ABB C1300 User Manual Supplement page 7

...2.1.3 Mass Flow 1 and 2
Example B – calculating the mass flow of water from the volume flow.
At a temperature of 15.6°C (288.6K) and an absolute pressure of 1013.25 mbar, 1 liter of water has a mass of 1kg.
To calculate the mass flow of water from the volume flow the following settings are used:
PV1 – volume flow of water (liters/min)
PV2 – temperature of water (°C)
PV3 – pressure of water (mbar (abs))
PV4 – result of math block 1 (kg/min)
therefore the equation is:
The example below shows the construction of Math block 1 with the following selected:
• math block function –
• input A source –
Process Variable 1
• input t source –
Process Variable 2
• temperature units –
Deg C
• temperature reference (process conditions using maximum flow rate) –
input P source –
• Process Variable 3
• pressure reference (process conditions using maximum flow rate) –
• scaling constant –
1.000
Note.
• Ensure that the temperature input/temperature reference have the same units and the pressure input/pressure reference
have the same absolute units.
• The basic mass flow equation must use absolute temperatures (K or °R). The C1300 converts automatically from °C or °F
to absolute.
• If temperature or pressure correction is not required, set the temperature or pressure inputs to
Mass 1
2 MATH CONFIGURATION...
15.6
1013
None
– see Section 2.2.3.
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