Rosemount 1495, Руководство по установке и эксплуатации

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Reference Manual
00809-0100-4792, Rev CA
August 2010
Rosemount 1495, 1496
B-6
UL = Minimum meter tube length upstream of the orifice plate in internal pipe diameter (D
i
). Straight length shall be measured from the down-
stream end of the curved portion of the nearest (or only) elbow or of the tee or the downstream end of the conical portion of reducer or
expander.
DL = Minimum downstream meter tube length in internal pipe diameters (D
i
).
S = Separation distance between piping elements in internal pipe diameter (D
i
) measured from the downstream end of the curved portion of
the upstream elbow to the upstream end of the curved portion of the downstream elbow.
* These installations exhibit the strong effect of Reynolds number and pipe roughness on the recommended length due to the rate of swirl
decay. The present recommendations have been developed for high Reynolds numbers and smooth pipes to capture the worst case.
Note: The tolerance on specified lengths for UL and DL is ±0.25D
i
.
Table B-3. Orifice Meter Installation Requirements Without a Flow Conditioner
Minimum Straight Unobstructed Meter Tube Length from the Upstream Side of the Orifice Plate
(in multiples of published internal pipe diameter, D
i
)
Diameter
ratio
a. Single
90° elbow.
b. Two 90°
elbows in
the same
plane with
S > 30D
i
.
c. Two 90°
elbows in
perpendicu
lar planes
with
S>15D
i
.
Two 90°
elbows in
the same
plane “S”
configura
tion
spacer
.
Two 90°
elbows in the
same plane,
“S”
configuration
spacer
Two 90°
elbows in
perpendi
cular
planes,
*
Two 90°
elbows in
perpendicular
planes,
Single
90° Tee
used as
an
elbow
but not
as a
header
element
a. Single
45° elbow.
b. Two 45°
elbows in
the same
plane “S”
configurati
on Gate
valve at
least
50%
open
Con-
centric
reducer
Any other
configuration
(catch all
category)*
Downstream
tube length
UL UL UL UL UL UL UL UL UL UL DL
6 10 10 50 19 9 30 17 6 70 2.8
0.30 11 10 12 50 32 9 30 19 6 108 3.0
0.40 16 10 13 50 44 9 30 21 6 145 3.2
0.50 30 30 18 95 44 19 30 25 7 145 3.5
0.60 44 44 30 95 44 29 30 30 9 145 3.9
0.67 44 44 44 95 44 36 44 35 11 145 4.2
0.75 44 44 44 95 44 44 44 44 13 145 4.5
Recomm
ended
length for
maximum
range
44 44 44 95 44 44 44 44 13 145 4.5

S 10D
i

0D
i
S 30D
 
S 5D
i

5D
i
S 15D
 
S 22D
i


0.20


0.75
