Emerson Rosemount 3308, Reference Manual

Page: 40 / 128

Reference Manual
00809-XXXX-4811, Rev AA
February 2012
Rosemount 3308
4-6
PRELIMINARY
Flange Connection on Nozzles
Figure 4-2. Mounting in nozzles
The transmitter can be mounted in nozzles by using an appropriate flange. It
is recommended that the nozzle size is within the dimensions given in
Table 4-1 . For small nozzles it may be necessary to increase the Upper Null
Zone (UNZ) in order to reduce the measuring range in the upper part of the
tank. By setting the UNZ equal to the nozzle height, the impact on the
measurement due to interfering echoes from the nozzle will be reduced to a
minimum. See also section
“Disturbances at the Top of the Tank“ on
page 7-10 . Amplitude Threshold adjustments may also be needed in this
case.
NOTE
Except for the Coaxial Probe the probe must not be in contact with the nozzle.
Table 4-1. Minimum nozzle diameter D1/D2 and maximum nozzle height H (inch/mm).
H
D2 = min. diameter with Upper Null
Zone adjustment
H
UNZ
D1 = min. diameter
Rigid Twin Lead Flexible Twin Lead Coaxial Single Lead Flexible Single
D1
(1)
4/100 4/100 > Probe diameter 6/150 6/150
D2
(2)
2/50 2/50 > Probe diameter 2/50
(3)
1.5/38
(4)
2/50
H
(5)
4/100 + D
(6)
4/100 + D
(6)
- 4/100 + D
(6)
4/100 + D
(6) (7)
(1) Upper Null Zone=0.
(2) Upper Null Zone>0.
(3) Process connection 1.5 inch.
(4) Process connection 1 inch.
(5) Recommended maximum nozzle height. For coaxial probes there is no limitation on nozzle height.
(6) Nozzle diameter.
(7) For tall nozzles the Long Stud version is recommended (option code LS).