Intra Automation digiflow 515, Installation And Operating Manual

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Gas- and Steam Flowcomputer DigiFlow 515 Operating Manual
13
Example No. 2:
A flowmeter produced a mass flow of 1,000kg/h. Temperature of 30°C, pressure of 220kPa and specific
Gravity of 1.52.
Using equation
[
2
]
gets:
ρ =
⋅ ⋅
⋅ +
3 4834 152 220
1 30 27315
. .
( . )
ρ =
3 84
3
.
kg
m
(assuming: z
b
= 1)
Therefore from equation
[
9
]
the span will be: S
Vb
= 260 m
3
/h.
If the span is programmed as mass SM = 1,000kg/h at reference conditions of 30°C and 220kPa, then the
display of mass flow and volume flow referenced to these conditions.
Example No. 3:
Shall the volume flow from above example calculated into „standard“ conditions, then the setable values are
15°C and 101.325kPa
abs
.
Then the span will be: S
Vb
= 537.2 sm
3
/h.
6.1.2 Application for Ideals Gases
If the influence of the compressibility on gases can be ignored, then the factors Zb and Zf in the equations 1
to 8 will be set to "1".
The computings become substantially simpler with these approximations. These approximations are applica-
ble for:
•
Gases of 1. Gas range (also at higher pressures)
•
Gases of 2. Gas range up to 20bar
Example No. 4:
A VORTEX is used to measure oxygen in a pipe at 25°C and 200kPa
abs
. The VORTEX produces 9,500
Pulses/m
3
and the flowrange is 100 to 1,000m
3
/h.
Determine the flow parameters which need to be programed into the instrument for it to display the flowrate
and total flow as both mass and corrected volume to standard conditions.
From the table, the molecular weight of oxygen is: 31.9988mol/g
From equation (1):
d
g
mol
g
mol
= =
31 9988
28 9625
1105
.
.
.
According to ISO 5024, Standard Conditions are 15°C at 101.325kPa. Hence the following values are pro-
grammed into the instument: