Emerson Process Management 00809-0700-4530 Radar Detector User Manual


 
6
Reference Manual
00809-0700-4530, Rev AA
Section 2: Installation Considerations
September 2013
Installation considerations
2.2 Introduction
In addition to selecting the appropriate radar level transmitter, mechanical installation is one of
the most critical steps of the commissioning procedure. When done correctly, the subsequent
transmitter configuration will be considerably simplified. Because of the wide usage and
application in the power industry, this section provides a framework for chamber installations,
tank installations, and solids measurements.
2.3 Chamber installations
Chambers - also known as bridles, side-pipes, bypass pipes, and cages - are typically used
because:
External mounting with valves allows for servicing of the level device, even in
pressurized tanks that are in continuous operation for many years
They allow for radar measurement in tanks or regions with side-connections only, such
as boiler drum, condenser and feedwater tanks
They provide a calmer surface in case of turbulence, boiling, or other conditions that
upset the product
NOTE:
For chamber installations, use metallic pipes exclusively.
However, chambers also have some disadvantages:
Inlet pipes may clog and generate a discrepancy between the level inside the chamber
and the actual level in the tank
The effective measuring range is limited to the region between the upper and lower
inlet pipes
Different process conditions (temperature/pressure) in the chamber than in the tank
may generate discrepancy between the level inside the chamber and the actual level in
the tank
A pipe can increase the reliability and robustness of the level measurement, especially for
non-contacting radar. It should be noted that the coaxial probe of a Guided Wave Radar (GWR)
is essentially a probe within a small stilling well. It should be considered as an alternative to
stilling wells for clean fluid applications.
Pipes completely isolate the transmitter from disturbances, such as other pipes, agitation, fluid
flow, foam, and other objects. The pipes can be located anywhere in the vessel that allows
access. For GWR, the microwave signals are guided by the probe, making it resistant to
disturbing objects.
Bypass chambers may be located on a small portion of a tank or column and allow access to the
measurement instrument.
Bypass chambers often include valves to allow instrumentation calibration verification or
removal for service.
Bypass chambers and stilling wells are not without limitations. Generally, pipes should be used
with cleaner fluids that are less likely to leave deposits and that are not viscous or adhesive.