Rosemount 5401, Reference Manual

Page: 36 / 180

Reference Manual
00809-0100-4026, Rev FA
July 2009
Rosemount 5400 Series
3-12
Vessel Characteristics
Heating coils, agitators and other objects in the tank may lead to disturbing
echoes and noise in the measurement signal. Vertical structures cause
minimal effect since the radar signal is scattered rather than directed back to
the antenna.
The shape of the tank bottom affects the measurement signal when the
product surface is close to the tank bottom. The Rosemount 5400 Series has
built-in functions which optimize measurement performance for various
bottom shapes (see “Tank Type and Tank Bottom Type” on page 5-4).
Disturbing Objects
The Rosemount 5400 Series transmitter should be mounted so that objects
such as heating coils, ladders, etc. are not in the radar signal path. These
objects may cause false echoes resulting in reduced measurement
performance. However, the transmitter has built-in functions designed to
reduce the influence from disturbing objects where such objects cannot be
totally avoided.
The Rosemount 5402 has a more narrow radar beam that is particularly
suitable in installations with tall or narrow nozzles, or nozzles close to the tank
wall. It may also be used to avoid disturbing objects in the tank.
Valves
The 5400 Series transmitter can be isolated from the process by using a
valve:
• Use a full-port ball valve
• The 5402 is required, and the Process Seal Antenna is the preferred
choice, since it does not require a spool piece. The cone antenna can
also be used
• Ensure there is no edge between the ball valve and the nozzle/pipe,
the inside should be smooth
Valves can be combined with pipes.