Answer / sam

You first need to have a flow element like a orifice plate
installed in order to get a differential pressure across the
orifice. You then need to measure this differential pressure
with the differential pressure transmitter or a u-tube or
two pressure gauges at various flow rates. If this is not
possible the orifice plate manufacturer will give you the
minimum and max diff pressure across the orifice plate for
various flow rates and liquids. You should already have the
pipe size, the orifice plate details and the liquid you will
use in this application.
Once you have this minimum and maximum diff pressures for
the minimum and max flow rates you can see on the
transmitter range if it will be big enough to measure these
diff pressures. The signal can be send from the transmitter
directly to the DCS and the squire roof extraction can be
done there or you can do the SQ extraction on the
transmitter itself by modifying it's configuration to
measure flow.

Answer / kannan.r

range of dp tx and range of output is entirely different.
first of all to measure flow, we need primary elements like
ventury tube, flow nozzle, annubar which will restrict the
flow and so that dp will create.
from the manufacture of the primary element itself the
constant value should be noted. then only we can calculate
the flow using dp tx.

Answer / umashankar soni

DP transmitter are used for flow measurement in combination
with flow obstructing devices such as
venturi,orifice,nozzle or aerofoil,which have tested
characteristics i.e. pressure drop across them for a
perticular flow.

This characteristic is then used with DP transmitter to
measure flow.

Answer / sarma

simply measure dp at max flow. caliberate dptx to that
value. select output sqrt in dptx. if its out of range of
dptx. adjust orifice and try.

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