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Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

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490 <strong>Centrifugal</strong> <strong>Pumps</strong>: <strong>Design</strong> <strong>and</strong> <strong>Application</strong><br />

Figure 18-45. Pressure correction for isothermal secant bulk modulus for petroleum<br />

fractions [50].<br />

The value of CP/C V for most hydraulic fluids is approximately 1.15.<br />

The isentropic tangent bulk modulus for common petroleum oils can be<br />

determin<strong>ed</strong> from the Figures 18-44 <strong>and</strong> 18-45 as follows:<br />

1. On Figure 18-44, enter the desir<strong>ed</strong> temperature on the horizontal<br />

scale <strong>and</strong> go to the proper specific gravity line to read the isothermal<br />

secant bulk modulus at the reference pressure of 20,000 psig.<br />

2. Enter the isothermal secant bulk modulus (value from Step 1) on<br />

Figure 18-45 on the vertical scale; proce<strong>ed</strong> horizontally to intersect<br />

the 20,000 psi reference pressure line; move vertically to the line<br />

corresponding to twice the desir<strong>ed</strong> pressure. Move horizontally to

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