PD39X_Differential_pressure_transmitter_Riels0 pages

PD39X

DIFFERENTIAL
PRESSURE
TRANSMITTER

PRESSURE
CONTROLS

Differential pressure transmitter based on two absolute sensors
In applications where the differential pressure is more than 5% of the maximum standard pressure range, differential pressure measurement with two absolute pressure sensors
offers major advantages over conventional methods of differential pressure measurement
(such as the Series PD-10).

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The Series PD-39 X does not measure the differential pressure directly - instead, it uses two
absolute pressure sensors to take the measurement indirectly. As well as reducing costs, this
differential pressure transmitter is also more robust in relation to unbalanced (one-sided)
overloading. The differential pressure range should be at least 5% of the standard pressure
range. Each pressure side has two pressure connections, so the PD-39 X is easy to use in
pressure lines.
So that the differential pressure can also be measured exactly if the standard pressure range/
differential pressure ratio is high, this series also features the tried-and-tested microprocessorbased technology that is used in Series 30 X.
All reproducible pressure sensor errors (i.e. nonlinearities and temperature dependencies)
are entirely eliminated thanks to mathematical error compensation. The sensor signals are
measured with a 16-bit A/D converter, so the individual standard pressure ranges can be
measured to an accuracy of 0,05%FS throughout the entire pressure and temperature range.

Low pressure version

Digital Interface
The transmitters have a bus-compatible two-wire RS485 half-duplex interface which is modelled on the ”MODBUS RTU”. RIELS offers interface converters to RS232 or USB for use
here. The READ30/PROG30 program and the protocol are freely available.
The interface offers these capabilities:
– Readout of pressure and temperature values for both sensors.
This allows readout of the differential pressure as well as the two standard pressure ranges.
– Calibration of zero points and amplification.
– Scaling of the analog output to different pressure ranges or units.
– Configuration settings such as measurement rate, low-pass (LP) filter, bus address, etc.
– Readout of information such as serial number, compensated pressure and temperature
ranges, etc.
Medium pressure version

Analog Output:
The analog output is freely scalable via the interface. For flow measurements, the root of the
differential pressure can also be outputted. The calculated value can be outputted via an
analog interface (0…10 V or 4…20 mA).

Riels Instruments Srl

+39 049 8961771

+39 049 717368 www.riels.it info@riels.it