Endress+Hauser Liquiphant FTL51B Operating Instructions Manual page 16

Installation
16
The marking on the adapter points in the flow direction.
Use the marking to align the tuning fork in such a way that the flow is not significantly
obstructed. The marking can also be recognized when the device is installed, see the "Fork
position marking" section .
Incorrect alignment
The marking on the adapter does not point in the flow direction.
Screwing in the device
Turn by the hex bolt only.
15 to 30 Nm (11 to 22 lbf ft)
A0034852
Do not turn at the housing!
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Liquiphant FTL51B
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Endress+Hauser