Siemens SITRANS L, Руководство по эксплуатации, Страница: 29 / 269

Installing/mounting
4.3 Proper mounting
SITRANS LR250 with FOUNDATION FIELDBUS
Operating Instructions, 09/2021, A5E32221411-AH
29
4.3.3 Orientation in a vessel with obstructions
Polarization reference point
For best results on a vessel with obstructions, or a stillpipe with openings, orient the front or
back of the device toward the obstructions. For an illustration, see Device orientation
(Page 30).
① Polarization axis
② Polarization reference point
③ Display
4.3.4 Mounting on a Stillpipe or Bypass Pipe
A stillpipe or bypass pipe is used for products with a low dK, or when vortex or extremely
turbulent conditions exist. It can also be used to provide optimum signal conditions on
foaming materials. See Dielectric constant of material measured in Performance (Page 178)
for more information.
•
The pipe diameter must be matched with the antenna size. Use the largest antenna size
that will fit the stillpipe/bypass pipe
1)
. See Threaded Horn dimensions (Page 191), Raised-
Face Flange per EN 1092-1 (Page 225), Flanged encapsulated dimensions (Page 200)or
Hygienic encapsulated dimensions (Page 205).
• One continuous length of metallic pipe is preferred, without joints.
• Any false reflections created by joints/welds/imperfections will lead to inaccuracies of the
measurement.
• Joints (if unavoidable) must be machined to ± 0.25 mm (± 0.010") and must have weld ed
connecting sleeve on the outside.
• If using any hygienic process connections in conjunction with a stillpipe/bypass, please
ensure that the antenna/lens are cleanable in accordance with the applicable approval.
1)
Mounting in a pipe greater than 100 mm (4") can cause large errors, and therefore is not
recommended.
Suitable pipe diameters: Horn antenna 40 to 100 mm (1.5 to 4")
PVDF antenna 50 mm (2") only
Flanged encapsulated antenna 50 to 100 mm (2 to 4")