Reference Manual
00809-0100-4792, Rev CA
August 2010
B-7
Rosemount 1495, 1496
Figure B-3. Orifice Meter Tube Layout for Flanged or Welded Inlet
a
13D
i
allowed for up to =0.54.
b
9.5D
i
allowed for up to =0.47.
c
9.5D
i
allowed for up to =0.46.
S = Separation distance between elbows, measure as defined in Table A-1.
UL1 = UL - UL2. See Figure A-1.
Note 1: Lengths shown under the UL2 column are the dimensions shown in Figure A-1, expressed as the number of published internal
pipe diameters (D
i
) between the downstream end of the 1998 Uniform Concentric 19-Tube Bundle Flow Straightener and the
upstream surface of the orifice plate.
Note 2: The tolerance on specified lengths for UL, UL2, and DL is ±0.25D
i
.
Note 3: Not allowed means that it is not possible to find an acceptable location for the 1998 Uniform Concentric 19-Tube Bundle Flow
Straightener downstream of the particular fitting for all values of UL.
Table B-4. Orifice Meter Installation Requirements With 1998 Uniform Concentric 19-Tube Bundle Flow
Straightener for Meter Tube Upstream Length of .
Single 90° elbow
R/D
i
= 1.5
Two 90° elbows out
of plane
R/D
i
= 1.5
Singe 90° tee
used as an
elbow but not
as a header
element
Partially
closed valves
(at least 50%
open)
High swirl
combined
with single
90° Tee
Any fitting
(catch-all
category)
Downstream
meter tube
length
Diameter Ratio, UL2 UL2 UL2 UL2 UL2 UL2 DL
0.10 5-14.5 5-14.5 5-14.5 5-11 5-13 5-11.5 2.8
0.20 5-14.5 5-14.5 5-14.5 5-11 5-13 5-11.5 2.8
0.30 5-14.5 5-14.5 5-14.5 5-11 5-13 5-11.5 3.0
0.40 5-14.5 5-14.5 5-14.5 5-11 5-13 5-11.5 3.2
0.50 11.5-14.5 9.5-14.5 11-13
b c
3.5
0.60 12-13 13.5-14.5
a
Not allowed
a
Not allowed 3.9
0.67 13 13-14.5 Not allowed Not allowed Not allowed Not allowed 4.2
0.75 14 Not allowed Not allowed Not allowed Not allowed Not allowed 4.5
Recommended
tube bundle
location for
maximum range
of
13 13.5-14.5 13 9.5 13 9.5 4.5
Meter Tube
UL DL
UL1
UL2
Orifice
1998 Uniform Concentric
19-Tube Bundle Flow Straightener
Separation
distance, S
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