Vega VEGAPULS 62 Operating Instructions Manual page 21

4 Mounting
Measurement in the by-
pass
20
The measurement through a ball valve with complete run is
l
possible
Constructional requirements on the surge pipe:
Material metal, smoother inner tube
l
Preferably pultruded or straight beaded stainless steel tube
l
Welded joint should be straight and lie in one axis with the holes
l
Flanges are welded to the tube according to the orientation of the
l
polarisation level
In case of a extension with a welding neck flange or pipe collar as
l
well as when a ball valve is used, the inner surfaces should be
aligned and accurately joined together
Gap size with junctions ≤ 0.1 mm
l
Do not weld through the pipe wall. The surge pipe must remain
l
smooth inside. Roughness and beads on the inside caused by
unintentional penetration should be removed since they cause
strong false echoes and encourage buildup
Surge pipes must extend all the way down to the requested min.
l
level, as measurement is only possible within the tube.
Diameter of holes ≤ 5 mm, any number OK, on one side or
l
completely through
The antenna diameter of the sensor should correspond to the
l
inner diameter of the tube
Diameter should be constant over the complete length
l
An alternative to measurement in a surge pipe is measurement in a
bypass tube outside of the vessel.
VEGAPULS 62 • 4 ... 20 mA/HART two-wire