Revision 2.0 FOUNDATION Fieldbus ST 700 Pressure Transmitter User's Guide Page 43
3.7 Flow Transducer block
The Flow Transducer block (FTB) measures the flow rate of the fluid in the process. The
block supports both volumetric and mass flow. The block is supported only by the
Differential Pressure (DP) transmitter.
Figure 5: Flow Transducer Block
ATTENTION
If XD (Transducer) primary value type is not Differential Pressure, the block
raises a block configuration error and must not be used. Absolute and Gauge
Pressure units are not supported by the block.
Execution
The flow transducer block calculates the flow rate based on the rated flow input provided,
with the specified standard FF units. The rated flow refers to the fluid flow rate at the rated
pressure, which is the URV of the transmitter. The output of the flow is channelized
through the AI block so that the other function blocks like integrator block can use it to
totalize the flow.
The equation used for Flow transducer block is:
Where,
• F = Flow F in specified units.
• F
URV
= Rated flow or design flow at Rated Pressure (URV) in same units.
• ∆P = Orifice delta P. This is available from Pressure Basic Block PV.
• ∆P
URV
= Design orifice delta P. This is the URV ∆P of the transmitter.
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