Intra Automation digiflow 515, Installation And Operating Manual

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Gas- and Steam Flowcomputer DigiFlow 515 Operating Manual
18
6.3.1 Programming The Flow Computer
So that the flow calculating machine can determine the exact flow according to equations 11 to 18, a number
of parameters have to be entered:
k
F
k-Factor (Flow Meters with Frequency Output)
S
M
Span (for Analog Outputs)
υυυυ
b
Base specific weight at which the span is deter-
mined.
The calculator will be measure the flow input A (normalized between 0 and 1), the temperature and the pres-
sure to calculate the specific weight, and enthalpy.
Example No. 7:
A VORTEX (k-Factor 68.32 Pulses/ft
3
) is used at saturized steam. The flow output shall be in lbs/hour.
What are the parameters to be programmed?
The calculator should be programmed for steam measurement at a frequency meter. Cause steam is satu-
rated, it is only necessary to use either the pressure input or the temperature input. Becaus of cost the tem-
perature sensor is used. Then the following parameters are to be entered.
Units: US
k-Factor: 68.32
Time Base: hours
Example No. 8:
A differential pressure transmitter across an orifice plate outputs 20mA at a flow of 10,000kg/h. Design pres-
sure is 1,300kPa
abs
and a specific weight of 216.5dm
3
/kg. The flowrate is required in kg/h and the caloric
value in MJ/h. What are the parameters to be programmed?
From the steam table we read a temperature of 350°C at 1,300kPa
abs
and a specific weight of 216.5dm
3
/kg.
Steam is in superheated state. Following parameters are to be entered for steam flow measuring with analog
input and square root relationship.
Units: SI
Span: 10,000
Base Temperature: 350°C
Base Pressure: 1300kPa
Time Base: hours
Type of Steam: superheated