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| Calculation
of Diameter |
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Calculation of liquid
* Volumetric flowrate of liquid to be measured Qt(l/h)
Put density and maximum flowrate of measured liquid into Formula
1, and calculate the flowrate of water！standard medium; then,
find out the corresponding diameter and float number from
flowrate table and put the flowrate of water provided by standard
float No. into Formula 1 again, accordingly, make out the
flowrate of measured liquid; finally, adjust the flowrate
into an integer so that to get the scale range of liquid to
be measured.
* Mass flowrate
of liquid to be measured Qm(kg/h)
Calculation formula of scale range is as follow
while calculation method is as above:
| Thereinto: |
Qt ----- Max volumetric
flowrate of liquid to be measured(
l/h) |
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Qm --- Max mass flowrate of
liquid to be measaured(kg/h) |
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Qs -----flowrate of standard
medium water(l/h) |
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ρf-------Density of float(kg/m3) |
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ρt-------Density of liquid to
be measured(kg/m3) |
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ρs-------Density of water(kg/m3) |
*
Example
Some liquid to be measured, its operating
density is 850 kg/m3 and max. flowrate
is 2400 1/h, please calculate its
diameter, float No. and scale range.
Solution: density of float ρf = 7800
kg/m3, density of water ρs = 1000
kg/m3
Put ρt = 850 (kg/m3) and Qt = 2400
(1/h) into Formula 1 to get Qs = 2188.86
1/h
Then, look up the flowrate table and
find out: DN25, float No. F26.3, Qs
=2500
Put Qs into Formula 1 again to get
Qt = 2741.23,
Then adjust it into an integer, get
the scale range of this fluid: 270
- 2700 1/h.
| Calculation
of gas |
|
| Gas
is easily affected by temperature
and pressure and quite different
from liquid. Therefore, at the
time of calculating flowrate,
we do not only consider the
density factor, but also take
account of the influences from
temperature and pressure, so
it is extremely important to
provide correct temperature
and pressure of gas to be measured
under operating condition. |
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| * Standard flowrate
of gas to be measured QN(Nm3/h) |
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| * Operating flowrate
of gas to be measured Qt(m3/h) |
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| * Mass flowrate
of gas to be measured Qm(kg/h) |
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Thereinto:
QN ----- Max. volumetric flowrate
of gas under standard condition(Nm3/h)
Qt------ Max. volumetric flowrate
of gas under operating condition
(m3/h)
Qm-----Max. mass flowrate of
gas in operating condition (kg/h)
Qs ----- Flowrate of standard
medium air(m3/h)
ρs ------Density of air under
standard condition (kg/m3)
ρst ----- Density of gas under
standard condition (kg/m3)
ρt ------ Density of gas under
operating condition (kg/m3)
Ps--------Absolute pressure
of air under standard condition
(0.1MPa)
Pt--------Absolute pressure
of gas under operating condition
(MPa)
Ts------- Absolute Temp. of
air under standard condition
(293.15K)
Tt--------Absolute Temp. of
gas under operating condition
(K)
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* Example
Some gas to be measured, oxygen,
its average molecular weight:
32; process pressure: 0.4 MPa(gauge
pressure), process temperature:
25≧, Max. flowrate: 35 Nm3/h,
please calculate its diameter,
float No. and scale range.
Solution: ρs = 1.20kg/m3, Ps
= 0.1MPa, Ts = 293.15K,
ρst = 1.331kg/m3, Pt =
0.5MPa, Tt = 298.15K, QN = 35Nm3/h
Put the acquired data into Formula
3 to get Qs = 16.60 m3/h
Look up flowrate table, find
out: DN 15, Float No: F16.8,
Qs = 18
Put Qs into Formula 3 again,
make out QN = 37.96
Then adjust it into an integer
and get scale range of measured
fluid: 3.8 - 38 Nm3/h
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