Pressure loss
D
p
at normal conditions
for air (1.013 bar/0
°
C/
r
n = 1.29 kg/m
3
)
(14.69psi / 32
°
F /
r
n = 0.0805 lbs /ft
3)
See Diagram I
for water (20
°
C/
r
n = 998.2 kg/m
3
)
(68
°
F /
r
n = 62.31 lbs /ft
3)
See Diagram II
at operating conditions
D
p
pressure loss in Pa
for gases and liquids
D
p = C * qv2 *
ρ
x
C constant
(see
Table)
q
v
flow rate in m
3
/hr
for standard vapour
D
p = C * q
m
2
q
m
flow rate in kg/hr
r
x
r
x
operating density in kg/ m
3
Diagram I
Pressure loss
D
p for air 1.013 bar (14.69 psi)
/
0
°
C(32
°
F) /
r
n
=1.29 kg/m
3
(0.0805 lbs/ ft
3
)
D
p (psig)
D
p (mbar)
Diagram II
Pressure loss
D
p for water
20
°
C (
68
°
F
)/
r
n=998.2 kg/m
3
(
62.31
lbs/ft
3
/)
D
p (psig)
D
p (mbar)
7
5
3
2
7
5
3
2
7
5
3
2
10
1
A B C D
E
F
G
H
I
J
K
2 3 5 7 10
2 3 5 7 100
2 3 5 71000
2
0.1
3 5 7 10000
1
1.02
0.73
0.44
.29
.15
.10
0.073
0.044
0.029
0.015
0.010
0.0 073
0.0044
0.0029
0.0015
1.45
100
62 1
10
100
1000
10000
2 3 5 7
2 3 5 7
2 3 5 7
2 3 5 7
m /h
US GPM
3
7
5
3
2
7
5
3
2
7
5
3
2
100
10
A B C D E F G H I J K
2 3 5 7 1
2 3 5 7 10 2 3 5 7100
2 3 5 7 1000
0
10.15
7.25
4.35
2.90
1.45
1.02
0.73
0.44
0.29
0.15
0.10
0.07
0.044
0.029
0.015
14.50
1000
44 1
10
100
1000
2 3 5 7
2 3 5 7
2 3 5 7
2 3 5 7
m /h
US GPM
3
m3/hr
m3/hr
Table for diagrams I +II and Constant C
Curve
Meter size (DIN/ANSI)
Constant C
A
DN 10S , 3/8 ” S
13.7
B
DN 10 , 3/8 ”
3.42
C
DN 15 ,1/2 ”
1.75
D
DN 20 , 3/4 ”
0.45
E
DN 25 , 1 ”
1.50
*
10
-1
F
DN 40 , 1
1/2
”
3.30
* 10
-2
G
DN 50 , 2 ”
7.80
* 10
-3
H
DN 80 , 3”
1.90
* 10
-3
I
DN 100 , 4”
5.30
* 10
-4
J
DN 150 , 6”
1.60
* 10
-4
K
DN 200 , 8”
5.90
* 10
-5
58
