Answer / zahid ibrar

DEFFERENTIAL PRESSURE TRANSMITTER:
BY THE NAME IT IS KNOWN THAT THIS TRANSMITTER GIVE THE
OUTPOUT BY SENSING THE PRESSURE DIFFERENCE. THERE ARE TWO
SIDE OF THIS TRANSMITTER AND HAVING THE DIAPHRAM FILLED
WITH LIQUID, AND AFTER THAT LIQUIDE THERE IS VARIABLE
RESISTANCE OR CAPACETANCE CIRCUIT. WHEN PRESSURE EXURT ON
THE DIAPHRAM IT TRANSFER PRESSURE TO THE CAPACITANCE OR
RESISTANCE CIRCUIT THRUGH FILLED LIQUIDE, BYWHICH
RESISTANCE OR CAOACTENCE VARRIY AND GIVE TO TRANSMITTER
ELECTRONIC CIRCUIT THAT CONVIRT AND AMPLYFY THE SIGNAL ANTO
MA. AND TRANSMIT IT.

Answer / raffi

DPT - Differential Pressure Transmitter

For Ex: Orifice plate is the Flow Element
The H.P side of the process line is connected to the H.P
side of DPT and L.P side of the Trasnmitter is connected to
the L.P side of The DPT. When the Pressure enters the DPT
it Senses the Differntial pressure(H.P-L.P) and converts it
into 4-20mA DC and transmit the signal to the PLC

Answer / eswar

the differential presser acting on a sensing diaphragm
produces a force therefore we get diaphragm
deformation(small 10^-5m).This displacements we can measure
through variable capacitance or variable reluctance
,resistive strain gauge sensors.This sensor output is
connected to a bridge which gives the output voltage.Then
instrumentation amplifier converts the voltage to current
which we can transmit to the control room.

Answer / visakh

D ifferential pressure transmitter has two ports,
ie high pressure port and low pressure port , these two
ports connects to the pipeline or tank..etc by a metal
tube.the difference in pressure from the two port strikes
on the diaghpraghm inside the transmitter,then the
dighpragm get a little movement , the transducer in the
transmitter converts the mechanical movemeet to electrical
signal, ie 4-20ma

Answer / selvakumar

DPT is give the output of difference of the HP and LP.
Process line Upstream side is connected to the HP side(P2)
of the transmitter. Downstream side is connected to the LP
side(P1) of the transmitter. Output will come like this
(P2-P1). Q = k (Root of Delta P). Delta P = P2-P1.k =
constant.

Onemore type is there. Diapharm type it is also working as
well as DPT. But Silicon oil is filledup the inside of the
cabbilary. This oil will push the diapharm of the
transmitter, then resistance value will change,
corresponding to the input pressure.Corresponding the mA
will converted by transmitter.

Answer / ram

Question is very simple but my all above friends had make it
more complicated for a normal person.

Funda of DPT is only to measure the pressure of one area
with respect the pressure of the other area. and gives the
output readings accordingly. Different working mechanism is
used by different manufacturer. But the basic of all remains
same.

When doing a liquid seal on a differential flow transmitter , most of the time the sealing liquid will be heavier then the process fluid. For wich application will the sealing liquid be lighter than the process fluid if transmitter is mounted below the process line.

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