Emerson Rosemount 3308 Series Reference Manual page 28

Installation
February 2020
3.3.4 Installation in still pipe/chamber
General chamber considerations
Dimensioning the chamber/pipe correctly and selecting the appropriate probe is key to
the success in these applications. When selecting a smaller chamber/pipe diameter, such
as 2-in., a flexible probe is not suitable due to the chance of it coming into contact with the
walls. Also, relatively large side inlets may interfere with the signal.
When gas lift and/or turbulence may occur (e.g. boiling hydrocarbons), a 3- or 4-in.
chamber/pipe diameter is recommended for maximum measurement reliability. This is
especially true in high pressure and high temperature installations.
Table 3-3: Recommended and Minimum Chamber/Still Pipe Diameters for Different
Probes
Probe type
Rigid single/segmented rigid
single
Flexible single
Flexible twin
Coaxial
(1) The center rod must be placed more than 0.6 in. (15 mm) away from the pipe wall.
Note
Metal pipes are preferred, especially in applications with low dielectric constant, to avoid
disturbances from objects near the pipe.
Related information
Dimensional drawings
Rosemount chamber
A Rosemount chamber allows external mounting of process level instrumentation. It
supports a variety of process connections, and optional drain and vent connections. The
standard Rosemount chambers are designed according to ASME B31.3. Rosemount
chambers compliant with the Pressure Equipment Directive (PED) are available. Customer
specific engineered solutions for Rosemount chambers are available upon request. Use
option code XC to order together with the Rosemount 3308A Series Transmitters.
28
Recommended diameter
3 or 4 in. (75 or 100 mm)
4 in. (100 mm)
(1)
4 in. (100 mm)
3 or 4 in. (75 or 100 mm)
Reference Manual
00809-0100-4308
Minimum diameter
2 in. (50 mm)
Consult your local Emerson
representative
Consult your local Emerson
representative
1.5 in. (37.5 mm)
Rosemount 3308 Series