© Cameron Measurement Systems 5th

April 2010

D.P. Cone Flow Meter Technology

“New Ideas”

PHILIP A LAWRENCE

DIRECTOR OF BUSINESS DEVELOPMENT

CAMERON’S MEASUREMENT SYSTEMS

HOUSTON TEXAS USA.

Abstract

The cone meter has become synonymous with specialist metering applications over many years due to

special traits that are inherent in this type of meter design. The original cone meter concept was taken

from the “Venturi” original design in 1791 by Hershel and other variants like Burton Dunlingson’s Inverse

Venturi (Patented in 1935).

Cone meters have been used on many fluids such as Steam, Wet Gas , Liquids that have trash,

asphaltenes and wax in pipes together with applications that have installation issues such as short

meter runs lengths (usually off-shore) like test separators. They have been used for some limited custody

transfer applications with user-party agreements and have been quite successful through the years in

other industrial applications such as water measurement.

History

The original inventor of the meter, Mr. Floyd McCall of Hemet California conceived the original design in

the form of a flow conditioning device / static mixer or fluid dispersing devices and also in the form of a

differential pressure flow meter in the early 90’s with a patent being issued in 1986 European Patent

No. 0 277 121 which expired in August 2006,and a US based patent issued in 1985 USA patent

numbers 4638,672.. 4812,049 now expired.

This original design of cone meter was patented with up and down-stream cone angles that were steeper

than subsequent manufactured models. Cones for the meter are usually made from solid bar stock or

fabricated sheets formed to the required shape.

There have been many successful research papers on the cone meter and new design and test work

done by various companies are making the cone meter more accepted into the market place.

Main focus of the paper

This paper focuses on the design of the cone meter differential producer element rather than its

application since the original cone meter invention was patented based on a concept of a centrally

mounted cone shape with an upstream wall tap, and a low pressure tap in the middle of the cone with a

mechanism to allow the low (downstream) pressure to be read at the pipe wall.

Since the original patented design variants of the device have been manufactured with wall taps across

the beta edge, also various different cone securing methods have been tried and used as well. The

following designs and concepts have been implemented with some great success.

© Cameron Measurement Systems 5th

April 2010

Cone Meter Design Variants

The writer has seen from over 28 years in the industry the need to have flexibility in a flow meter element

whether this was for a turbine meters, cone meters or any device that operated in an environment where

the process conditions changed over time resulting in a required change in diameter of pipe-work and

other supporting structures. This can be costly and time consuming so various concepts have

materialized to facilitate a fix!

The following designs and variants are commercially available and used for cone meter technology and

satisfy various needs relating to changing process conditions with time.

Existing and Generic Design.

The following drawing fig 1.0 below shows the original variant of a cone meter fixed beta ratio.

Fig 1.0

Variant 1

This design uses wall taps and is usually implemented when a cone type meter is installed vertically in a

pipe. (Fig2.0)

Fig 2.0

© Cameron Measurement Systems 5th

April 2010

Variant 2

A New concept for this is to make the meter as a removable cartridge so that that is manufactured with a

sleeve assembly and vanes to help with flow conditioning in extreme disturbance conditions as per Fig

3.0 below.

Fig 3.0

Variant 3

This assembly uses removable sections that change the effective area ratio by using a or area ratio

changer (ARC ©) Figure 4.0. Currently a Y factor (expansibility) equation has not been published for this

device variant and flow calibration is also still required to determine its Cd, as with other devices.

Fig 4.0

Beta or Area Ratio

Changer

© Cameron Measurement Systems 5th

April 2010

Variant 4- Bi-directional flow

This type of assembly uses 2 meters back to back of any variation to enable forward and reverse flow,

this concept has been used very successfully to measure natural gas in a bi directional stream Fig 5.0

and an integral bi directional system built into a housing shown in Fig 6.0.

Fig 5.0

Fig 6.0

Cone meter area ratio’s (’s) are varied to accommodate the measurement of different flow rates by

changing the cone length and thus the cone diameter (Fig 7.0).

This changes the effective diameter of the cone in relation to the pipe diameter and thus the beta or

effective area ratio and ultimately the velocity across the Beta Edge.

Commercially made cone meters operate generally in ratios from 0.45 - 0.85. It must be noted that as

the beta ratio becomes larger (approaching 0.8 - a smaller cone diameter) the meter performance

changes and the measurement uncertainty can become larger where disturbed flow profiles are evident.

This “performance” effect is caused by the reduced interaction between the cone area and the fluid, i.e. a

smaller cone does less work on the fluid so the flow linearization aspect of the meter is reduced.

© Cameron Measurement Systems 5th

April 2010

Care must be taken when using smaller cones where valves or other flow disturbance generators are in

line and upstream of differential pressure cone device. The cone meter manufacturer should be able to

advise of the minimum straight lengths per beta ratio and diameter versus Reynolds Number per

Diameter (ReD) regarding this effect.

The mass flow rate equation for Generic D.P. Cone Meters is exactly the same as per any standard DP

device (Orifice, Venturi meters) with the exception of the Cd implementation which is usually derived from

laboratory testing by the manufacturer or other independent labs and not generally by mathematical

correlation.

The beta ratio determination as shown in the Appendix are slightly different than for the other standard

DP devices due to the external annulus being used to determine beta ratio.

The fundamental (universal) DP equations for a cone meter are also shown in Appendix #1.

Fig -7.0

Usage in a Bi-directional Flow Regime.

The use of differential pressure type meters to measure accurately a bi-directional gas flow in a

pipeline can have major measurement uncertainty issues due to the geometric difference in the

differential producer element shape when used in the reverse direction

Meter discharge coefficient’s may be different in these particular cases for geometric devices such as

concentric, square edged and flange tapped orifice flow meters and venturi meters.

Current national and international measurement standards state that bi-directional flow measurement is

not permitted using orifice plate type flow meters for a “good measurement uncertainty” and that meter

runs dedicated for each direction must be used in this application.

Beta Edge

Taps: Static LowP

© Cameron Measurement Systems 5th

April 2010

Cone Meter Installation and Data Recording

The cone meters where installed fitted with a Scanner 2000 type flow computer which is designed to

read static pressure , differential pressure, and temperature and also perform integral liquid hydrocarbon

flow calculations based on API algorithms, schematic as seen in Fig 8.0 below can be set to calculate

Fig - 8.0

Corrected volume and mass flow depending on the configuration being used also wet-gas and steam

metering are a possibility with this type of combination.

Appendix #1

© Cameron Measurement Systems 5th

April 2010

References.

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(18)Lawrence Wellhead Metering by V- Cone Technology NSFMW 2000 Gleneagles, Scotland,UK(19) Braid C Cameron Inc (Canada) Cone Equations for Flow Computers a Technical Document

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March 2009 – Malaysia.(24)NEL South Asia Flow Measurement Workshop Malaysia March 2010 –Lawrence ; Challenges

Using Differential Pressure Cone Meters In Heavy Oil Measurement.