McCrometer V-Cone Owner's manual
Advanced
Dierential
Pressure
Flowmeter
Technology
INSTALLATION
OPERATION &
MAINTENANCE
MANUAL
Lit. # 24509-15, Rev. 4.3
August 31, 2017
The V-Cone Installation, Operation & Maintenance Manual is also available in Spanish, French and Portuguese on the McCrometer
website.
www.mccrometer.com
24509-23 V-Cone IOM Manual (Spanish) http://www.mccrometer.com/library/pdf/24509-23.pdf
24508-87 V-Cone IOM Manual (French) http://www.mccrometer.com/library/pdf/24508-87.pdf
24519-23 V-Cone IOM Manual (Portuguese) http://www.mccrometer.com/library/pdf/24519-23.pdf
Copyright © 1992-2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative for
current technical data and instructions.
1.1 Introduction ........................................1
1.2 Principles Of Operation .............................1
1.3 Reshaping The Velocity Prole.......................1
2
2.1 High Accuracy ......................................2
2.2 Repeatability .......................................2
2.3 Turndown ..........................................2
2.4 Installation Requirements ...........................3
2.5 Long Term Performance.............................3
2.6 Signal Stability......................................3
2.7 Low Permanent Pressure Loss .......................3
2.8 Sizing ..............................................4
2.9 No Areas of Stagnation..............................4
2.10 Mixing..............................................4
2.11 V-Cone Models .....................................4
5
3.1 Application Data....................................5
3.2 Flow Calculations ...................................5
3.3 Simplied Liquid Calculation . . . . . . . . . . . . . . . . . . . . . . . . 7
3.4 Application Sizing ..................................8
3.5 Calibration..........................................8
3.6 Materials Of Construction ...........................8
3.7 Valve Manifolds .....................................8
3.8 Secondary And Tertiary Instrumentation.............9
3.9 Meter Tag...........................................9
4.1 Scope .............................................10
4.2 Safety .............................................10
4.3 Unpacking.........................................10
4.4 Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
4.5 Piping Specication................................10
4.6 Piping Requirements...............................11
4.7 Isolation (Block) Valves .............................11
4.8 Valve Manifolds ....................................11
4.9 Installation ........................................12
4.10 Pressure Taps ......................................12
4.11 Remote Seals or Chemical Seals ....................13
4.12 Impulse Line: General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
4.13 Impulse Line: Process Industries . . . . . . . . . . . . . . . . . . . .13
4.14 Impulse Line: Steam Applications...................13
4.15 Insulation..........................................13
4.16 Horizontal Piping Installations: Gas .................14
4.17 Horizontal Piping Installations: Liquids..............15
4.18 Horizontal Piping Installations: Condensing Vapors . 15
4.19 Vertical Piping Installations: General ................16
4.20 Vertical Piping Installations: Up Flow ...............16
4.21 Vertical Piping Installations: Gas ...................16
4.22 Vertical Piping Installations: Liquids ................17
4.23 Vertical Piping Installations: Condensing vapors, i.e.
steam .............................................18
4.24 Calibration Compensated Installation...............18
4.25 Vertical Down Flow Piping Installations: General ....18
4.26 Vertical Down Flow Piping Installations: Gas ........19
4.27 Vertical Down Flow Piping Installations: Liquids ....20
4.28 Vertical Down Flow Piping Installations: Condensing
Vapors, i.e. Steam ..................................21
4.29 Supporting Manifold Blocks and Dual Transmitters..22
4.30 Zeroing DP Pressure Transmitters Following
Installation For Steam Flow Applications............23
4.31 Zeroing DP Pressure Transmitters Following Installation
For Ambient Temperature Liquid Applications ......23
4.32 Zeroing DP Pressure Transmitters Following
Installation For Gas Applications....................24
4.33 Zeroing Low Range Transmitters ...................24
4.34 Dierential Pressure Measurement .................25
4.35 Temperature And Pressure Measurement ...........25
5.1 Face To Face Dimensions ...........................26
5.2 Face To Face Dimensions ...........................26
6.1 Wafer-Cone©Model Template ......................27
6.2 Precision Tube V-Cone Model Template .............27
6.3 V-Cone Special Models.............................28
6.4 V-Cone Materials...................................28
7.1 Periodic Maintenance ..............................29
8.1 Troubleshooting A V-Cone System On-Site..........29
32
9.1 Conguration Sheets of Various V-Cone Models .....32
33
10.1 V-Cone Installation Guide: Upstream and Downstream
Minimum Straight Pipe Run Recommendations.....33
35
General
Copyright © 2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
1
The McCrometer V-Cone®Flowmeter is a patented technology that accurately measures ow over a
wide range of Reynolds numbers, under all kinds of conditions and for a variety of uids. It operates
on the same physical principle as other dierential pressure-type owmeters, using the theorem
of conservation of energy in uid ow through a pipe. The V-Cone’s remarkable performance
characteristics, however, are the result of its unique design. It features a centrally-located cone inside
the tube. The cone interacts with the uid ow, reshaping the uid’s velocity prole and creating
a region of lower pressure immediately downstream of itself. The pressure dierence, exhibited
between the static line pressure and the low pressure created downstream of the cone, can be
measured via two pressure sensing taps. One tap is placed slightly upstream of the cone, the other is
located in the downstream face of the cone itself. The pressure dierence can then be incorporated
into a derivation of the Bernoulli equation to determine the uid ow rate. The cone’s central position
in the line optimizes the velocity prole of the ow at the point of measurement, assuring highly
accurate, reliable ow measurement regardless of the condition of the ow upstream of the meter.
Principles Of Operation
The V-Cone is a dierential pressure type owmeter. Basic theories behind dierential pressure type
owmeters have existed for over a century. The principal theory among these is Bernoulli’s theorem
for the conservation of energy in a closed pipe. This states
that for a constant ow, the pressure in a pipe is inversely
proportional to the square of the velocity in the pipe.
Simply, the pressure decreases as the velocity increases.
For instance, as the uid approaches the V-Cone meter, it
will have a pressure of P1. As the uid velocity increases
at the constricted area of the V-Cone, the pressure drops
to P2, as shown in Figure 1. Both P1and P2are measured
at the V-Cone’s taps using a variety of dierential pressure
transducers. The Dp created by a V-Cone will increase and
decrease exponentially with the ow velocity. As the constriction takes up more of the pipe cross-
sectional area, more dierential pressure will be created at the same owrates. The beta ratio equals
the ow area at the largest cross section of the cone (converted to an equivalent diameter) divided
by the meter’s inside diameter (see section 3.2).
The V-Cone is similar to other dierential pressure (Dp) meters in
the equations of ow that it uses. V-Cone geometry, however, is
quite dierent from traditional Dp meters. The V-Cone constricts
the ow by positioning a cone in the center of the pipe.
This forces the ow in the center of the pipe to ow around
the cone. This geometry presents many advantages over the
traditional concentric Dp meter. The actual shape of the cone
has been continuously evaluated and tested for over ten years to
provide the best performance under diering circumstances.
One must understand the idea of a ow prole in a pipe to
understand the performance of the V-Cone. If the ow in a long
pipe is not subject to any obstructions or disturbances, it is well-developed ow. If a line passes
across the diameter of this well-developed ow, the velocity at each point on that line would be
dierent. The velocity would be zero at the wall of the pipe, maximum at the center of the pipe, and
zero again at the opposite wall. This is due to friction at the pipe walls that slows the uid as it passes.
Since the cone is suspended in the center of the pipe, it interacts directly with the “high velocity
core” of the ow. The cone forces the high velocity core to mix with the lower velocity ows closer
to the pipe walls. Other Dp meters have centrally located openings and do not interact with this
high velocity core. This is an important advantage to the V-Cone at lower owrates. As the owrate
Dp
Low
Pressure
Port
H
L
Zero Velocity
Fluid
Velocity
Maximum
Velocity
General
Features
Copyright © 2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
2
decreases, the V-Cone continues to interact with the highest velocity in the pipe. Other Dp meters
may lose their useful Dp signal at ows where the V-Cone can still produce one.
The pipe ow prole in actual installations is rarely ideal. There are many installations where a
owmeter exists in ow that is not well developed. Practically any changes to the piping, such as
elbows, valves, reductions, expansions, pumps, and tees can disturb well-developed ow. Trying to
measure disturbed ow can create substantial errors for other owmeter technologies. The V-Cone
overcomes this by reshaping the velocity prole upstream of the cone. This is a benet derived from
the cone’s contoured shape and position in the line. As the ow approaches the cone, the ow prole
“attens” toward the shape of a well-developed prole.
The V-Cone can atten the ow prole under extreme conditions, such as a single elbow or double
elbows out-of-plane, positioned closely upstream of the meter. This means that as dierent ow
proles approach the cone, there will always be a predictable ow prole at the cone. This ensures
accurate measurement even in non-ideal conditions.
The V-Cone primary element can be accurate to ±0.5% of ow rate reading and the Wafer-Cone®can
be accurate to ±1.0%. The level of accuracy is dependent to a degree on application parameters and
secondary instrumentation.
Accuracy statements of percent of actual ow rate means that the measurement uncertainty is within the
given percent value within the stated range for the owmeter.
The V-Cone and the Wafer-Cone primary elements exhibit excellent repeatability of ±0.1% or better.
Repeatability is a owmeter’s ability to repeat it’s accuracy at a given ow rate.
Turndown
The turndown of the V-Cone can reach far beyond traditional Dp meters. A typical turndown for a
V-Cone is 10 to 1. Greater turndowns are attainable. Flows with Reynolds numbers as low as 8000 will
produce a linear signal. Lower Reynolds number ranges are measurable and are repeatable by applying
a curve t to the measured Dp, derived from calibration over a specic Reynolds number range.
Irregular profile
caused by a disturbance
upstream
Flattened profile
caused by the
V-Cone
Features
Features
Copyright © 2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
3
Since the V-Cone can atten the velocity prole, it can function much closer to upstream disturbances
than other Dp meters. The recommended installation for the V-Cone is zero to three diameters of
straight run upstream and zero to one diameter downstream. This can be a major benet to users
with larger, more expensive line sizes or users which have small run lengths. McCrometer conducted
performance tests of the V-Cone downstream of a single 90°elbow and two close coupled 90°elbows
out of plane. These tests show that the V-Cone can be installed adjacent to either single elbows or
two elbows out of plane without sacricing accuracy.
For specic installation recommendations, see appendices.
V-Cone
Orice Plate
The contoured shape of the cone constricts the ow without impacting the ow against an abrupt
surface. A boundary layer forms along the cone and directs the uid away from the beta edge. This
means the beta edge will not be as subject to the usual wear by unclean uids, as is the case with
an orice plate. The beta ratio will then remain unchanged and the calibration of the meter will be
accurate for a much longer time.
Every Dp meter has a “signal bounce”. This means that even
in steady ow, the signal generated by the primary element
will uctuate a certain amount. On a typical orice plate, the
vortices that form just after the plate are long. These long
vortices create a high amplitude, low frequency signal from
the orice plate. This could disturb the Dp readings from
the meter. The V-Cone forms very short vortices as the ow
passes the cone. These short vortices create a low amplitude,
high frequency signal. This translates into a signal with high
stability from the V-Cone. Representative signals from a
V-Cone and from a typical orice plate are shown in Figure 6.
Without the impact of an abrupt surface, the permanent pressure loss is lower than a typical orice
plate meter. Also, the signal stability of the V-Cone allows the recommended full scale Dp signal to be
lower for the V-Cone than other Dp meters. This will lower the permanent pressure loss.
Features
Copyright © 2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
4
Sizing
The unique geometry of the V-Cone allows for a wide range of beta ratios. Standard beta ratios range
from 0.45, 0.55, 0.65, 0.75, and 0.80.
No Areas of Stagnation
The “swept through” design of the cone does not allow for areas of stagnation where debris,
condensation or particles from the uid could accumulate.
The short vortices described in section 2.6 mix the uid thoroughly just downstream of the cone. The
V-Cone is currently used in many applications as a static mixer where instant and complete mixing
are necessary.
McCrometer oers two types of V-Cone primary elements: the precision tube V-Cone and the Wafer-
Cone. Precision tube V-Cones range in line sizes from ½” to 150” and larger and Wafer-Cones range
from 1”to 6”.
Flow
HL
Flow
the V-Cone Flow MeasureMent systeM
Copyright © 2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
5
Application Data
The customer must provide application parameters so that the appropriate V-Cone owmeter may
be selected. McCrometer has an extensive meter performance database of uid properties which
can be utilized for sizing purposes.
Nomenclature
Symbol Description English Units Metric Units
αMaterial Thermal Expansion αor αcone, αpipe
(alpha) ˚R-1 ˚R-1
βBeta Ratio - -
CDFlowmeter Coecient - -
d Cone Outside Diameter in mm
D Pipe Inside Diameter in mm
∆P Dierential Pressure (DP) inWC mbar
∆Pmax Maximum Dierential Pressure on Sizing See note 4 See note 4
FaMaterial Thermal Expansion Factor - -
k Gas Isentropic Exponent - -
k1Flow Constant
3.2 Flow Calculations
Nomenclature:
Symbol Description English Units Metric Units
α Material Thermal Expansion α
or α
cone
, α
pipe
(alpha) °R
-1
°R
-1
β Beta Ratio - -
C
D
Flowmeter Coefficient - -
d Cone Outside Diameter in mm
D Pipe Inside Diameter in mm
ΔP Differential Pressure (dp) inWC mbar
ΔP
max
Maximum Differential
Pressure on Sizing See note 4 See note 4
F
a
Material Thermal Expansion
Factor - -
k Gas Isentropic Exponent - -
k
1
Flow Constant
inWCs
ftlbm
⋅
⋅
2
3
mbars
mkg
⋅
⋅
2
3
k
2
Simplified Liquid Flow
Constant See note 4 See note 4
μ Viscosity cP cP
P Operating Pressure psiA barA
P
b
Base Pressure psiA barA
Q Actual Volume Flow ACFS m
3
/s
Q
max
Maximum Flowrate on Sizing See note 4 See note 4
Q
STD
Standard Gas Volume Flow SCFS Nm
3
/s
Re Reynolds Number - -
ρ Flowing Density (rho) lbm/ft
3
kg/m
3
ρ
water
Water Density 62.3663 lbm/ft
3
999.012 kg/m
3
S
g
Specific Gravity of the Gas - -
S
L
Specific Gravity of the Liquid - -
T Operating Temperature °R K
T
b
Base Temperature °R K
T
d
Deviation from Standard
Temperature (°R) 67.527−= TTd67.527
5
9−= TT
d
U
1
Unit Conversion 0.0360912 psiA/inWC 0.001 barA/mbar
U
2
Unit Conversion 144 in
2
/ft
2
1,000,000 mm
2
/m
2
U
3
Unit Conversion 167.213 lbm /s
2
ft
inWC 100 kg/m s
2
mbar
U
4
Unit Conversion 124.0137 cP ft s / lbm 1
U
5
Unit Conversion 2.6988 °R lbm / ft
3
psiA
348.338 K kg / m
3
barA
v Velocity ft/s m/s
Y Gas Expansion Factor - -
Z Gas Compressibility - -
Z
b
Base Gas Compressibility - -
3.2 Flow Calculations
Nomenclature:
Symbol Description English Units Metric Units
α Material Thermal Expansion α
or α
cone
, α
pipe
(alpha) °R
-1
°R
-1
β Beta Ratio - -
C
D
Flowmeter Coefficient - -
d Cone Outside Diameter in mm
D Pipe Inside Diameter in mm
ΔP Differential Pressure (dp) inWC mbar
ΔP
max
Maximum Differential
Pressure on Sizing See note 4 See note 4
F
a
Material Thermal Expansion
Factor - -
k Gas Isentropic Exponent - -
k
1
Flow Constant
inWCs
ftlbm
⋅
⋅
2
3
mbars
mkg
⋅
⋅
2
3
k
2
Simplified Liquid Flow
Constant See note 4 See note 4
μ Viscosity cP cP
P Operating Pressure psiA barA
P
b
Base Pressure psiA barA
Q Actual Volume Flow ACFS m
3
/s
Q
max
Maximum Flowrate on Sizing See note 4 See note 4
Q
STD
Standard Gas Volume Flow SCFS Nm
3
/s
Re Reynolds Number - -
ρ Flowing Density (rho) lbm/ft
3
kg/m
3
ρ
water
Water Density 62.3663 lbm/ft
3
999.012 kg/m
3
S
g
Specific Gravity of the Gas - -
S
L
Specific Gravity of the Liquid - -
T Operating Temperature °R K
T
b
Base Temperature °R K
T
d
Deviation from Standard
Temperature (°R) 67.527−= TTd67.527
5
9−= TT
d
U
1
Unit Conversion 0.0360912 psiA/inWC 0.001 barA/mbar
U
2
Unit Conversion 144 in
2
/ft
2
1,000,000 mm
2
/m
2
U
3
Unit Conversion 167.213 lbm /s
2
ft
inWC 100 kg/m s
2
mbar
U
4
Unit Conversion 124.0137 cP ft s / lbm 1
U
5
Unit Conversion 2.6988 °R lbm / ft
3
psiA
348.338 K kg / m
3
barA
v Velocity ft/s m/s
Y Gas Expansion Factor - -
Z Gas Compressibility - -
Z
b
Base Gas Compressibility - -
k2Simplied Liquid Flow Constant See note 4 See note 4
μViscosity cP cP
P Operating Pressure psiA barA
PbBase Pressure psiA barA
QActual Volume Flow ACFS m3/s
Qmax Maximum Flowrate on Sizing See note 4 See note 4
QSTD Standard Gas Volume Flow SCFS Nm3/s
Re Reynolds Number - -
ρFlowing Density (rho) lbm/ft3kg/m3
ρ
water
Water Density 62.3663 lbm/ft3999.012 kg/m3
SgSpecic Gravity of the Gas - -
SLSpecic Gravity of the Liquid - -
TOperating Temperature ˚R K
TbBase Temperature ˚R K
TdDeviation from Standard Temperature (°R) Td= T - 527.67 Td= T - 527.67
U1Unit Conversion 0.0360912 psiA/inWC 0.001 barA/mbar
U2Unit Conversion 144 in2/ft21,000,000 mm2/m2
U3Unit Conversion 167.213 lbm /s2 ft inWC 100 kg/m s2mbar
U4Unit Conversion 124.0137 cP ft s / lbm 1
U5Unit Conversion 2.6988 ˚R lbm / ft3psiA 348.338 K kg / m3barA
v Velocity ft/s m/s
Y Gas Expansion Factor - -
Z Gas Compressibility - -
ZbBase Gas Compressibility - -
Flow
System
the V-Cone Flow MeasureMent systeM
Copyright © 2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
6
General Flow Calculations (continued)
V-Cone Beta
Ratio
3.2.1 V-Cone Beta
Ratio
2
2
1
D
d
−=
β
βfrom sizing
report
3.2.2 Flow
Constant 4
22
2
3
11
4
2
β
β
π
−
⋅
⋅
⋅
⋅⋅
=D
U
U
k
3.2.3
Material
Thermal
Expansion
Factor
da TF ⋅⋅+=
α
21 See note 1.
3.2.4
Material
Thermal
Expansion
Factor
If cone and
main pipe are
made of
different
materials
()
[]
()
[]
22
22
11 dTDT
dD
F
dconedpipe
a⋅⋅−−⋅⋅−
−
=
αα
See note 1.
3.2.5 Pipeline
Velocity 2
2
4
D
QU
v⋅
⋅⋅
=
π
3.2.6 Reynolds
Number
μ
ρ
⋅⋅
=Dv
U4
Re
Dimensionless
number which
can be used to
correlate meter
calibration in
different fluids
3.2.7
V-Cone Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
4)696.0649.0(1
β
For Liquids Y = 1
3.2.8
Wafer Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
8)78.6755.0(1
β
For Liquids Y = 1
3.2.9 Liquid Density Lwater S⋅=
ρ
ρ
3.2.10 Gas Density TZ
PS
Ug
⋅
⋅
=5
ρ
3.2.11
Actual
Volume
Flowrate
ρ
P
kYCFQ Da
Δ
⋅⋅⋅⋅= 1See notes 2, 3 &
5
3.2.12
Standard Gas
Volume
Flowrate ⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅⋅
⋅⋅
⋅= ZTP
ZTP
QQ
b
bb
STD
Converts actual
flow to standard
flow at base
conditions
βfrom sizing
report
Flow Constant
3.2.1 V-Cone Beta
Ratio 2
2
1D
d
−=
β
βfrom sizing
report
3.2.2 Flow
Constant
4
22
2
3
11
4
2
β
β
π
−
⋅
⋅
⋅
⋅⋅
=D
U
U
k
3.2.3
Material
Thermal
Expansion
Factor
da TF ⋅⋅+=
α
21 See note 1.
3.2.4
Material
Thermal
Expansion
Factor
If cone and
main pipe are
made of
different
materials
()
[]
()
[]
22
22
11 dTDT
dD
F
dconedpipe
a⋅⋅−−⋅⋅−
−
=
αα
See note 1.
3.2.5 Pipeline
Velocity 2
2
4
D
QU
v⋅
⋅⋅
=
π
3.2.6 Reynolds
Number
μ
ρ
⋅⋅
=Dv
U4
Re
Dimensionless
number which
can be used to
correlate meter
calibration in
different fluids
3.2.7
V-Cone Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
4)696.0649.0(1
β
For Liquids Y = 1
3.2.8
Wafer Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
8)78.6755.0(1
β
For Liquids Y = 1
3.2.9 Liquid Density Lwater S⋅=
ρ
ρ
3.2.10 Gas Density TZ
PS
Ug
⋅
⋅
=5
ρ
3.2.11
Actual
Volume
Flowrate
ρ
P
kYCFQ Da
Δ
⋅⋅⋅⋅= 1See notes 2, 3 &
5
3.2.12
Standard Gas
Volume
Flowrate ⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅⋅
⋅⋅
⋅= ZTP
ZTP
QQ
b
bb
STD
Converts actual
flow to standard
flow at base
conditions
Material Thermal
Expansion
Factor
Fa = 1 + 2 · α · TdSee note 1
Material Thermal
Expansion Factor
if cone and main
pipe are made
of dierent
materials
3.2.1 V-Cone Beta
Ratio 2
2
1D
d
−=
β
βfrom sizing
report
3.2.2 Flow
Constant 4
22
2
3
11
4
2
β
β
π
−
⋅
⋅
⋅
⋅⋅
=D
U
U
k
3.2.3
Material
Thermal
Expansion
Factor
da TF ⋅⋅+=
α
21 See note 1.
3.2.4
Material
Thermal
Expansion
Factor
If cone and
main pipe are
made of
different
materials
()
[]
()
[]
22
22
11 dTDT
dD
F
dconedpipe
a⋅⋅−−⋅⋅−
−
=
αα
See note 1.
3.2.5 Pipeline
Velocity 2
2
4
D
QU
v⋅
⋅⋅
=
π
3.2.6 Reynolds
Number
μ
ρ
⋅⋅
=Dv
U4
Re
Dimensionless
number which
can be used to
correlate meter
calibration in
different fluids
3.2.7
V-Cone Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
4)696.0649.0(1
β
For Liquids Y = 1
3.2.8
Wafer Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
8)78.6755.0(1
β
For Liquids Y = 1
3.2.9 Liquid Density Lwater S⋅=
ρ
ρ
3.2.10 Gas Density TZ
PS
Ug
⋅
⋅
=5
ρ
3.2.11
Actual
Volume
Flowrate
ρ
P
kYCFQ Da
Δ
⋅⋅⋅⋅= 1See notes 2, 3 &
5
3.2.12
Standard Gas
Volume
Flowrate ⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅⋅
⋅⋅
⋅= ZTP
ZTP
QQ
b
bb
STD
Converts actual
flow to standard
flow at base
conditions
See note 1
Pipeline Velocity
3.2.1 V-Cone Beta
Ratio 2
2
1D
d
−=
β
βfrom sizing
report
3.2.2 Flow
Constant 4
22
2
3
11
4
2
β
β
π
−
⋅
⋅
⋅
⋅⋅
=D
U
U
k
3.2.3
Material
Thermal
Expansion
Factor
da TF ⋅⋅+=
α
21 See note 1.
3.2.4
Material
Thermal
Expansion
Factor
If cone and
main pipe are
made of
different
materials
()
[]
()
[]
22
22
11 dTDT
dD
F
dconedpipe
a⋅⋅−−⋅⋅−
−
=
αα
See note 1.
3.2.5 Pipeline
Velocity
2
2
4
D
QU
v
⋅
⋅⋅
=
π
3.2.6 Reynolds
Number
μ
ρ
⋅⋅
=Dv
U4
Re
Dimensionless
number which
can be used to
correlate meter
calibration in
different fluids
3.2.7
V-Cone Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
4)696.0649.0(1
β
For Liquids Y = 1
3.2.8
Wafer Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
8)78.6755.0(1
β
For Liquids Y = 1
3.2.9 Liquid Density Lwater S⋅=
ρ
ρ
3.2.10 Gas Density TZ
PS
Ug
⋅
⋅
=5
ρ
3.2.11
Actual
Volume
Flowrate
ρ
P
kYCFQ Da
Δ
⋅⋅⋅⋅= 1See notes 2, 3 &
5
3.2.12
Standard Gas
Volume
Flowrate ⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅⋅
⋅⋅
⋅= ZTP
ZTP
QQ
b
bb
STD
Converts actual
flow to standard
flow at base
conditions
Reynolds
Number
3.2.1 V-Cone Beta
Ratio 2
2
1D
d
−=
β
βfrom sizing
report
3.2.2 Flow
Constant 4
22
2
3
11
4
2
β
β
π
−
⋅
⋅
⋅
⋅⋅
=D
U
U
k
3.2.3
Material
Thermal
Expansion
Factor
da TF ⋅⋅+=
α
21 See note 1.
3.2.4
Material
Thermal
Expansion
Factor
If cone and
main pipe are
made of
different
materials
()
[]
()
[]
22
22
11 dTDT
dD
F
dconedpipe
a⋅⋅−−⋅⋅−
−
=
αα
See note 1.
3.2.5 Pipeline
Velocity 2
2
4
D
QU
v⋅
⋅⋅
=
π
3.2.6 Reynolds
Number
μ
ρ
⋅⋅
=Dv
U4
Re
Dimensionless
number which
can be used to
correlate meter
calibration in
different fluids
3.2.7
V-Cone Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
4)696.0649.0(1
β
For Liquids Y = 1
3.2.8
Wafer Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
8)78.6755.0(1
β
For Liquids Y = 1
3.2.9 Liquid Density Lwater S⋅=
ρ
ρ
3.2.10 Gas Density TZ
PS
Ug
⋅
⋅
=5
ρ
3.2.11
Actual
Volume
Flowrate
ρ
P
kYCFQ Da
Δ
⋅⋅⋅⋅= 1See notes 2, 3 &
5
3.2.12
Standard Gas
Volume
Flowrate ⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅⋅
⋅⋅
⋅= ZTP
ZTP
QQ
b
bb
STD
Converts actual
flow to standard
flow at base
conditions
Dimensionless
number which
can be used to
correlate meter
calibration in
dierent uids
V-Cone Gas
Expansion
Factor
3.2.1 V-Cone Beta
Ratio 2
2
1D
d
−=
β
βfrom sizing
report
3.2.2 Flow
Constant 4
22
2
3
11
4
2
β
β
π
−
⋅
⋅
⋅
⋅⋅
=D
U
U
k
3.2.3
Material
Thermal
Expansion
Factor
da TF ⋅⋅+=
α
21 See note 1.
3.2.4
Material
Thermal
Expansion
Factor
If cone and
main pipe are
made of
different
materials
()
[]
()
[]
22
22
11 dTDT
dD
F
dconedpipe
a⋅⋅−−⋅⋅−
−
=
αα
See note 1.
3.2.5 Pipeline
Velocity 2
2
4
D
QU
v⋅
⋅⋅
=
π
3.2.6 Reynolds
Number
μ
ρ
⋅⋅
=Dv
U4
Re
Dimensionless
number which
can be used to
correlate meter
calibration in
different fluids
3.2.7
V-Cone Gas
Expansion
Factor Pk
PU
Y
⋅
Δ⋅
⋅+−= 1
4)696.0649.0(1
β
For Liquids Y = 1
3.2.8
Wafer Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
8)78.6755.0(1
β
For Liquids Y = 1
3.2.9 Liquid Density Lwater S⋅=
ρ
ρ
3.2.10 Gas Density TZ
PS
Ug
⋅
⋅
=5
ρ
3.2.11
Actual
Volume
Flowrate
ρ
P
kYCFQ Da
Δ
⋅⋅⋅⋅= 1See notes 2, 3 &
5
3.2.12
Standard Gas
Volume
Flowrate ⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅⋅
⋅⋅
⋅= ZTP
ZTP
QQ
b
bb
STD
Converts actual
flow to standard
flow at base
conditions
For Liquids Y = 1
Wafer Gas
Expansion
Factor
3.2.1 V-Cone Beta
Ratio 2
2
1D
d
−=
β
βfrom sizing
report
3.2.2 Flow
Constant 4
22
2
3
11
4
2
β
β
π
−
⋅
⋅
⋅
⋅⋅
=D
U
U
k
3.2.3
Material
Thermal
Expansion
Factor
da TF ⋅⋅+=
α
21 See note 1.
3.2.4
Material
Thermal
Expansion
Factor
If cone and
main pipe are
made of
different
materials
()
[]
()
[]
22
22
11 dTDT
dD
F
dconedpipe
a⋅⋅−−⋅⋅−
−
=
αα
See note 1.
3.2.5 Pipeline
Velocity 2
2
4
D
QU
v⋅
⋅⋅
=
π
3.2.6 Reynolds
Number
μ
ρ
⋅⋅
=Dv
U4
Re
Dimensionless
number which
can be used to
correlate meter
calibration in
different fluids
3.2.7
V-Cone Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
4)696.0649.0(1
β
For Liquids Y = 1
3.2.8
Wafer Gas
Expansion
Factor Pk
PU
Y
⋅
Δ⋅
⋅+−= 1
8)78.6755.0(1
β
For Liquids Y = 1
3.2.9 Liquid Density Lwater S⋅=
ρ
ρ
3.2.10 Gas Density TZ
PS
Ug
⋅
⋅
=5
ρ
3.2.11
Actual
Volume
Flowrate
ρ
P
kYCFQ Da
Δ
⋅⋅⋅⋅= 1See notes 2, 3 &
5
3.2.12
Standard Gas
Volume
Flowrate ⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅⋅
⋅⋅
⋅= ZTP
ZTP
QQ
b
bb
STD
Converts actual
flow to standard
flow at base
conditions
For Liquids Y = 1
Liquid Density ρ = ρágua · SL
Gas Density
3.2.1 V-Cone Beta
Ratio 2
2
1D
d
−=
β
βfrom sizing
report
3.2.2 Flow
Constant 4
22
2
3
11
4
2
β
β
π
−
⋅
⋅
⋅
⋅⋅
=D
U
U
k
3.2.3
Material
Thermal
Expansion
Factor
da TF ⋅⋅+=
α
21 See note 1.
3.2.4
Material
Thermal
Expansion
Factor
If cone and
main pipe are
made of
different
materials
()
[]
()
[]
22
22
11 dTDT
dD
F
dconedpipe
a⋅⋅−−⋅⋅−
−
=
αα
See note 1.
3.2.5 Pipeline
Velocity 2
2
4
D
QU
v⋅
⋅⋅
=
π
3.2.6 Reynolds
Number
μ
ρ
⋅⋅
=Dv
U4
Re
Dimensionless
number which
can be used to
correlate meter
calibration in
different fluids
3.2.7
V-Cone Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
4)696.0649.0(1
β
For Liquids Y = 1
3.2.8
Wafer Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
8)78.6755.0(1
β
For Liquids Y = 1
3.2.9 Liquid Density Lwater S⋅=
ρ
ρ
3.2.10 Gas Density TZ
PS
Ug
⋅
⋅
=5
ρ
3.2.11
Actual
Volume
Flowrate
ρ
P
kYCFQ Da
Δ
⋅⋅⋅⋅= 1See notes 2, 3 &
5
3.2.12
Standard Gas
Volume
Flowrate ⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅⋅
⋅⋅
⋅= ZTP
ZTP
QQ
b
bb
STD
Converts actual
flow to standard
flow at base
conditions
Actual Volume
Flowrate
3.2.1 V-Cone Beta
Ratio 2
2
1D
d
−=
β
βfrom sizing
report
3.2.2 Flow
Constant 4
22
2
3
11
4
2
β
β
π
−
⋅
⋅
⋅
⋅⋅
=D
U
U
k
3.2.3
Material
Thermal
Expansion
Factor
da TF ⋅⋅+=
α
21 See note 1.
3.2.4
Material
Thermal
Expansion
Factor
If cone and
main pipe are
made of
different
materials
()
[]
()
[]
22
22
11 dTDT
dD
F
dconedpipe
a⋅⋅−−⋅⋅−
−
=
αα
See note 1.
3.2.5 Pipeline
Velocity 2
2
4
D
QU
v⋅
⋅⋅
=
π
3.2.6 Reynolds
Number
μ
ρ
⋅⋅
=Dv
U4
Re
Dimensionless
number which
can be used to
correlate meter
calibration in
different fluids
3.2.7
V-Cone Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
4)696.0649.0(1
β
For Liquids Y = 1
3.2.8
Wafer Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
8)78.6755.0(1
β
For Liquids Y = 1
3.2.9 Liquid Density Lwater S⋅=
ρ
ρ
3.2.10 Gas Density TZ
PS
Ug
⋅
⋅
=5
ρ
3.2.11
Actual
Volume
Flowrate
ρ
P
kYCFQ Da
Δ
⋅⋅⋅⋅= 1
See notes 2, 3 &
5
3.2.12
Standard Gas
Volume
Flowrate ⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅⋅
⋅⋅
⋅= ZTP
ZTP
QQ
b
bb
STD
Converts actual
flow to standard
flow at base
conditions
See notes 2, 3 & 5
Standard Gas
Volume Flowrate
3.2.1 V-Cone Beta
Ratio 2
2
1D
d
−=
β
βfrom sizing
report
3.2.2 Flow
Constant 4
22
2
3
11
4
2
β
β
π
−
⋅
⋅
⋅
⋅⋅
=D
U
U
k
3.2.3
Material
Thermal
Expansion
Factor
da TF ⋅⋅+=
α
21 See note 1.
3.2.4
Material
Thermal
Expansion
Factor
If cone and
main pipe are
made of
different
materials
()
[]
()
[]
22
22
11 dTDT
dD
F
dconedpipe
a⋅⋅−−⋅⋅−
−
=
αα
See note 1.
3.2.5 Pipeline
Velocity 2
2
4
D
QU
v⋅
⋅⋅
=
π
3.2.6 Reynolds
Number
μ
ρ
⋅⋅
=Dv
U4
Re
Dimensionless
number which
can be used to
correlate meter
calibration in
different fluids
3.2.7
V-Cone Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
4)696.0649.0(1
β
For Liquids Y = 1
3.2.8
Wafer Gas
Expansion
Factor Pk
PU
Y⋅
Δ⋅
⋅+−= 1
8)78.6755.0(1
β
For Liquids Y = 1
3.2.9 Liquid Density Lwater S⋅=
ρ
ρ
3.2.10 Gas Density TZ
PS
Ug
⋅
⋅
=5
ρ
3.2.11
Actual
Volume
Flowrate
ρ
P
kYCFQ Da
Δ
⋅⋅⋅⋅= 1See notes 2, 3 &
5
3.2.12
Standard Gas
Volume
Flowrate
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⋅⋅
⋅⋅
⋅= ZTP
ZTP
QQ
b
bb
STD
Converts actual
flow to standard
flow at base
conditions
Converts actual
ow to standard
ow at base
conditions
the V-Cone Flow MeasureMent systeM
Copyright © 2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
7
Simplied Liquid Flow
Constant
3.3 Simplified Liquid Calculation
3.3.1
Simplified
Liquid Flow
Constant
max
max
2P
Q
kΔ
=
See note 4
3.3.2
Simplified
Liquid
Flowrate
PkQ Δ= 2 See note 4
See note 4
Simplied Liquid Flowrate
3.3 Simplified Liquid Calculation
3.3.1
Simplified
Liquid Flow
Constant max
max
2P
Q
kΔ
= See note 4
3.3.2
Simplified
Liquid
Flowrate
PkQ Δ= 2
See note 4
See note 4
1. Material Thermal Expansion – The thermal expansion equations correct for dimensional changes
which occur as the operating temperature deviates from the base temperature of 68° F (see 3.2.3
and 3.2.4) The Fafactor can be excluded from the ow equation if the operating temperature is:
< 100° Fahrenheit , < 559.67° Rankine , < 37.78° Celsius, < 310.93 K.
If the Fafactor is signicant and the operating temperature is stable then a constant Favalue
can be used. If the Fafactor is signicant and the temperature varies then an Fafactor should be
calculated prior to every ow calculation.
2. Discharge Coecient – Discharge coecients can be implemented in the ow equations via
several dierent methods. Typical methods are average CD, CDlook up table, or CDtted data.
If a CDlook up table or tted data is utilized additional calculations must be made based on the
Reynolds number (see example process 3d and 5b).
3. Liquid – Typical Calculation Process
a. Given: D, β, ρ, CD, and input of ΔP
Calculate: 3.2.2, 3.2.11
b. Given: D, β, ρ, CD, and input of ΔP, T
Calculate: 3.2.2, 3.2.3 or 3.2.4 if req., 3.2.11
c. Given: D, β, Sl, CD, and input of ΔP, T
Calculate: 3.2.2, 3.2.3 or 3.2.4 if req., 3.2.9, 3.2.11
d. Given: D, β, μ, ρ, CD look up, and input of ΔP
Calculate: initially set CD= 0.8, 3.2.2, 3.2.3 or 3.2.4 if req., 3.2.11
Iterate until owrate is <0.01%
dierent from last calculation
4. Simplied Liquid Calculation – The simplied liquid calculation can be used if the operating
temperature is stable and the CDis constant. The simplied ow constant (k2) can be calculated
from equation 3.3.1 using the V-Cone Application Sizing sheet. The owrate can then be
calculated using equation 3.3.2. Units of measure will be the same as those listed on the V-Cone
Application Sizing sheet.
5. Gases and steam – Typical Calculation Process:
a. Given: D, β, μ, Sg, Z, k, CD, and inputs of ΔP, P, T
Calculate: 3.2.2, 3.2.3 or 3.2.4 if req., 3.2.7 or 3.2.8, 3.2.10, 3.2.11
b. Given: D, β, μ, Sg, Z, k, CD look up, and inputs of ΔP, P, T
Calculate: initially set CD=0.8, 3.2.2, 3.2.3 or 3.2.4 if req., 3.2.7 or 3.2.8, 3.2.10, 3.2.11
3.2.5 3.2.6 Look up CD3.2.11
3.2.5 3.2.6 Look up CD3.2.11 Iterate until owrate is <0.01%
dierent from last calculation
the V-Cone Flow MeasureMent systeM
Copyright © 2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
8
6. Fluid Properties – Fluid properties such as velocity, compressibility and isentropic exponent vary
with temperature and to some extent pressure. The viscosity in the calculations above could
aect the selected CDvalue, the compressibility directly eects the density and the isentropic
exponent eects the Y factor, although to a small degree. The instrumentation industry uses
many dierent approaches to calculate ow. McCrometer application engineering and the
customer must determine which uid properties are calculated at each set of ow conditions
and which properties are constant.
Application Sizing
Each V-Cone is tailored to its specic application. Before manufacturing, every V-Cone will have a
“sizing”completed according to the physical parameters of the application. The computer generated
sizing uses application data as a basis to predict the V-Cone’s performance. Full scale DP, working
ow range, expected accuracy, and predicted pressure loss are determined by the sizing process.
McCrometer has four V-Cone test lines and can calibrate meters from 1/2” to 48” with a high degree
of accuracy.
Test Lines:
Location Type Size Range Flow Range Fluid
Hemet, CA Gravimetric ½” to 3” 195 GPM Water
Hemet, CA Gravimetric 3” to 16” 3100 GPM Water
Hemet, CA Transfer Standard ½” to 2” 150 SCFM Air
Porterville, CA Volumetric 16” to 48” 40,000 GPM Water
McCrometer recommends calibration of every V-Cone
meter. Optimal accuracy is achieved when a full ow
range calibration is performed. In high Reynolds number
applications this may require an outside gas calibration. As
an alternative, McCrometer has developed a proprietary
method to accurately extrapolate ow calibration data. In
cases where the meter cannot be calibrated McCrometer can
estimate the meter Cfbased on 20 plus years of data.
All materials used for V-Cone owmeters are certied. Materials furnished to McCrometer include
a certied material test report (CMTR) from the original material manufacturer. The test reports
include material composition and applicable material grades. Upon request copies of the material
test reports can be supplied to our customers. See section 6.0 for typical materials of construction.
Wafer-Cones are available for purchase with MTRs. Requirements for MTRs must be specied at the
time of order.
McCrometer recommends a three valve or ve valve manifold
as part of a V-Cone ow measurement system. Manifolds allow
for in-line transmitter calibrations, isolation of the transmitter
from the transmission lines, without depressurizing the line,
and in-line purging of transmission lines.
the V-Cone Flow MeasureMent systeM
Copyright © 2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
9
A dierential pressure transmitter measures the dierential pressure signal from the primary
element. Once the signal is measured, the transmitter generates an electronic signal that is then
interpreted by a ow monitor or other process control system. For compressible uids, line pressure
and temperature measurements are generally required for accurate ow measurement. McCrometer
oers the following ow measurement instrumentation: dierential pressure transmitters, ow
computers, and pressure and temperature sensors for mass ow measurement.
Typical Dp Transmitters Flow
Each V-Cone meter comes with an information tag xed to the body of the tube. Below are examples
of the standard tag and the tag showing PED Certication.
InstallatIon
Copyright © 2017 McCrometer, Inc. All printed material should not be changed or altered without permission of McCrometer.
Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
10
Scope
This section provides recommendations for impulse tubing connections allowing the dierential
pressure generated by the V-Cone to be transmitted to the secondary device, normally a Dierential
Pressure Transmitter. The connection methods are designed to minimize errors in the pressure signal.
Safety
The dierential pressure signal must be transmitted in a safe manner, within piping, tubing, or
the manifold block, to the secondary device. The uid between the primary and secondary device
must be safely contained. Safe containment of the uid requires strict adherence to the applicable
standards and codes, proper materials selection, including the gaskets, and acceptable fabrication
methodology.
! When installing the impulse lines in the high and low pressure taps, NEVER
use dissimilar metals as this can cause corrosion and the rupture of the impulse line and
can cause serious injury or death.
• Any person installing, inspecting, or maintaining a McCrometer owmeter should have an under
standing of piping congurations and systems under pressure.
• The high and low pressure ports and/or optional instrumentation ports may be tted with plastic
thread protector plugs. These must be removed prior to pressurizing the system. Failure to do
so may result in serious injury.
• Before adjusting or removing any meter, be certain the system has been depressurized
completely. Never attempt to remove a meter under pressure!
• Be careful when lifting meters. Meters can cause serious injury if lifted incorrectly or dropped.
• Use only necessary and appropriate tools when working on a meter.
• Properly secure all connections before starting a system. Keep a safe and prudent distance away
from the meter during system start-up.
• Meters used in oil & gas or ammable service require a ground wire connection to arrest any
static electricity discharge.
McCrometer tests and inspects all products during manufacture and before shipment. However,
inspect the meter and accessories at the time of unpacking to detect any damage that might have
occurred during shipment. If there is a question regarding the paperwork or the owmeter, please
contact your McCrometer representative.
Orientation
A ow label is placed on each V-Cone to show the direction
of ow through the meter. For most line sizes, the centerline
of the pressure sensing taps are located 2.12” apart. The
high pressure tap is upstream. The low pressure tap is
downstream. (See Figure 15.) This information is necessary
when connecting the dierential pressure measuring device.
The pipe, tubing, or manifold installed between the
primary and secondary elements must comply with national and local standards, regulations, and
codes of practice. A process piping specication will include the specication for the isolation valve
(or block valve) closest to the primary element. The specication for the piping or tubing between
this isolation valve and the secondary device, including any additional valves, may dier from the
piping specication for the root (primary) isolation valves. The smaller size and lower temperatures in
the impulse lines often justify these dierences.
Dp
Low
Pressure
Port
H
L
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Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
11
An approved hydrostatic test or pneumatic test may be required for piping systems to prove the
integrity of the pressure containing parts of the system.
The break (change) in piping specication between the process (primary) and the instrument
(secondary) side is normally at the process isolation valve (root valve) at its secondary connection
end. If anged, then the specication break will occur at the mating face of the secondary side ange.
The recommended straight, unobstructed pipe run upstream of a V-Cone is zero to three diameters.
The recommended run downstream of a V-Cone is zero to one diameter. “Diameter”here refers to the
nominal pipe size of the pipe run.
McCrometer, along with several independent testing facilities, has tested the V-Cone in several
common piping congurations. These tests have proven the V-Cone to be within accuracy
specications even when close coupled with single 90°elbows or double 90°elbows out-of-plane.
The V-Cone can also be used in lines slightly larger than the meter tube.
In applications where the meter tube is larger than the adjacent line, such as with cement lined
piping, the user should consult the factory for additional installation requirements.
To provide best maintenance access of the impulse piping and secondary elements, it is recommended
that root block valves be installed immediately adjacent to the pressure taps of the V-Cone. If liquid
could ll the impulse lines, the root block valves should be arranged so as not to impede uid
movement and proper settling and it may be necessary to install these valves on sloping lines. When
specifying root isolation valves, practical considerations include:
a. The valve must be rated for the pipe operating pressure
b. There must be a careful choice of both valve and packing, particularly in the case of dangerous
or corrosive uids, and with gases such as oxygen
c. Valves must be chosen that do not aect the transmission of a pressure signal, particularly when
that signal is subject to any degree of uctuation.
Ball valves and gate valves are recommended for this application. Globe style block valves are not
recommended for DP transmission lines.
Valve manifolds are often installed to permit operating, calibrating and troubleshooting the
secondary device, without removing it. A typical valve manifold conguration is shown in Figure 17.
These manifolds are used:
a. To isolate the secondary device from the impulse lines
b. To open a path (bypass) between the high and low pressure sides of the secondary device. The
secondary device zero (no ow signal) can be adjusted at operating pressure with one block
valve closed and the bypass valve(s) open.
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Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
12
c. To drain or vent the secondary device and/or the impulse piping to atmosphere.
d. A 5 way manifold can be used to provide connection of the secondary device to a“dead weight”
or other reference calibrator to enable “in situ” calibration of the dierential pressure device.
Manufactured valve manifolds may reduce cost and save space by integrating the required valves
and connections into one assembly. Valve manifolds must be installed in the orientation specied
by the manufacturer to avoid possible errors caused by trapped pockets of gas or liquid in the body.
The preferred design will minimize the distance between the primary and secondary devices, while
still providing the necessary cooling for the protection of the secondary device in applications, such
as steam. The connecting piping is commonly referred to as “impulse lines”, “sensing lines”, “gauge
lines”, “instrument tubing”, “instrument piping”, or “DP piping”.
The complete design for the installation of the ow meter including the secondary elements should
consider instrument troubleshooting and calibration. Access to the impulse lines, the valves, the
valve manifold, and the secondary device will be required. Installations providing this access must
not compromise the measurement accuracy by adding excessively long impulse lines and numerous
ttings.
Longer
and more complex piping may increase uncertainties and provide more opportunities for plugging.
Plugged lines lead to loss of control and may create hazardous situations. Good design practice will
allow for natural draining of liquids and venting of gases from the impulse lines.
Any dierence in elevation between the primary device pressure taps and the secondary device will
result in a pressure dierence between the two ends of the impulse lines due to the hydrostatic
pressure of the liquid column in the impulse lines. The impulse lines shall be installed in such a way
that the hydrostatic pressure in the two impulse lines is identical. If the uids in the two lines are
not identical in density, a dierence in pressure is generated. Density dierences will arise if there
is a temperature dierence between the uids in the two impulse lines. It is recommended that, if
possible, the two impulse lines are fastened together, and if insulated, they are insulated together.
Non-identical uids in the two impulse lines can also give rise to density dierences and should be
avoided.
Pressure Taps
The pressure tap is part of the primary device. The line pressure, required for the calculation of ow
rate, is measured from the upstream pressure tap.
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Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
13
In very dirty services, pre-lled physical barrier diaphragm seals, called remote seals or chemical seals,
can be used. Deection of the diaphragm requires some additional force that must be considered in
the calibration process. For most DP meters, diaphragms add signicant uncertainty to the meter
reading.
Errors are reduced with larger diaphragms and good design. To ensure measurement sensitivity,
diaphragms are typically 3” or 4” (80 or 100 mm) in diameter. It is recommended that the impulse
lines or capillary tubes to remote seals be of identical length and be arranged to reduce exposure to
dierent temperatures
The required diameter of impulse lines depends on service conditions. The bore should not be
smaller than ¼” (6 mm) and should preferably be at least 3/8” (10 mm). The internal diameter shall
preferably not exceed 1” (25 mm). For steam applications 3/8” (10mm) to 1” (25mm) should be used.
Most instrument tubing is 316 SS but for oshore applications Duplex Steel may well be the preferred
material to avoid salt spray corrosion of the piping.
In all cases, chemical compatibility with the environment and process medium is paramount.
In most process control applications, the primary concern is reliability. If the pressure taps or the
impulse lines plug, then the DP signal is lost. This may result in a dangerous or expensive loss of
control. High reliability is required for ow signals used in process safety management. A minimum
I.D. of 5/8” (16 mm) is recommended in industrial applications. Some users even specify ¾” (18 mm)
as the minimum I.D. For high temperatures in condensing vapor service, 1” (25 mm) is specied to
allow for unimpeded ow of condensate. In small piping and with clean uids, appropriate smaller
sizes may be used. In all congurations, it is recommended that stainless steel impulse lines are used.
Steam temperatures could be as high as 1500oF (815 o C), which is much higher than can be tolerated
by a standard DP transmitter. The standard dierential pressure transducer can only tolerate a
temperature of approximately 200oF (93o C).To isolate the transducer from the very high temperatures
the common techniques are to install a condensate pot in the line or to have a suciently long DP leg
to allow for sensing leg cooling prior to the transmitter. In all congurations, it is recommended that
stainless steel impulse lines are used.
o o
o
o
Some hot or very cold lines require thermal insulation for personnel protection. It may also be
necessary to insulate and“heat trace”the impulse lines to avoid freezing or unintended condensation.
The amount of heat used must avoid the undesired vaporizing of liquids in liquid lled lines, or
the prevention of condensation with condensable vapors. Bundling the impulse lines together so
that the impulse lines will be at approximately the same temperature is preferred. Having the DP
transmitter in a temperature controlled Instrument Housing is good practice for accurate metering in
an environment exposed to large temperature variations such as an oshore platform or a desert site.
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Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
14
The pressure taps on the primary device shall be between the horizontal centerline and the top of
the pipe (3 o’clock to 12 o’clock or 9 o’clock to 12 o’clock) unless the measured uid is a vapor which
is intended to condense in the secondary system (see section 4.19). However, if the uid is a “wet
gas”, i.e. a gas containing small quantities of liquids, the taps should be vertical if possible to allow
the liquids to drain away from the secondary device. The connecting lines from the primary device
to the secondary device shall slope upwards for gases. The recommended slope for self-draining is a
minimum of 30°.
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Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
15
The pressure taps shall be between horizontal centerline and 60obelow centerline (3 o’clock to 5
o’clock or 7 o’clock to 9 o’clock). Taps at bottom dead-center may accumulate solids if they are present
in the liquid; taps above the centerline will accumulate air or non-condensing gases. In neither case
should the taps be more than 60° to the horizontal plane.
This is the most dicult application for DP piping and requires careful consideration during
installation. Steam can be at a very high temperature which can damage the transmitter; in addition,
it can be in the liquid or gaseous phase depending on temperature and pressure. As such, the DP
pipework must be oriented in such a manner that it can operate with a gas or liquid present.
The pressure taps shall be on the horizontal centerline (3 o’clock or 9 o’clock ) of the primary device. In
condensing hot vapor service, such as steam, the uid in the impulse lines is liquid condensed from
the vapor. In this case the pressure taps should be horizontal with the impulse lines oriented to the
DP transmitter, in accordance with Figure 20.
There is a concern that at start-up the secondary device could become exposed to the vapor
temperature before the lines ll with condensed liquid and cool. In this case it is prudent to have a
plugged Tee tting in the impulse line to enable the impulse line and secondary device to be lled
with liquid (water for steam service) prior to start up (see Figure 20).
Cryogenic (very low temperature) systems may require special designs not considered here. The
liquids in the lines will isolate the secondary device from the temperatures of the primary owing
uid. The temperature dierence may be considerable over a short distance of 100 mm (4”) to 200
mm (8”).
18”
The
recommended
distance between the
meter and transmitter
is 18 inches.
18”
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Any published technical data and instructions are subject to change without notice. Contact your McCrometer representative
for current technical data and instructions.
16
In the case of vertical pipes there are generally no problems regarding the radial position of pressure
taps. With the V-Cone care must be taken in the piping arrangement for vertical up ow and for
vertical down ow. In this section vertical down ow and vertical up ow will be separated.
In this orientation extreme care must be exercised to ensure that no trap forms in the downstream
tap, such that no gas is trapped in a liquid, or that no liquid is trapped in a gas. In applications where
there is dirt or moisture, such as with steam, it is necessary to install wall taps on a V-Cone Meter in
vertical up ow.
In clean dry non-condensing gases, where it is guaranteed that no liquid or dirt can ll the cone,
standard taps can be used. The position of the transmitter is not critical. The transmission lines can
be run straight out to the transmitter or horizontal and then up or down to the transmitter.
InstallatIon
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for current technical data and instructions.
17
In most process applications the assumption should be made that there can be gas or vapor
associated with a liquid even if the liquid is water. Consequently the piping must permit gas to rise
back into the owing medium. The DP piping should be brought out horizontally for as short a
distance as possible and then down to the transmitter and the transmitter should be below both taps.
Note: wall taps must be used for dirty liquids. Standard taps should only be used on clean liquids.
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