KROHNE ALTOSONIC V12 EN - Manual (Page 12)

2
DEVICE DESCRIPTION
12
ALTOSONIC V12
www.krohne.com 04/2013 - 4002643502 - MA ALTOSONIC V12 R02 en
A series of acoustic transducer are installed on the inside of the meter body. Each pair of
ultrasonic transducers forms an acoustic measurement path. The acoustic measurement path
consists of one (direct) chord or two (reflective) chords.
The chords in the horizontal plane are used for flow measurement, the chords in the vertical
plane are used for diagnostics only. The reflective chords that are offset from the meter’s centre
line use acoustic mirrors to reflect the ultrasonic signal. The reflective chords that are in the
centre line of the meter reflect directly on the pipe wall. Direct chords do not reflect and
therefore do not require acoustic mirrors.
The transducers are electrically connected to the electronic unit on top of the meter by means of
coaxial cables. The cabling is protected against mechanical damage and moisture by means of
covers. The coaxial cables enter the electronics enclosure through its “foot” (or support). In this
foot an Ex d approved cable feed through is installed that closes this entry to the electronics
enclosure.
On the other side the coax cables are connected to the transducers, this connection is also done
by an Ex d approved connector
2.2.1 Transducers
Acoustic signals are transmitted and received by means of ultrasonic transducers. The active
part of an ultrasonic transducer is a small disk of piëzo electric ceramic in the front of the
transducer. It is packaged (sealed) in a construction of metal parts and high grade epoxy or
inside a titanium housing. The front side of the transducer is exposed to the gas to be measured,
this results in the best efficiency for transmitting and receiving ultrasound.
Figure 2-2: Location of sensors and electronic unit
Overview installation of transducer
Figure 2-3: Sensor assembly
1 Double O-ring
2 Slot in the socket
3 Ex-d socket
4 Ex-d plug
5 Alignment pin
6 Cap
7 Securing screw M2
8 Coaxial wire
9 Transducer nut