Brochure

H
1
H
'
2
H
2
H
loss,friction,1
H
loss,friction, 2
H
S
'
1
H
'
1
S
1
S
2
S
'
2
102102
Figure 6.6: Draft of pump test on
a piping.
6.2.4 Calculation of head
The head can be calculated when flow, pressure, fluid
type, temperature and geometric sizes such as pipe
diameter, distances and heights are known. The total
head from flange to flange is defined by the following
equation:
(6.1)
(6.2)
(6.3)
(6.4)
(6.5)
12
HHH − =
( ) ( )
12
''
loss, friction,2 loss, friction,1
HHHHH − − +=
Dynamic pressureStatic pressure
Geodetic pressure
g
UU
g
pp
zzH
⋅
−
+
⋅
−
+ − =
2
2
1
2
212
12
ρ






−
⋅
+








+
⋅
+
−






+
⋅
+








+
⋅
+ =
2
1
1
1
1
2
2
2
2
2
2
'
'
'
'
2
'
'
'
'
loss, friction,1 M
M
loss, friction, 2 M
M
H
g
U
z
g
p
z
H
g
U
z
g
p
zH
ρ
ρ
g
p
Hz
g
Vpp
NPSH
vapour
loss, friction, geo
barstat,in
A
⋅
− − +
⋅
⋅ ⋅ + +
=
ρρ
ρ
2
1
5.0
Figure 6.6 shows where the measurements are made.
The pressure outlets and the matching heads are marked
with a ( ’ ). The pressure outlets are thus found in the po-
sitions S’
1
and S’
2
and the expression for the total head
is therefore:
(6.1)
(6.2)
(6.3)
(6.4)
(6.5)
12
HHH − =
( ) ( )
12
''
loss, friction,2 loss, friction,1
HHHHH − − +=
Dynamic pressureStatic pressure
Geodetic pressure
g
UU
g
pp
zzH
⋅
−
+
⋅
−
+ − =
2
2
1
2
212
12
ρ






−
⋅
+








+
⋅
+
−






+
⋅
+








+
⋅
+ =
2
1
1
1
1
2
2
2
2
2
2
'
'
'
'
2
'
'
'
'
loss, friction,1 M
M
loss, friction, 2 M
M
H
g
U
z
g
p
z
H
g
U
z
g
p
zH
ρ
ρ
g
p
Hz
g
Vpp
NPSH
vapour
loss, friction, geo
barstat,in
A
⋅
− − +
⋅
⋅ ⋅ + +
=
ρρ
ρ
2
1
5.0
where H
loss,friction,1
and H
loss,friction,2
are the pipe friction loss-
es between pressure outlet and pump flanges.
The size of the friction loss depends on the flow velocity,
the pipe diameter, the distance from the pump flange to
the pressure outlet and the pipe’s surface roughness. Cal-
culation of pipe friction loss is described in section 5.3.1.
If the pipe friction loss between the pressure outlets and
the flanges is smaller than 0.5% of the pump head, it is
normally not necesarry to take this into consideration in
the calculations. See ISO 9906 section 8.2.4 for further
explanation.
6. Pump tests