Azbil JTD720A, User Manual, Page: 11 / 76

Azbil Corporation Functions, Configurations, and Structures of model JTD720A and communicator
Model JTD720A - Smart Multivariable Transmitter 1-1
Chapter 1 : Functions, Configurations,
and Structures of model
JTD720A and communicator
1-1 : Function and Configuration
The differential pressure transmitter with temperature/pressure compensation, model
JTD 720A, is designed for gas flow measurement.
Temperature sensor
(RTD)
Air
Mass flow
(output after temperature and
pressure compensation)
JTD720A
• Differential pressure / pressure
measurement
• Saturated steam compensation
Figure 1-1 Instrumentation example of the transmitter with temperature/pressure
compensation
This transmitter simultaneously measures the process differential pressure, static
pressure, and temperature, and compensates for changes in density due to static
pressure fluctuation and temperature fluctuation, as shown in the block diagram in
figure 1-1. After compensation, it transmits an output proportional to the mass flow
(the volumetric flow in Nm3 / unit of time under standard conditions).
In addition, various settings of the transmitter (differential pressure range, design
pressure, design temperature, square root output, damping time constant, etc.) can be
specified using the communicator.
Mass flow
(output after temperature and
pressure compensation)
JTD720A
• Differential pressure / pressure measurement
• Saturated steam compensation
Saturated steam
Figure 1-2 Instrumentation example of the transmitter with temperature/pressure
compensation (saturated steam compensation)
Differential pressure DP
Static pressure PP
Static pressure
Design temperature
Temperature Design pressure
Temperature PT
DP–LRV
For linear
For square root extraction
Damping output
URV–LRV
× ×
√
Figure 1-3 Block diagram of calculation by transmitter with temperature/pressure compensation