Environmental Engineering Reference
In-Depth Information
PUMPING EXAMPLES
Example 14.15
Problem: A pump must pump 4800 gpm against a total head of 80 ft. What horse-
power will be required to do the work?
Solution:
Flow (gpm)Head (ft)
3960
×
4800 gpm
×
3960
80 ft
whp
=
=
=
97 hp
Example 14.16
Problem: If a pump is to deliver 350 gpm of water against a total head of 60 ft, and
the pump has an efficiency of 85%, what horsepower must be supplied to the pump?
Solution:
Flow (gpm)Head (ft)
3960
×
350
gpm
×
60 ft
bhp
=
=
=
6.2 hp
×
Efficiency
3960
×
0.85
Example 14.17
Problem: The manual indicates that the output of a certain motor is 30 hp. How
much horsepower must be supplied to the motor if the motor is 90% efficient?
Solution:
mhp = bhp ÷ Motor efficiency = 30 hp ÷ 0.90 = 33.3 hp
Example 14.18
Problem: The water horsepower was calculated to be 15 hp. If the motor supplies the
pump with 20 hp, what must be the efficiency of the pump?
Solution:
Water horsepower
Bra
15 hp
20 hp
Percent pumpefficiency
=
×= ×=
100
100
75%
ke horsepower
Example 14.19
Problem: What is the overall efficiency if 50 hp is supplied to the motor and 28 hp
of work is accomplished?
Solution:
Water horsepower
28 hp
50 hp
Percent overall efficiency
=
×= ×=
100
100
56%
Motor horsepower
 
Search WWH ::




Custom Search