Technical Guide
DAN-LIQ-Turbine Meter-TG-0807
August 2007
Liquid Turbine Flow Meters
Daniel® Liquid Turbine
Flow Meter Technical
Guide
www.daniel.com
Technical Guide
DAN-LIQ-Turbine Meter-TG-0807
August 2007
TABLE OF CONTENTS
Turbine Meter Parameters ............................................................................................................................. 1
The Daniel Series 1200 and 1500 Liquid Turbine Flow Meter Systems ........................................................ 2
Turbine Meter Theory .................................................................................................................................... 3
Patented Floating Rotor................................................................................................................................. 4
Magnetic Pickoff of Rotor Velocity ................................................................................................................. 5
Turbine Meter Rotor and Bearing Design ...................................................................................................... 6
Rimmed Rotors for Higher Resolution ........................................................................................................... 7
Daniel Series 1200 Liquid Turbine Flow Meter .............................................................................................. 8
Daniel Series 1200 Liquid Turbine Flow Meter Design Features .................................................................. 9
Daniel Series 1200 Liquid Turbine Flow Meter Materials of Construction ................................................... 10
Daniel Series 1500 Liquid Turbine Flow Meter ............................................................................................ 11
Daniel Series 1500 Liquid Turbine Flow Meter Design Features ................................................................ 12
Daniel Series 1500 Liquid Turbine Flow Meter Materials of Construction ................................................... 13
Rangability of Liquid Turbine Flow Meters...................................................................................................14
Liquid Turbine Flow Meter Performance with Different Specic Gravities ...................................................14
Daniel Series 1500 Liquid Turbine Flow Meter Specic Gravity Adjustments ............................................. 15
Meter Performance in High Viscosity Liquids .............................................................................................. 16
Installation and Operating Recommendations............................................................................................. 17
Back Pressure .............................................................................................................................................18
Turbine Meter Instrumentation ....................................................................................................................19
FOREWORD
Daniel Measurement and Control is a recognized leader in the eld of ow measurement. The Company is
engaged solely in the design and manufacture of ow measurement equipment for custody transfer and scal
duty applications for both gas and liquid. Daniel offers both individual products and systems, with the largest
installed base of packaged meter and prover systems. Daniel continues to be the leader in measurement
systems.
Daniel liquid turbine ow meters are the product of a continuous development process, and offer the best solution
for modern liquid measurement requirements.
The range of liquid turbine ow meters includes the Daniel Series 1200 and 1500 Liquid Turbine Flow Meters,
each of which is designed for specic industry segments. The Daniel Series 1200 Liquid Turbine Flow Meter is
designed for applications in loading terminals and is used on a variety of rened product loading applications.
The Daniel Series 1500 Liquid Turbine Flow Meter utilizes proven technology in a robust package designed for
pipeline applications.
Daniel turbine meters have been proven on a variety of liquid metering applications, including crude oil,
rened products, LPG, liquid ethylene and many other liquids. The characteristics of the turbine meter, which
include excellent repeatability, longevity and simplicity, lend the technology to an increasing number of liquid
measurement applications.
Technical Guide
DAN-LIQ-Turbine Meter-TG-0807
August 2007
TURBINE METER PARAMETERS
These ve terms are the most widely discussed parameters of turbine meter applications.
Linearity is the measure of variation in signal output across the nominal ow range of the meter. The turbine
meter will have a nominal K-factor (number of pulses output for a given volume measured) and this value varies
across the ow range of the meter. Linearity is a measure of the variance of actual output from the average
K-factor. With modern electronics, linearization of the meter registration is possible within a ow computer, and
thus further improvements in measurement accuracy is possible.
Repeatability is the ability of a meter to indicate the same reading each time the same ow conditions exist.
Turbine meters exhibit excellent repeatability and, for many control applications, this is the most important
parameter to be considered.
Accuracy is a measure of how close to true or actual ow the instrument indication may be. It is generally
expressed as a percent of true volume for a specic ow range. This is a “worst case” rating. Accuracy at a
particular ow rate may be an order of magnitude better than “rated ow range accuracy.”
Resolution is a measure of the smallest increment of total ow that can be individually recognized, normally
dened by a single pulse. Turbine meters have an inherently high resolution.
Range is the ratio of maximum ow to minimum ow over which the specied linearity will be maintained. Normal
range (or “turn-down”) is given as 10:1, although this may be exceeded in many cases, depending on meter size
and required linearity.
Figure 1 - Flow Ranges
+0.15%
–0.15%
+0.02%
–0.02%
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Technical Guide
DAN-LIQ-Turbine Meter-TG-0807
August 2007
THE DANIEL® SERIES 1200 AND 1500 LIQUID TURBINE FLOW METER SYSTEMS
The Daniel Series 1200 and 1500 Liquid Turbine Flow Meter Systems combine turbine meters and electronic
instrumentation to measure volumetric total ow and/or ow rate. Each Daniel turbine meter comprises of a
cylindrical housing containing a precise turbine rotor assembly. The magnetic pickoff, or pickoffs, are mounted
in a boss on the meter body. As uid passes smoothly through the ow meter, it causes the rotor to revolve with
an angular velocity proportional to ow. The rotor blades or rim buttons passing through the magnetic eld of the
pickoff generate a pulsing voltage in the coil of the pickoff assembly. Each voltage pulse represents a discrete
volume. The total number of pulses collected over a period of time represents the total volume metered.
The sinusoidal signal from each pickoff has low amplitude and may not normally be relied upon for
transmission distances over 20 feet (6 meters). The signal must, therefore, be amplied. This is achieved with a
preamplication board mounted on the turbine meter. These pulse signals are typically transmitted to control room
instrumentation such as ow computers, and may also be required to input to prover computers which calculate,
display, transmit, control or record the ow sensed by the rotor. The results may be displayed as pulse-counts or
standard engineering units, such as gallons, barrels, etc.
All Daniel Series 1200 and 1500 Liquid Turbine Flow Meters have, as standard, the Universal Mounting Box
(UMB) which may be tted with one or two pickoffs and the dual channel preamplier. The pickoff mountings are
oriented so that the outputs from the pickups are 90º electrically out of phase. The Daniel Series 1500 Liquid
Turbine Flow Meter may be supplied with two UMBs, offering up to four pulse outputs. Alternate pairs across the 2
UMBs are also 90º electrically out of phase.
Figure 2 - Liquid Turbine Flow Meter System
Flow Computer
Daniel manufactures the Series 1200 and 1500 Liquid Turbine Flow Meters, the adjacent tube sections, and the
electronic instrumentation. Each meter is precisely ow calibrated before shipment.
The Meter Systems are used to provide measurement information in uid transport, petroleum and chemical
processing, custody transfer of liquids, blending systems, and in product batching in eld or plant operations. The
repeatability of the systems ensures quality measurement of uids over a wide range of ow rates, temperatures,
compositions and viscosities.
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Technical Guide
DAN-LIQ-Turbine Meter-TG-0807
August 2007
Daniel® Valves In Load Rack Duty
TURBINE METER THEORY
The basic theory behind Daniel’s electronic liquid turbine meters is relatively simple. Fluid ow through the meter
impinges upon the turbine blades which are free to rotate about an axis along the center line of the turbine
housing. The angular (rotational) velocity of the turbine rotor is directly proportional to the uid velocity through
the turbine. These features make the turbine meter an ideal device for measuring ow rate.
The output of the meter is taken by an electrical pickoff(s) mounted on the meter body. The output frequency of
this electrical pickoff is proportional to the ow rate. In addition to its excellent rangeability, a major advantage
of the turbine meter is that each electrical pulse is also proportional to a small incremental volume of ow. This
incremental output is digital in form, and as such, can be totalized with a maximum error of one pulse regardless
of the volume measured.
The turbine meter and associated digital electronics form the basis of any liquid metering system. An expanding
blade hanger assembly holds the turbine rotor in alignment with the uid ow. The angle of the turbine blades to
the stream governs the angular velocity and the output frequency of the meter. A sharper blade angle provides a
higher frequency output. In general, the blade angle is held between 20º and 40º to the ow. Lower angles cause
too low of an angular velocity and loss of repeatability, while larger angles cause excessive end thrust.
FLOW RATE IS PROPORTIONAL TO ANGULAR VELOCITY
Figure 3 below is a cross section of the internals of a Daniel turbine meter. Flow through the turbine meter is from
left to right. The forward and rear suspension act as ow guides so that uid motion through the meter is parallel
to the meter centerline. Flow impinging upon the angular blade causes the rotor to spin at an angular velocity
proportional to ow rate.
Figure 3 - Liquid Turbine Flow Meter Cross Section
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Technical Guide
DAN-LIQ-Turbine Meter-TG-0807
August 2007
Figure 4 - Rotor Assembly Cross Section
PATENTED* FLOATING ROTOR
Flowing uid enters the turbine through the forward suspension. When it encounters the sharp angle of the cone,
the stream is deected outward, increasing in velocity and causing a slight static pressure drop. As the uid
leaves the blade area, ow has redistributed. Velocity is reduced slightly and the static pressure has increased
proportionally.
The difference between the two velocity pressures causes the rotor to move upstream into the uid ow. This
upstream force would be great enough to cause the rotor to strike the forward thrust bearing, were it not for
the slight offset. The cross sectional area of the cone is slightly smaller than that of the rotor hub so that some
of the ow impinges directly upon the rotor hub, generating a downstream thrust. As a result, the rotor oats in
balance between upstream and downstream cones, pushed forward by the pressure difference across the blades
and pushed backward by the ow impingement. The only bearing surface other than the measured uid is the
cemented carbide sleeve bearing insert. (See Figure 4)
In bi-directional meters, the downstream cone is replaced by a second upstream cone and rangeability in the
reverse ow direction is reduced.
* U.S. PATENT NO. 3,948,099, PATENTS IN OTHER COUNTRIES
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Technical Guide
MAGNETIC
SENSORS
(PICKOFFS)
CLAMP
O-RING
BLADES
PICKOFF #1 PICKOFF #2
INSULATOR
UNIVERSAL
MOUNTING
BOX
(UMB)
UMB
MOUNTING
BOX PAD
THIS 1/2 PULSE
IS NOT USED
BY READOUTS
A
B
C
A
ONE
PULSE
B
C
ONE
UNIT
VOLUME
THIS 1/2 PULSE
IS NOT USED
BY READOUTS
A
ONE
PULSE
B
C
ONE
UNIT
VOLUME
DAN-LIQ-Turbine Meter-TG-0807
August 2007
Surge And Pressure Relief Valves
MAGNETIC PICKOFF OF ROTOR VELOCITY
The angular velocity of the turbine rotor is taken through the turbine meter wall by means of a magnetic pickoff.
The stainless steel meter body is non-magnetic and offers negligible effect on a magnetic eld set up by a
permanent magnet in the pickoff coil.
Turbine blades, made of a paramagnetic material (which properties cause it to be attracted by a magnet),
rotate past the pickoff coil, generating irregular shaped voltage pulses. The frequency of these pulses is linearly
proportional to the angular velocity of the rotor and thus to the ow rate. Additionally, each pulse is incrementally
proportional to a small unit of volume. The amplitude of the pulses will vary in proportion to blade velocity but is
not considered in the measurement process. Flow rate and total ow information is transmitted by frequency and
by counting (totalizing) the pulses.
The permanent magnet produces a magnetic eld which passes through the coil and is concentrated to a small
point at the pickoffs. In Figures 5 and 6 below, as a turbine blade (A) moves into close proximity to the pickoff
point, its magnetic properties cause the magnetic eld to deect to accommodate its presence. This deection
causes a voltage to be generated in the coil. As the blade passes under the pickoff point (B), this voltage decays,
only to build back in the opposite polarity as the leaving blade - now in position (C). This causes the magnetic
eld to deect in the opposite direction. So as each blade passes the pickoff, it produces a separate and distinct
voltage pulse. Since the uid surrounding each blade represents a discrete unit of volume, each electrical pulse
also represents a discrete unit of volume. Turbine meter output is rated in pulses per gallon, pulses per liter, or
other standard engineering units.
Figure 5 - Assembly of Daniel® UMB showing
dual pickoff conguration
Figure 6 - Voltage Output, Peak to Peak
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