Siemens Sitrans LR250, Руководство по эксплуатации, Страница: 34 / 306

Installing/mounting
4.3 Proper mounting
SITRANS LR250 (PROFIBUS PA)
32
Operating Instructions, 08/2014, A5E32221386-AC
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 179) 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 187), Raised-Face
Flange per EN 1092-1 (Page 221), Flanged encapsulated dimensions or Hygienic
encapsulated dimensions.
● 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 welded
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")
Hygienic encapsulated antenna 50 to 100 mm (2 to 4")
Not recommended: > 100 mm (4")
Bypass vent: Required at the upper end of the bypass
1)
1)
To equalize pressure and keep the liquid level in the bypass constant with the liquid level in the
vessel.