Badger Meter Preso Gemini Cone User manual

Dierential Pressure Flow Meter
Gemini Cone
DPM-UM-00206-EN-03 (June 2018) User Manual

Dierential Pressure Flow Meter, Gemini Cone
Page ii June 2018DPM-UM-00206-EN-03

CONTENTS
Scope of This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Terminology and Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Unpacking and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Meter Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Valve Manifolds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Shuto Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Dierential Pressure Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Meter Nameplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Straight Pipe Run Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Installation Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Installation Checkpoints for the Transmitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Mounting Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Meter Orientation and Transmitter Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Pressure Tap Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Line Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Dierential Pressure Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Transmitter Connection Tubing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Full Port Block Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Impulse Tubing Size Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Impulse Tubing Length and Conguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Meter Installation for Liquid Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Installation Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Horizontal Meter Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Bubble Pot Installation (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Vertical Meter Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
User Manual
Page iiiJune 2018 DPM-UM-00206-EN-03

Transmitter Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Meter Installation for Gas Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Installation Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Horizontal Meter Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Condensate Chamber (Drip Pot) (Optional for Wet Gas) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Vertical Meter Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Transmitter Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Meter Installation for Steam Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Installation Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Horizontal Meter Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Vertical Meter Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Transmitter Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
System Modications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Square Root Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Gauge Line Error . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Elevation and Temperature Eects in Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Specications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Part Number Construction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Wafer Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Threaded and Socket Weld Mount. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Flanged Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Butt Weld Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Dierential Pressure Flow Meter, Gemini Cone
Page iv June 2018DPM-UM-00206-EN-03

SCOPE OF THIS MANUAL
This manual contains instructions for installing and operating the Preso® Gemini Cone Differential Pressure Flow Meter.
MPORTANTI
Read this manual carefully before attempting any installation or operation. Keep the manual accessible for future reference.
SAFETY
Terminology and Symbols
Indicates a hazardous situation, which, if not avoided, is estimated to be capable of causing death or serious
personal injury.
Indicates a hazardous situation, which, if not avoided, could result in severe personal injury or death.
Indicates a hazardous situation, which, if not avoided, is estimated to be capable of causing minor or moderate
personal injury or damage to property.
Considerations
WARNING
NEVER OPEN A MANIFOLD VALVE OR FLANGE UNLESS YOU HAVE FIRST VERIFIED THAT THE SYSTEM IS COMPLETELY
DEPRESSURIZED. DURING LIQUID OR WET GAS SERVICE, OPEN VALVES VERY SLOWLY TO AVOID SLUGGING IN THE
METER RUN.
WARNING
SECURE ALL CONNECTIONS PROPERLY BEFORE STARTING UP A SYSTEM. KEEP A SAFE DISTANCE AWAY FROM THE
PROCESS UPON STARTUP.
WARNING
BE MINDFUL OF STATIC ELECTRICITY GENERATED BY INSULATED FOOTWEAR ETC., AND ALWAYS GROUND YOURSELF
BEFORE TOUCHING PIPES IN THE HAZARDOUS AREA WHERE FLAMMABLE GAS IS BEING METERED OR MAY BE PRESENT.
UNPACKING AND INSPECTION
Upon opening the shipping container, visually inspect the product and applicable accessories for any physical damage such
as scratches, loose or broken parts, or any other sign of damage that may have occurred during shipment.
OTE:N If damage is found, request an inspection by the carrier’s agent within 48 hours of delivery and file a claim with the
carrier. A claim for equipment damage in transit is the sole responsibility of the purchaser.
WARNING
ALWAYS USE PROPER PROCEDURES AND EQUIPMENT FOR LIFTING AND MOVING THE GEMINI CONE METER TO AVOID
RISK OF INJURY.
Scope of This Manual
Page 5June 2018 DPM-UM-00206-EN-03

INTRODUCTION
The Preso Gemini Cone meter is a differential pressure device that combines excellent performance with many benefits
including low maintenance, low head loss and a unique ability to have none/minimum straight pipe runs in front of the
meter. The Gemini Cone meter produces a pressure differential across a pair of pressure measurement ports. The movement
of a fluid around the cone-shaped element creates a pressure differential between an upstream and a downstream pressure
port, which is processed by a differential pressure transmitter to provide the flow rate. The conical shape of the element also
causes the flow meter to act as a flow straightener, pre-conditioning the flow and making the Gemini Cone meter a versatile
measuring instrument for many applications. Badger Meter takes pride in designing an optimized differential pressure
metering solution for your system.
Theory of Operation
The Preso Gemini Cone meter creates a differential pressure that is proportional to the rate fluid flow. A transmitter measures
the differential pressure and outputs an integrated electronic signal, typically via Modbus or a 4…20 mA output, to a flow
computer or other process controller for interpretation and readout. For compressible fluids, line pressure and temperature
measurements are required for accurate flow rate calculations as well as compensation for the adiabatic change in the
expansion factor. As fluid flowing through the pipe flows around the cone, a pressure drop occurs. The static line pressure (P1)
is measured via a wall tap located just upstream of the cone. Pressure is also measured via a sensing tap that is connected to
the cone and measures pressure at a point immediately downstream of the cone (P2). The fluid flow rate is calculated from the
difference between the two pressures using variations of the Bernoulli flow principles and equations.
∆P
High Pressure
Port (P1)
Low Pressure
Port (P2)
Support and Cone
Assembly
Meter Body
Flow
Figure 1: Principles of operation
Applications
The Gemini Cone meter is designed to work in unprocessed and processed applications, and is ideal for applications that
present a wide range of measurement challenges. The Gemini Cone meter is a great solution for steam and boilers, coke oven
gas, multiphase (non-homogeneous) fluids, biogas and industrial gas management.
Introduction
Page 6 June 2018DPM-UM-00206-EN-03

Meter Components
The meter comprises three primary elements, as shown in Figure 1 on page 6:
• A meter body or tube with various available end connections.
• A cone assembly, either fabricated or machined from a solid piece of metal, positioned in the center of the meter tube.
• A pair of pressure taps—a wall tap upstream and an integral sensing tap downstream—for reading the differential
pressure across the center of the meter tube. (Alternately a downstream tap may be used under certain process
measurement conditions.)
The meter can be manufactured from various materials (carbon and stainless steels are standard, but more exotic materials
such as duplex stainless steel or nickel-based alloys are also available upon request) to meet the specific requirements for
metering steam, air, natural gas, digester gas, nitrogen, ethanol, and a host of media from crude oil to industrial gases.
Preso Gemini Cone meters are differential pressure flow devices providing highly accurate and repeatable measurements of
liquids, gases and steam. The meter design provides longer lasting accuracy and lower permanent pressure loss than orifice
type meters, reducing maintenance and operating costs. The Gemini Cone can be built to meet the highest pressure and
temperature specifications often limited in other flow meter technologies. All models can also be supplied with RTD's and
transmitters to provide an economical mass flow measurement solution.
System Components
Valve Manifolds
A 3-way or 5-way valve manifold isolates the transmitter from the process lines. A manifold allows the operator to calibrate
the transmitter without removing it from the impulse tubing, draining the transmitter and impulse tubing or venting it to
atmosphere. Valve manifolds must be oriented according to the manufacturer’s instructions to prevent trapping air or liquid.
Shutoff Valves
Choose a blocking valve that is rated for the operating pressure of the pipe in which it will be installed. Where dangerous or
corrosive fluids or gases like oxygen are likely, the blocking valve and packing must provide ample protection. The valves
must not affect the transmission of the differential pressure signal.
Install blocking valves next to the Gemini Cone meter pressure taps.
Differential Pressure Transmitter
A differential pressure transmitter interprets the differential pressures generated by the cone within the meter body and
provides an analog or serial output to a flow computer or data control system. Select a transmitter that is rated for accuracy
and safety for your particular operating conditions.
Differential pressure devices must be zeroed following installation. The procedure varies somewhat for liquid, gas, and steam
applications and by manufacturer. See the manufacturer’s literature for complete procedures on zeroing the transmitter.
Meter Nameplate
This name plate identifies the proper specifications associated with the meter designed for the defined application. The
direction of the flow is also indicated on each tag.
Figure 2: Nameplate
Introduction
Page 7June 2018 DPM-UM-00206-EN-03

STRAIGHT PIPE RUN REQUIREMENTS
With most flow elements, proper operation and performance is dependent on the required lengths of unrestricted upstream
and downstream piping. One of the advantages of the Gemini Cone meter is that a fully developed symmetrical flow profile
is achieved with relatively short upstream and downstream lengths, so it needs minimal if any upstream and downstream
straight pipe runs. We recommend that the Gemini Cone meter be installed with zero to five pipe diameters and zero to three
pipe diameters downstream.
0.4 0.5 0.6 0.7 0.8
Flow
BA
Single Elbow
A00011
B00011
Flow
BA
Two Elbows In-Plane
A00011
B00011
Flow
BA
Two Plane
Changes
Two Elbows Out of Plane
A00011
B00011
1½ - 3 D
Flow
AB
≤ 2D
Pipe Reduction
A11122
B1 1 1 2 2
1 - 2 D
Flow
AB
≥ ½ D
Pipe Enlargement
A11122
B11122
D A B
Flow
Pipe With Tee
A00011
B00011
A B
Flow
Gate/Globe Valve Fully Open/Partially Open
A33344
B00011
A33344
B33344
Straight Pipe Run Requirements
Page 8 June 2018DPM-UM-00206-EN-03

INSTALLATION
Installation Basics
Here are the basic steps for installing a Gemini Cone meter system:
1. Install the meter in the meter run in accordance with the ow run requirements. See “Straight Pipe Run Requirements” on
page8.
2. Secure the manifold to the meter taps.
3. Connect the differential pressure transmitter to the manifold, following the guidelines in “Mounting Location” on
page10.
4. Connect the transmitter to the flow computer according to instructions in the transmitter user manual.
5. Zero the transmitter.
NEVER USE EXCESSIVE PRESSURE OR FORCE WHEN CONNECTING TUBING TO A DIFFERENTIAL PRESSURE
TRANSMITTER.
IF HIGH-TEMPERATURE FLUIDS ARE LIKELY TO BE ENCOUNTERED, MAKE SURE THE CONNECTION TUBING IS RATED FOR
THE ANTICIPATED TEMPERATURE RANGE.
Installation Checkpoints for the Transmitter
Before putting the Gemini Cone meter into service, verify that the transmitter is installed properly by reviewing the
following checkpoints:
• Is the transmitter full scale correct?
• Has the transmitter zero been checked and/or adjusted?
• Are the transmitter and flow computer set to the appropriate modes—linear or square root?
• Have the transmission lines to the transmitter been purged?
• Are there any leaks in the transmission lines?
• Is the manifold bypass valve closed?
• Is the Gemini Cone meter's high pressure port located upstream of the low pressure port?
Installation
Page 9June 2018 DPM-UM-00206-EN-03

Mounting Location
The Gemini Cone meter should be installed with zero to five pipe diameters of straight run upstream of the meter and zero
to three pipe diameters downstream (see “Straight Pipe Run Requirements” on page8). The meter can be used in pipelines
that are slightly larger than the meter tube; however, if the meter tube is larger than the pipeline, operators should contact
Badger Meter or installation requirements. This is usually determined before supply according to application and the degree
of accuracy and performance required.
Meter Orientation and Transmitter Position
The location of the transmitter with respect to the meter should be based on the properties of the fluid being measured and
the direction of flow through the pipeline. The direction of flow is clearly labeled on the body of every Gemini Cone meter.
The meter must be installed so that the high pressure tap (labeled P1 in Figure 1 on page 6) is always upstream of the low
pressure tap labeled P2.
Vertical installations measuring liquids may introduce a slight hydrostatic head effect, which must be considered when
zeroing a transmitter. With liquid applications, the meter should be installed so flow is moving UP to ensure a full pipe. Use
of a 3-valve manifold for zeroing a transmitter. Before installation of any Gemini Cone meter, inspect the meter for damage,
particularly at the sealing surfaces. Any damage should be reported to Badger Meter as soon as possible. Each flow element
has an arrow indicating the required direction of flow. Failure to properly orient the meter according to the direction of flow
will cause improper results and potentially damage the meter.
For vertical installations, the location of differential pressure taps is unrestricted, as long as the static pressure tap is upstream
of the lower-pressure tap.
WARNING
NEVER EXCEED THE MAXIMUM PRESSURE OR TEMPERATURE RECOMMENDED FOR THE MEASURED PROCESS.
EXCEEDING PROPER PRESSURE OR TEMPERATURE RATINGS CAN LEAD TO PERSONAL INJURY OR EQUIPMENT
DAMAGE. THE PROCESS PIPING FLANGES SHOULD BE IDENTICAL TO THOSE ON THE GEMINI CONE BOTH IN PRESSURE
CLASS AND INSIDE DIAMETER. THE PROCESS TEMPERATURE AND PRESSURE SHOULD NEVER EXCEED THOSE FOR
WHICH THE ELEMENT HAS BEEN DESIGNED.
IF HIGH-TEMPERATURE FLUIDS ARE LIKELY TO BE ENCOUNTERED, MAKE SURE THE CONNECTION FITTINGS VALVES
AND TUBING ARE RATED FOR THE ANTICIPATED TEMPERATURE RANGE.
Pressure Tap Location
Location of the pressure taps will vary with the product flowing through the pipeline (liquid, gas, or steam) and the
orientation of the meter (vertical or horizontal).
For horizontal installations, the following installation guidelines apply:
• For measuring liquid, differential pressure taps should be located in the bottom half of the pipeline, between 4 o’clock and
5 o’clock positions, or between 7 o’clock and 8 o’clock positions.
• For measuring gas, differential pressure taps should be located in the top half of the pipeline. For wet gas, taps should be
located between the 10 o’clock and 2 o’clock positions to allow proper drainage of condensate.
• For steam, differential pressure taps should be located in the side of the pipeline at 3 o’clock or 9 o’clock.
Liquid
120…150° or −120…−150°
Wet Gases
60… −60°
Dry Gases
90… −90°
Steam
90…−90° Only
0° 0° 0° 0°
Figure 3: Typical piping configurations for liquid, gas, and steam
Straight Pipe Run Requirements
Page 10 June 2018DPM-UM-00206-EN-03

Line Installation
All flanged Gemini Cone meters require a gasket between the flange on the process line and the mating flange on the
meter itself. Select gaskets that match the pressure and temperature ratings of the Gemini Cone flanges and resist corrosive
properties of the process fluid.
Before completing the bolting process, make sure that the gaskets are properly centered so that protrusion into the pipe
opening is minimized. Misalignment may cause added flow turbulence which can affect meter performance, although
such effects are typically minimal (depending upon the application). Bolt the element in line with suitable hardware using
recommended bolt torques for the type and class rating of the flanges.
TORQUE ALL MODELS PER ANSI FLANGE RATINGS.
DO NOT EXCEED SPECIFIED TORQUE.
OTE:N Tighten the flange bolts in a progressive star pattern to avoid localized stress on the gaskets.
Dierential Pressure Connections
The high pressure connection is always on the upstream side of the flow direction arrow and the low pressure connection on
the downstream side. Fittings used must be able to withstand the process temperature and pressure conditions, as well as
provide proper corrosion resistance. See the appropriate secondary instrument instructions for connections to the secondary
instrument high and low ports. Coat all fitting threads with a process compliant thread sealant prior to tightening. Once
tightened, torque mark all fittings for future reference.
Transmitter Connection Tubing
Before connecting the Gemini Cone meter to the transmitter, consider the following tips for optimizing your system’s
measurement accuracy. In a well-designed installation, fluids will drain freely from the process lines and gases will vent to
the atmosphere.
Full Port Block Valves
Adding block valves to the pressure taps of the meter will simplify any type of calibration or maintenance to any upstream
components. Select valves that are compatible to the pressures, temperatures and system media.
Impulse Tubing Size Selection
Transmitter connection tubing, the tubing that connects the Gemini Cone meter taps to the transmitter, can vary in
diameter for different applications. A minimum diameter of 3/8 inch (10 mm) for the internal diameter (ID) of the tubing is
recommended, and as a general rule it should be no smaller than 1/4 inch (6 mm). The tubing ID must not exceed 1 inch
(25 mm) at the maximum.
In most applications, the primary concern is measurement reliability. If the pressure taps or the connecting tubes become
plugged, the reliability of the flow measurement is lost creating a safety risk. High reliability is required for any flow signals
used to manage safety processes. A minimum tubing ID of 5/8 inch (16 mm) is recommended in industrial applications.
For steam applications, the ID should be 3/8… 1 in. (10…25 mm).
Straight Pipe Run Requirements
Page 11June 2018 DPM-UM-00206-EN-03

Impulse Tubing Length and Configuration
Impulse tubing is used to connect the sensing taps of the cone meter to the manifold connected to the differential pressure
transmitter. One section of tubing should connect the high-pressure tap to the high-pressure side of the differential pressure
transmitter; another section of tubing should connect the low-pressure tap to the low-pressure side of the differential
pressure transmitter.
• Impulse tubing should be installed with a gradient of 1:12 at a minimum to help prevent undesirable fluids from being
transferred to the differential pressure transmitter.
• If tubing is installed in a horizontal orientation, install a gas/liquid separator device.
• Avoid abrupt bends in impulse tubing.
• If impulse tubing sections are long, use mounting brackets to support them.
• Tubing length must be short enough for a high degree of accuracy, and long enough for proper cooling of
high-temperature fluids before they reach the transmitter.
• Make sure the installation permits access to the connection tubes, valves, valve manifolds and transmitters
for maintenance.
• Limit the number of fittings and avoid long tubing sections that can impair measurement accuracy and increase the risk
of plugging.
• Avoid changes in tubing elevation. Differences in elevation will cause a difference in the hydrostatic pressure of the liquid
column in the process lines, which can result in inaccurate differential pressure measurements. Fasten the process lines
together, if possible, to keep their relative elevations consistent.
• Install process lines so that they slope in only one direction (up or down). If piping must slope in more than one direction,
do not allow more than one bend. Install a liquid or gas trap at the lowest point in a gas service installation. Install gas trap
at the highest point in a liquid service installation.
Straight Pipe Run Requirements
Page 12 June 2018DPM-UM-00206-EN-03

METER INSTALLATION FOR LIQUID SERVICE
Installation Options
• Meter Orientation—Gemini Cone meters can be installed in a horizontal or vertical position. Horizontal is the standard
orientation, however where space is very limited, a vertical position may prove to be the best option.
• Pipe Orientation—The orientation of piping is dictated by the position of the meter, the type of product being measured,
and for vertical meter installations, the direction of flow. When a vertical piping system is used, the operator must give
special consideration to the piping configuration to prevent gas from being trapped in liquid differential pressure lines.
Horizontal Meter Installation
For horizontal installations, pressure taps must be positioned 30…60° below the horizontal centerline (4…5 o'clock or
7…8 o'clock). Taps at the bottom of the pipe may become plugged with solids from the liquid; taps above the centerline can
accumulate air or non-condensing gases. In liquid service, the connecting lines from the meter shall slope downward to the
transmitter with no upturns or pockets. The minimum recommended slope for self-venting is 1:12.
Bubble Pot Installation (Optional)
In liquid applications where the transmitter must be mounted above the metering line, gas or vapor in the liquid can collect
at the highest point in the instrument tubing and give a false differential pressure reading. Bubble pots may be the only
effective solution for such installations. The piping from the meter connects to the bubble pot anywhere between the 10
o’clock and 2 o’clock positions on a horizontal plane.
3-Valve Manifold
DP Transmitter
or
Direct Read Gage
Side View
HI LO
HI LO
Flow
Top View
Flow
Front View
Notes:
1. ø = 1 in/ft (80 mm/m) for water; 2…4 in/ft (160…320 mm/m) for more viscous uids.
2. Minimize all lead line lengths.
Up to –45°
ø
ø
Figure 4: Typical horizontal installation for liquids
Meter Installation for Liquid Service
Page 13June 2018 DPM-UM-00206-EN-03

Vertical Meter Installation
In most process applications, some level of gas or vapor exists in a liquid service, even if the liquid is water. As a result, the
piping configuration must be designed so gas can rise back into the flow stream. The process piping should be extended
horizontally a very short distance from the downstream tap and then sloped at a nominal 1:12 angle to the top of the
manifold block. Mount the manifold block horizontally below the upstream tap so that piping from the upstream tap to the
manifold slopes downward also.
WHEN THE PROCESS IS TURNED OFF, PARTICULATES MAY SETTLE IN THE LOW-PRESSURE PORT. FLUSH THE
LOW-PRESSURE PORT WITH AN INERT FLUID BEFORE STARTING THE METER.
OTE:N Do not use downward flow piping configurations that use the standard upstream and downstream pressure ports for
liquid applications due to the risk of trapping gas.
Transmitter Calibration
Calibrate transmitters (differential pressure and/or multi-variable) according to the manufacturer’s recommendations,
appropriate national or company standards and contractually agreed methodology. Consider the process conditions in which
the Gemini Cone meter and transmitter are installed and operated.
HI
LO
Flow
HI
LO
Flow
DP Transmitter
or
Direct Read Gage
Side View
DP Transmitter
or
Direct Read Gage
Front View
3-Valve Manifold
3-Valve Manifold
Figure 5: Typical vertical installation for liquids
Meter Installation for Liquid Service
Page 14 June 2018DPM-UM-00206-EN-03

METER INSTALLATION FOR GAS SERVICE
Installation Options
• Meter Orientation—Gemini Cone meters can be installed in a horizontal or vertical position. Horizontal is the standard
orientation, however where space is very limited, a vertical position may be the best option.
• Connection Tube Orientation—The orientation of connection tubing is dictated by the position of the meter, the type
of product being measured and, for vertical meter installations, the direction of flow. When a vertically oriented metering
system is used, give special consideration to the tubing configuration to prevent liquid being trapped in gas differential
pressure lines.
Horizontal Meter Installation
The pressure taps on the Gemini Cone meter should be between the horizontal centerline and the top of the pipe
(3…12 o'clock or 9…12 o'clock). If the fluid is a wet gas (that is, a gas containing small quantities of liquids or condensate),
situate the pressure taps in a vertical position (12 o’clock) to allow all liquids to drain away from the transmitter. If the
connecting tubing extending from the cone meter to the transmitter is not installed in a vertical position, it should slope
upward (at least 1:12) for proper drainage.
Flow
HI LO
Flow
Side View
3-Valve Manifold
DP Transmitter
or
Direct Read Gage
Top View
3-Valve Manifold
DP Transmitter
or
Direct Read Gage
HI LO
Φ
HI LO
Notes:
1. ø = 1 in/ft (80 mm/m)
2. Minimize all lead line lengths.
Figure 6: Typical horizontal installation for gases
Condensate Chamber (Drip Pot) (Optional for Wet Gas)
The condensate chamber is a collection vessel that helps prevent liquid pockets from collecting in gas instrument tubing.
If drip pots are used, they should ideally be mounted immediately following the shutoff valves installed near the upstream
and downstream pressure taps of the meter. For wet gas applications, the piping from the meter connects to the condensate
chamber in a 3 o'clock or 9 o'clock position on a horizontal plane. The chambers are positioned vertically so that the meter
connection and instrument connection points are at the top and drain points are at the bottom of the chambers.
Meter Installation for Gas Service
Page 15June 2018 DPM-UM-00206-EN-03

Vertical Meter Installation
When installing the meter in a vertical position, make sure that no trap forms in the downstream tap such that gas is trapped
in a liquid or liquid is trapped in a gas.
When measuring dry, non-condensing gases, where there is absolutely no risk for liquid being present, extend the piping
from the downstream pressure tap of the cone meter horizontally and then angle it upward to connect to the manifold block.
Mount the manifold block horizontally. Slope the tubing from the upstream tap of the cone meter 1 in./ft to the same level as
the downstream tap piping to connect to the manifold (see Figure 7).
IF THERE IS ANY LIQUID PRESENT IN THE GAS, DO NOT USE THE PIPING ARRANGEMENT SHOWN IN Figure 7. THE "U”
CONFIGURATION COULD TRAP LIQUID IN THE CONE, CHANGING THE DOWNSTREAM PRESSURE.
Transmitter Calibration
Calibrate transmitters (differential pressure and/or multi-variable) according to the manufacturer’s recommendations,
appropriate national or company standards and contractually agreed methodology. Consider the process conditions in which
the Gemini Cone meter and transmitter are installed and operated.
Front View Side View
3-Valve Manifold
DP Transmitter
or
Direct Read Gage
HI
LO
Flow
3-Valve Manifold
HI
LO
Flow
DP Transmitter
or
Direct Read Gage
Figure 7: Typical vertical installation for gases
Meter Installation for Gas Service
Page 16 June 2018DPM-UM-00206-EN-03

METER INSTALLATION FOR STEAM SERVICE
Steam measurement is one of the most difficult applications for differential pressure transmitter tubing and requires careful
consideration during installation. Steam is usually at a high temperature, which will damage the transmitter. In addition,
steam can vary between liquid or gaseous phase depending on temperature and pressure. Due to this, the differential
pressure impulse tubing must be oriented in such a manner that it can operate with gas liquid, or a combination of the
two present.
Installation Options
• Meter Orientation—Gemini Cone meters can be installed in a horizontal or vertical position. Horizontal is the standard
orientation, however where space is very limited, a vertical position may prove to be the best option.
• Connection Tubing Orientation—The orientation of the impulse tubing is dictated by the orientation of the meter, the
type quality of the steam being measured, and for vertical meter installations, the direction of flow. When a vertical meter
run is used, the operator must give special consideration to the impulse tubing configuration to prevent liquid from being
trapped in gas differential pressure lines.
• Condensate Chamber—The condensate chamber is a liquid reservoir that helps prevent steam from entering the
differential pressure transmitter. In most cases, a large-diameter tee is all that is required to collect the liquid. However, if
the DP measuring instrument is designed with hydraulic/pneumatic bellows (such a Barton 202E chart recorder), a larger
volume condensate chamber will be required. Modern DP transmitters have very little diaphragm movement and do not
require the large-volume condensate chamber.
Horizontal Meter Installation
Install the pressure taps above the horizontal centerline (9…3 o'clock) of the primary device. In condensing hot vapor service
such as steam, the fluid in the impulse lines is liquid that has been condensed from the vapor. The use of a condensate
chamber is mandatory to prevent hot process fluid from damaging the transmitter. Slope the impulse tubing upwards from
the cone meter to the condensate pots. A condensate pot can be a tubing tee (for low volume DP instruments) or a full-size
condensate chamber (for high volume DP instruments). In either case, install the condensate pots at exactly the same level to
ensure accurate differential pressure readings. Fill the line from the bottom of the tee to the transmitter mounted below the
tee to the point where excess fluid can drain back into the meter.
In many cases, water (steam condensate) is used for the fluid fill. However, in cold weather, the fluid must be protected
from freezing. The fluid fill requires careful design with heat tracing and insulation to keep it in the liquid phase and to keep
both the high-pressure and low-pressure legs of the tubing at the same temperature (maintaining the liquid fill at the same
density). If practical, use a liquid leg fill fluid other than water. Methanol is a possible substitute, but dibutyl phthalate is the
recommended fill fluid because it does not mix with water and remains liquid throughout a broad temperature range of,
–31…644° F (–35…340° C).
MPORTANTI
Be careful when using dibutyl phthalate. Follow all hazardous material guidelines (CAS No: 87-74-2).
Meter Installation for Steam Service
Page 17June 2018 DPM-UM-00206-EN-03

Side View
HI LO
Flow
By-pass
Valve
Front View
Filling Crosses
(Fill with water to same level)
DP Transmitter or
Direct Read Gage
HI LO
Figure 8: Typical horizontal installation for steam
Flow
Side View
Instrument Taps Not In the Same Plane
HI LO
By-pass
Valve
Front View
Filling Crosses
(Fill with water to same level)
DP Transmitter or
Direct Read Gage
HI LO
Figure 9: Optional horizontal installation for steam
Meter Installation for Steam Service
Page 18 June 2018DPM-UM-00206-EN-03

Vertical Meter Installation
For steam service installations in which the meter is oriented vertically, extend the piping from the upstream pressure tap
horizontally to a T-connector. The T-connector enables a plug to be installed at the top for liquid filling purposes to avoid
overheating of the differential pressure cell. Position the manifold block directly below, at a distance that keeps the steam at a
safe operating temperature when it reaches the differential pressure transmitter. Extend both lines to the T-connectors.
NOT:NThis configuration results in a head difference in the differential pressure lines and the differential pressure
transmitter must be zeroed when zero flow has been established in the main line.
When the process is turned off, particulates may settle into the low-pressure port. Flush the low-pressure port with an inert
fluid before starting the meter.
Transmitter Calibration
Calibrate the transmitters (differential pressure and/or multi-variable) according to the manufacturer’s recommendations,
appropriate national or company standards and contractually agreed methodology. Consider the service in which the
Gemini Cone meter and transmitter are installed and operated.
HI
LO
Flow
HI
LO
Flow
DP Transmitter
or
Direct Read Gage
Side View Front View
3-Valve Manifold
Filling Crosses
(Fill with water
to same level)
Figure 10: Typical vertical installation for steam
Meter Installation for Steam Service
Page 19June 2018 DPM-UM-00206-EN-03

SYSTEM MODIFICATIONS
Square Root Error
Differential pressure measurement is only accurate for steady-state flow. Flow pulsation caused by reciprocating compressors,
defective regulators, and like equipment can cause mis-registration of delivered volumes.
Significant errors occur when using differential pressure devices at the discharge of a reciprocating gas compressor where
pressure pulses may exceed 10% of static pressure. This causes a condition called square root error, which may be reduced by
the use of an acoustic filter.
Gauge Line Error
Gaseous fluids in small-bore pipes may start to oscillate due to an effect called gauge line error. It is a type of acoustic
resonance comprising of standing pressure waves, and usually occurs at a maximum of 1/4 wavelengths. A common cause
of this phenomenon is the use of impulse lines with a high length to diameter ratio. To help prevent gauge line error, keep
impulse lines as short as possible, and use large impulse line diameters where possible. It also helps to keep impulse line
diameters constant along their length. The direct mounting of the transmitter to the meter can help reduce or even eliminate
the effects of gauge line error. Direct-mount manifolds are available from leading manifold manufacturers.
Elevation and Temperature Eects in Piping
In liquid service, it is important to keep vertical elevation equal between the two impulse lines. If one liquid-filled leg is longer
than the other, the hydrostatic head of the lines will vary, resulting in inaccurate differential pressure measurement.
Similarly, if the temperature of liquid in one leg is different from the temperature of liquid in the other leg, the density of the
fluid will be different, resulting in inaccurate differential pressure measurement. This most often occurs when one leg of the
tubing is in bright sun and the other leg is shaded. To minimize the effects of temperature differences in the vertical legs of
impulse lines, shade both of the legs from the sun. The effect of temperature differences is more notable in liquid service
installations; gas service is not as prone to DP error due to varying line temperatures.
SPECIFICATIONS
Applications Liquids, steam, air and industrial gases
Pipe Sizes
Wafer 1…4 in. (25…102 mm)
Threaded and Socket Weld 1/2…2 in. (12…51 mm)
Flanged Mount 1…24 in. (25…609 mm)
Butt Weld 1/2…24 in. (12…609 mm)
Repeatability ± 0.1% or better
Flow Range 10:1 and greater
Accuracy ± 0.5% of actual flow
Standard Beta Ratio 0.40…0.80 (special betas available)
Permanent Pressure Loss Varies with beta ratio and DP
Installation Piping
Requirements
Typically 0…3 diameters upstream and 0…1 diameters downstream of the cone are required,
depending on fittings or valves in the adjacent pipeline (See “Installation” on page9 for the
straight pipe requirements of your application)
Construction Materials 304/304L, 316/316L stainless steel, A106 carbon steel, other materials on request
End Fittings Threaded (NPT), flange, wafer, socket, and butt weld, other end connections on request
Approvals CRN
System Modications
Page 20 June 2018DPM-UM-00206-EN-03