Aug. 1, 1925 
Tests of Deep-Well Turbine Pumps 
241 
to 134 feet for the average speed of 898 revolutions per minute. 
The stability of the operation of the pump between these limits is 
due to the balancing effect of the friction in the discharge pipe. 
As the head lowers, the capacity increases until a point is reached 
where the control-gate valve is wide open. At this point the dis¬ 
charge is maximum at 1,210 gallons per minute. The head would 
have been zero at this point of opening of the gate valve if the pump 
had been discharging into the air instead of raising the water high 
enough to pass 
through the measur¬ 
ing weir. Under such 
conditions, with zero 
head, no useful work 
would have been per¬ 
formed by the pump. 
130, 
120 
no 
100 
70 
60 
40 
& 
7 
r 
* 
% 
* 
: 910 
a 
Speed 
Lg00 
390 
VO 
r ■■ q 
u 
EFFICIENCY CURVE 
With no flow from 
the pump at the start, 
no useful work is being 
done by the pump, ^ 90 |——— \-/-\ —————V5H—ft——iso 
and hence the effi¬ 
ciency or ratio of out¬ 
put to input of power 
is zero. The efficiency 
curve therefore starts 
at zero. As the gate 
is opened, the capacity 
becomes greater and 
the efficiency in¬ 
creases very rapidly 
until a point of maxi- so, 
mum efficiency of 65.4 
per cent is reached. 
At this point the ca- q 200 
pacity is 775 gallons 
per minute. When FlG - 
the maximum capac¬ 
ity is reached the head is zero, with no useful work being done by 
the pump, and the efficiency also is zero. 
A point of interest in connection with this curve is that for a given 
efficiency there are two heads with their respective capacities. For 
example: With an efficiency of 60 per cent, the corresponding heads 
are 127 feet and 78 feet, with capacities of 510 and 985 gallons per 
minute, respectively. The data show a wide range of heads and 
capacities for efficiencies of 60 per cent or greater. By referring to 
Figure 9, the range of heads and capacities may be noted for various 
efficiencies of 40 per cent and over. 
80 
a 
7o| 
$ 
60 § 
40 
1 
301 
I 
I 
zok 
I 
10 § 
J 
400 600 800 
Gallons per Minute 
1000 
1200 
-Characteristic curves, pump No. 1,3-stage, 24-inch diameter, 
average speed 898 r. p. m. 
BRAKE-HORSEPOWER CURVE 
From this curve the size of prime mover to select can be deter¬ 
mined, and the load which will be carried for any given seUof con- 
60304—25f-4 
