Operation & Installation Manual V12-V6 2010-05-31.doc
31/05/2010
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Figure 2-6: Location of sensors and electronics of an ALTOSONIC V12
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 or a case that is welded around part of the meter body.
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 Figure 2-11.
2.3 Detailed description
2.3.1. Ultrasonic transducer
Acoustic signals are transmitted and acoustic signals are 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. The front side of the transducer is exposed to the fluid to be
measured, this results in the best efficiency for transmitting and receiving ultrasound.
The electrical signals are connected to the piëzo electric disk by means of a glass sealed
feed through. This provides for an effective sealing of gas at high pressure.
The transducers have an Ex-d connector (socket, ref 1. Figure 2-7) that connects to a to an
Ex d connector (plug, ref 2.) which terminates a coaxial wire (ref 3.)
A pin (ref 4.) on the connector engages with a slot in the socket (ref 5.), this makes sure the
transducer is connected with the correct polarity.
The cap (ref 6.), screwed onto the socket, fastens the connector, a small screw (M2) (ref 7.)
secures this cap. The transducers are fastened in the meter body using a nut with a hole in
the centre (ref 8.)
A double O-ring (ref. 9) seals the pressure inside the piping effectively from the outside
world.
