Honeywell HERMetic UTImeter Gtex Chem, Operation And Service Manual

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7.2 ULTRA sensing probe
7.2.1 Introduction
The ULTRA sensing probe consists of a stainless steel
tube terminated by a high-tech plastic head which cannot
be removed from the tube. The sensing probe includes an
ultrasonic liquid level sensor, a temperature sensor and a
conductivity electrode. The sensitivity for ullage and interface
measurement is not adjustable. The temperature measurement
is calibrated at the factory and does not require subsequent
adjustment.
7.2.2 Ullage detection
The ullage detector consists of two piezoceramic plates and
electronic circuits. When the sensor head is immersed in a
non-conductive liquid (oil or petroleum), the emitted ultrasonic
signal is detected by the receiver, coded and sent to the
instrument unit which activates the buzzer with the continuous
beep.
1
6
0
1
2
3
4
5
0
1
1
2
1
Reaction point
4 mm
Ultrasonic level sensor
Air
Liquid
Figure 7-3
The reaction point is located 4 mm (5/32”) from the sensor bottom and identical with the zero-point of the tape graduation.