Refer to Example 21. 8. There are additional methods other than the two presented for increasing the NPSH in order to avoid pump cavitation. For the following situations, sketch the \(\mathrm{NPSH}_{A}\) curve on Figure 21. 9, keeping head at \(2 \mathrm{~m}\) and keeping the flowrate constant. Identify the operating point on the \(\mathrm{NPSH}_{A}\) curve in order to determine whether \(\mathrm{NPSH}_{A}>\mathrm{NPSH}_{R}\).

Figure 21.9

a. The diameter of the suction line can be increased. Examine the effect of increasing the diameter of the suction line to 1. 25 -in schedule 80 .

b. The temperature of the toluene can be decreased. Examine the effect of decreasing the temperature of the toluene to \(40^{\circ} \mathrm{C}\) using the original pipe.

Data from example 21.8

Transcribed Image Text:

NPSH (kPa) NPSH (kPa) 1.2 1.0 0.8 0.6 0.4 0.2 Region of acceptable operation NPSHR Unacceptable operation due to cavitation 0.0 1.2 1.0 0.8 90 0.6 0.4 0.2 0 2 Velocity, v (m/s) 1* sch 40, h=3 m. 55C NPSHA curves 6 1" sch 40, h=2 m, 55C NPSHA 0.0 0 2 6 8 8