Tecfluid LU Series - Manual (Page 4)

4
1 INTRODUCTION
The series LU transmitters are electronic equipment based on the transmission of
ultrasonic waves to measure the distance to a liquid or solid in a vessel.
The micro processed electronic circuit offers the following features:
 Emission and reception circuits for the ultrasonic signals, and microprocessor
treatment.
 Alarm outputs with programmable hysteresis level.
 Programmable current output proportional to the distance or level.
 HART protocol compatibility (models LU9XH and LU921H).
2 INSTALLATION
2.1 General
To make the instrument to work in the best conditions, it is important that the bottom face
of the sensor be installed parallel to the surface of the product to be measured. In the
case of liquids, the face of the transducer should be horizontal.
It is important to avoid installing the instrument at the center of the vessel. In some cases
may appear unwanted echoes that affect the measurement. The installation at the center
is only advantageous in vessels with tapered bottom, since distances can be measured to
the
bottom.
The transmitters LU should be installed at a minimum distance of the walls of the vessel
of about 200 mm, so that they could not give unwanted reflections.
The socket where the instrument is installed should be such that the bottom of the
instrument exceeds at least 10 mm below it, as shown in the drawing.
Screw the instrument in the socket with an appropriate key, always by the flats for this
purpose. The maximum torque is 25 Nm.
Never use the electronics housing for threading the device to the vessel.
2.2 Measuring range
The minimum distance that the instrument can measure is called dead zone. If the
product gets closer than that distance, the display indicates dashes instead of the