Drivers efficiency

Fl = frame loss for motor-driven compressors only, values range 1.0-1.05 (note, this is not a driver efficiency factor). 

Figure 14-37 gives values that are suitable for design estimates of centrifugal-pump efficiencies. Because pump and driver efficiencies must both be considered when total power costs are determined, necessary design data on the efficiency of electric motors are presented in Fig. 14-38. 

Driver horsepower, HP = BHP/(driver efficiency) = HHP/(pump efficiency)(driver efficiency). 

Efficiency data of drivers are in Chapter 4 and of pumps in Chapter 7. For example, with 500 gpm, a pressure difference of 75psi, pump efficiency of 0.7, and driver efficiency of 0.9, the power requirement is 32.9 HP or 24.5 kw. 

Let us next look at a major European truck manufacturer. It has 20 000 employees and delivers 80 000 heavy trucks a year with a weight above 16 tonnes. The company has the ambition to be a world leader in terms of active and passive safety in vehicles. The company management s motives are commercial as well as ethical. Safety is a cornerstone in the company s marketing strategy. It is claimed that the safety features of the company s trucks reduce accident risk and increase driver efficiency. 

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