Water Treatment Processes - Mathematics and Statistics for the Environment - page 609

And then the water horsepower can be calculated:

179.7 ft × 800 gpm × 8.34 lb/g al

Water horsepower = = 36

33,000 ft-lb/min

■ EXAMPLE 23.12
Problem: A deep-well vertical turbine pump delivers 600 gpm. If the lab head is 185 feet and the
bowl efficiency is 84%, what is the bowl horsepower?

Solution:

Bowl head (ft)Capacity (gp × m)

Bowl efficiency 100

Bowl horsepower =

3960 × (

)

185 ft × 600 gpm 185 ft × 600 gpm

=

) =

= 33 . 4

× (

3960 84 0 100 . 3960 × 084 .

■ EXAMPLE 23.13
Problem: The bowl bhp is 51.8 bhp. If the 1-inch diameter shaft is 170 ft long and is rotating at 960
rpm with a shaft fiction loss of 0.29 hp loss per 100 ft, what is the field bhp?

Solution: Before field bhp can be calculated, the shaft loss must be factored in as follows:

( 0.29 hp loss ) × ( 170 ft )

= 05 .

100

Now determine the field bhp:

Field bhp = Bowl bhp + Shaft Loss (hp) = 51.8 bhp + 0.5 hp = 52.3 bhp

■ EXAMPLE 23.14
Problem: The field horsepower for a deep-well turbine pump is 62 bhp. If the thrust bearing loss is
0.5 hp and the motor efficiency is 88%, what is the motor input horsepower?

Solution:

Field(total) bhp
Mot

62 bhp 0.5 hp

0.88

+

Motorinput horsepower = = = 71 mhp

or efficiency 100

When we speak of the efficiency. of any machine, we are speaking primarily of a comparison
of what is put out by the machine (e.g., energy output) compared to its input (e.g., energy input).
Horsepower efficiency, for example, is a comparison of horsepower output of the unit or system
with horsepower input to that unit or system—the unit's efficiency. With regard to vertical turbine
pumps, there are four types of efficiencies considered with vertical turbine pumps:

• Bowl eficiency
• Field eficiency
• Motor eficiency
• Overall eficiency