conjectured that trending must be performed Radial bearings
by micro-processors and sophisticated control systems. This is Figures 3.27.6 and 3.27.7 present the facts concerning anti-
not necessary! Effective trending can be performed by periodic friction and hydrodynamic (sleeve) radial or journal bearing
manual observation of equipment, or using equipment available condition monitoring.

Fig 3.27.5 Trending data

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