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Instruction Bulletin
Appendix A Rev. 3.9
May 2005
A-8 Appendices Rosemount Analytical Inc. A Division of Emerson Process Management
World Class 3000
d. Snubber Diffusion/Dust Seal Assembly
The snubber diffusion/dust seal assembly,
Figure A-12, is used in applications where
an abrasive shield is to be used with a
snubber type diffusion element. The dust
seal consists of two rings of packing to pre-
vent abrasive dust from collecting inside the
abrasive shield.
Figure A-12. Snubber Diffusion/Dust
Seal Assembly
e. Cup-Type Diffusion Assembly
The cup-type diffusion assembly, Figure
A-13, is used in high-temperature applica-
tions where frequent diffusion element
plugging is a problem. This element may be
used with or without an abrasive shield.
Figure A-13. Cup-Type Diffusion/Dust
Seal Assembly
Figure A-14. Cup-Type Diffusion Assembly
f. Bypass Probe Options
For processes where the flue gas exceeds
the maximum allowable temperature of
1300°F (704°C) a bypass sensor package
can be employed. The bypass system uses
an 18 inch (457 mm) or 3 foot (0.92 m)
probe mounted externally on the stack or
duct. The process or exhaust gases are di-
rected out to the probe through a passive
sampling system using inconel tubes. Flue
gas flow induces the movement of gases
into, through, and out of the bypass unit.
The bypass arrangement does not require
the use of aspiration air and the gas which
flows past the probe is returned to the stack
or duct.
The bypass probe package is normally used
for process temperatures of 1300°F (704°C)
to 2000°F (1094°C). A higher temperature
version of the bypass provides for operation
at temperatures up to 2500°F (1372°C). In
this version the pick up tubes are made of a
special high-temperature alloy.
Overall dimensions and mounting details of
the American and European bypass sys-
tems are shown in Figure A-15.
g. Probe Mounting Jacket Options
A probe mounting jacket option is available to
allow the probe to operate at temperatures of
up to 2000°F (1095°C). A separate Instruction
Bulletin is available for this option.