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4.2
Installation and Care of Transmitter
The transmitter should be installed within the pipe work system such that the metering pipe is
always filled with liquid, because the transmitter can register some flow, even when the meter
is empty.
As the transmitter will measure any air in the liq-
uid as a part of the total volume, the volume of
the air must be reduced to an absolute minimum.
To help achieve this, the transmitter should be
located in the pipe work system at the point of
maximum pressure. Here the volume of the air
will be at a minimum and thus the influence of air
on the measurement will also be at a minimum. It
is therefore recommended that control valves, or
other restrictions that might create a pressure
drop, are mounted after the Flow Transmitter.
Even when there is no air in the liquid it is impor-
tant to ensure that the pressure is sufficiently high,
otherwise cavitation may occur in the transmitter.
Not only will this influence the accuracy, but it is
also destructive to the Teflon lining.
18/55
Ensure that the valve is always mounted
after the Flow Transmitter (downstream).
Flow Transmitter, PD 340
The graphs to the left show the
required minimum gauge pres-
sure (measured in the pipeline
after the Flow Transmitter) as a
function of flow at different op-
erational temperatures. Always
ensure that the gauge pressure
is well above the curve defined
by the relevant operational tem-
perature. Please observe that
the dotted parts of curves fall
outside the allowable opera-
tional specifications and are only
shown as extrapolations from
permitted values. Using the
transmitter under these condi-
tions may cause damage, which
will not be covered under the
product guarantee.
551 198 01
Manual
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