50 7000

11,000 12,000

FIGURE 45 Influence of the design value of suction specific speed S on the flow rate QSR below which suction recirculation occurs. 2500 < ns < 10,000; (0.91 < Hs < 3.66) for single-suction or one side of a double-suction impeller. The ordinate is Qsr/Qsep in percent. (To obtain H55, divide s by 2733.)

up to 2500 (0.915) specific speed, and Figure 45 shows the same relation for pumps up to 10,000 (3.659) specific speed.

Despite the existence of suction and discharge recirculation, the mechanical response of the pump will not be serious unless the energy level is high. In other words, most pumps can indeed be operated at Q < QSR. The minimum flow rate or simply "minimum flow" Qmin is quantified in Section 2.1. As energy level is increased, Qmin approaches QSR in the limit. Examples of the difference between Qmin and QSR are as follows: For water pumps rated at 2500 gpm (158 l/s) and 150 ft (45.7 m) total head or less, the minimum operating flows can be as low as 50% of the suction recirculation values shown for continuous operation and as low as 25% for intermittent operation. For hydrocarbons, the minimum operating flows can be as low as 60% of the suction recirculation values shown for continuous operation and as low as 25% for intermittent operation.51,52,53

Temperature Rise Under steady-state conditions, friction and the work of compression increase the temperature of the liquid as it flows from suction to discharge. A further temperature increase may arise from liquid returned to the pump suction through wearing rings, a balancing device, or a minimum-flow bypass line that protects the pump when operating at or near shutoff.

Assuming that all heat generated remains in the liquid, the temperature rise is gH X (1 - h)

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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