Measuring Ranges
Superheated Steam
and Gas
Volumetric/Mass Flow (V/m)
m [kg/h] = V [m
3
/h] • ρ [kg/m
3
]
V [m
3
/h] =
m [kg
⁄
h]
ρ [kg
⁄
m
3
]
Example for Superheated Steam
To determine:
Nominal diameter to measure super-
heated steam at 250 °C and 15 bar abs.
at a flowrate of 10 t/h.
Calculation:
a) Convert t/h
⇒
m
3
/h using the density
of steam (6.58 kg/m
3
) from the table.
V [m
3
/h] =
m
ρ
=
10000
kg
⁄
h
6.58 kg
⁄
m
3
= 1520 m
3
/h
b) Select the nominal diameter in the
steam/gas measuring range diagram
below for V = 1520 m
3
/h
⇒
DN 100.
For
ρ
= 6.58 kg/m
3
the initial value for
the measuring range is 90 m
3
/h as the
initial value is dependent on the density.
This gives a measuring range of
90...2430 m
3
/h or 590...15990 kg/h.
Corrected/Operating Volume (V
C
/V
O
)
V
O
[m
3
/h] =
V
C
[Nm
3
⁄
h] •
T
O
[K]
273.15 K • P
O
[bar abs.]
V
C
[Nm
3
/h] =
V
O
[m
3
⁄
h] •
273.15
K • P
O
[bar abs.]
T
O
[K]
• 1.013 bar
Corrected/Operating Density (
ρ
C
/
ρ
O
)
ρ
O
[kg/m
3
]=
ρ
C
[kg
⁄
Nm
3
] • P
O
[bar
abs.]
• 273.15
K
T
O
[K]
ρ
C
[kg/Nm
3
] =
ρ
O
[kg
⁄
m
3
] • T
O
[K]
P
O
[bar abs.] •
273.15 K
T
O
= operating temperature
P
O
= operating pressure
•
•
•
•
Density is an important parameter for many calculations, e.g. in corrected volumes.
The density of steam as a function of temperature and pressure can be determined
from the following table.
P Density of steam [kg/m
3
]
[bar
abs]
150
°C
200
°C
250
°C
300
°C
350
°C
400
°C
0.5
1.0
1.5
0.26
0.52
0.78
0.23
0.46
0.70
0.21
0.42
0.62
0.20
0.38
0.57
0.17
0.35
0.52
0.16
0.32
0.49
2.0
2.5
3.0
1.04
1.31
1.58
0.93
1.16
1.39
0.83
1.04
1.25
0.76
0.95
1.14
0.69
0.87
1.05
0.65
0.81
0.97
3.5
4.0
5.0
1.85
2.12
1.63
1.87
2.35
1.46
1.68
2.11
1.33
1.52
1.91
1.22
1.40
1.75
1.13
1.29
1.62
6.0
7.0
8.0
2.84
3.33
3.83
2.54
2,97
3.41
2.30
2.69
3.08
2.11
2.46
2.82
1.95
2.27
2.60
10.0
12.0
15.0
4.86
5.91
7.55
4.30
5.20
6.58
3.88
4.67
5.89
3.54
4.26
5.36
3.26
3.92
4.93
20.0
25.0
30.0
8.98
11.49
14.17
7.79
10.11
12.32
7.21
9.11
11.05
6.62
8.33
10.07
35.0
40.0
17.03 14.61
16.99
13.02
15.05
11.84
13.63
50.0
64.0
80.0
22.07
30.08
41.22
19.26
25.53
33.93
17.30
22.66
29.15
100.0
120.0
140.0
44.60
58.40
75.70
37.86
47.44
58.04
160.0
180.0
200.0
102.42 70.08
83.96
100.53
220.0
240.0
250.0
121.20
148.39
166.28
ti031e52
V in m
3
/h
Density dependent
start of measurement
1% o.f.s.
Note: This diagram serves as a guideline for a quick estimation of Prowirl measuring
ranges. Your E+H sales organisation will be pleased to help you select and dimen-
sion a flowmeter for your application.
The below formulaes show the convertions from operating- to corrected volume and
density, and vice-versa.
11
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