Page 395 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Be st Practice 7 .7 Lube, Seal and Control Oil System Best Practices

Fig 7.7.4b Rotary pump data sheet (Courtesy of The American Petroleum Institute)

All specified pump operating conditions should be con- Pump differential head in Figure 7.7.7 is expressed in feet of
firmed so that they reflect the actual system requirements. A liquid and is determined by:
check list is presented in Figure 7.7.6. This step ensures that
the second part of the pump function definition will be met: Differential pump head ðftÞ

‘to supply the system fluid at the required pressure and flow
rate’. 2:311 ft of H 2 0 pump differential pressure ðpsiÞ
psi
As previously mentioned, there are two major classifications ¼
of pumps, and either can be used for auxiliary system duty: specific gravity
With this relationship it is very important to understand that
- Positive displacement pumps
- Dynamic pumps ‘head’ is energy. Referring back to Figure 7.7.7, we can see that
a positive displacement pump is a variable energy (head) device as
The definitions and characteristics of both are shown in opposed to a dynamic pump which is a fixed energy (head) device.
Figure 7.7.7. As the specific gravity of a liquid (the ratio of the weight of a given

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