dp pumps
the dynamics of water
low-NPSHr dpv & dph(s)i Prevent cavitation and pump failure
low-NPSHr unique
Cavitation is caused by too low suction
pressure, in relation to the internal resistan-
ce of the liquid in the pump and the vapor pressure of a liquid (the higher the temperature, the higher the vapor pressure). In case
Also with higher flows
of cavitation pump problems occur because
DP’s unique design allows for lower NPSHr overall,
of imploding ‘bubbles’ generating an inten-
but also extends the low NPSHr to higher flows
se shock wave. Life expectancy decreases
where conventional pumps normally see a sharp
because of deteriorating of the metal and
increase in NPSHr with resultant cavitation.
extra wear on moving parts due to imbalance and decreased cooling and lubricating
No increased motor power
properties of the cavitating liquid. Without
Although the low NPSHr impellers would normally
cavitation you are assured of a quiet and
require slightly more power than the standard impel-
long-lasting smooth pumping.
lers, there will be no requirements for increased motor power due to efficient rimming of the low NPSHr components.
DP has developed a specially designed low NPSHr impeller and bottom stage casing to
Low NPSHr impeller versus standard Impeller
create a pump range with significant lower
n Inlet
NPSHr values. Due to this low NPSHr design
n The
the pump can be used in a wider range of
n Impeller
applications where low suction pressure and/
n Modified
or high vapor pressure of the liquid normally
n Total
cause problems
be compensated by the adjusted
diameter of the impeller is larger impeller opening height is increased base plate has been reinforced vane design
height of the impeller is larger, this will
bottom casing n Hot
water (Boiler feed)
n Feed
from a (low) reservoir
n Little
to no space between the deaerator tank
and the pump n No
vented tanks available
dphi
2
dpvcf
dpvsf
dpv
design Low NPSHr impeller
Extended CFD calculation models have resul-
A pump with Low NPSHr impeller has the same
ted in a design with lower fluid velocities at the
height as the standard version and can easily
core of the impeller (shown in blue).
be exchanged.
0 12
Standard impeller
20
0
10
IM.gpm
40
US.gpm 20
30
40
60
0
50
0
20
US.gpm 20
40
60
80
40
IM.gpm
100
60
80 2900 rpm
2900 rpm
DPV 10 B Low NPSHr
DPV 15 B Low NPSHr
14
10 Förderhöhe TDH Hauteur Prevalenza Opvoerhoogte Altura
30
m 8
ft
Low NPSH
6
Förderhöhe TDH Hauteur Prevalenza Opvoerhoogte Altura
20
40
12 m 10
ft
8
Standard Low NPSH
Standard
0
2
m³/h
0
4
6 l/s
1
8
10
2
12
0
14
3
Standard
NPSH3%
2 Low NPSH
0 = 1000.0 kg/m³
0
2
m³/h
4
6
8
Fördermenge/Flow/Débit/Portata/Capaciteit/Caudal
10
12
14 20161450/0
m³/h
10
15 l/s
2
20
4
ft
= 1000.0 kg/m³
15
Standard
m
ft
2
0
0
25
25 6
4
10
m NPSH3%
0
4
4
5
Low NPSH
0
5
m³/h
10
15
Fördermenge/Flow/Débit/Portata/Capaciteit/Caudal
20
25 20161652/0
Low NPSHr option is available for DPV (C/S) and DPH(S)I 2, 4,6, 10 and 15 in both 50 and 60 Hz
3
0
dp pumps P.O. Box 28 2400 AA Alphen aan den Rijn Holland t +31 172 48 83 88 f +31 172 46 89 30 dp@dp-pumps.com www.dp-pumps.com
97013926/0717