Flowmeters - ultrasonic
flowmeters
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Doppler and transit-time flowmeters are
two types of ultrasonic flow meters that have been extensively
used in liquid applications around the world, certain companies
are now applying the transit time method for gas flow measurement
applications either flare gas or custody transfer meters for
natural gas. We would like to explain the use of ultrasonic
flow meters where they apply to liquid measurement and particularly
transit time method because it yields much greater accuracies
where it can be applied.
It is important to know what these two technologies are ,
and where they should be applied to in the field . Our ultrasonic
flowmeter as it is today , has gone through many technological
advances, especially those in electronic circuitry and with
the power of computers crunch numbers faster.
Now more updated signal processing is being used in many transit-time
flowmeter designs, battery power up to 15 hours and flow readings
obtained within seconds,
This has considerably eased the job of the flow survey company
and increased customer confidence in ultrasonic meters . Survey
companies can now measure more pipes than ever before. Recently
our company's flow survey unit reports being able to make
more than 35 spot checks of liquid flow rate a day. Both transit
time and doppler ultrasonic flowmeters may use clamp-on sensors
with their associated assemblies and detect flow rate from
the outside of the pipe without stopping the process or cutting
through the pipe. The applications for this type of technology
are manifold because now we are able to make sure our old
or new pump is working to its capacity, gather data for flow
balancing , check if our permanently installed meters are
measuring incorrectly or are in need of maintainance , or
simply clamp on a flow meter where there is no flowmeter or
where other flowmeters make it impractical for installation
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Figure 10 is clamp on ultrasonic
flow meter transducers are installed on the same side of the
pipe measuring a liquid flow. The transducers are either clamped
on with chains or sit in a rail track. It takes virtually
minutes to install. It is a typical installation of an Eesiflo
transit time ultrasonic flowmeter transducers
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What this ultrasonic
flow meter is able to do:
The ultrasonic meter can measure water, waste water, hydrocarbon
liquids, organic or inorganic chemicals, milk, beer, lube
oils and the list goes on. The basic requirement is that
the fluid is ultrasonically conductive and has a reasonably
well formed flow. Clamp-on ultrasonic flowmeters measure
flow through the pipe without any contact with the process
media, ensuring that corrosion and other effects from the
fluid will not affect the workings of the sensors or electronics.
In addition the Eesiflo clamp-on ultrasonic flowmeter simplifies
installation and maintenance which is a plus in situations
where downtime and set up costs need to be controlled. Whether
this flow meter is a portable or permanently installed unit,
there are several advantages in using it, such as a redundancy
to already installed flowmeters or surveying existing meters
in a number of locations throughout a municipality or process
plant.
Typically an Eesiflo ultrasonic flow meter operates on pipe
diameters from 50 mm to 6500 mm and fluid temperatures from
-30ºC to >200ºC ; and flow rates from 0.01
to >25 m/s. All of our standard models are DUAL CHANNEL
as standard. Operators can clamp 2 sets of sensors on the
same pipe or other pipes. Flow rates can be added or subtracted
from each other . Most competitors will charge additionally
for a dual channel feature
Measurement accuracy can be in the range 1 to 3 percent
of measured value of 0.5 percent with process calibration
depending on the application. The portable microprocessor-based
electronics unit provides a local backlit display and has
a keypad for setting up and diagnostics . The flowmeter
can read flow units in common imperial or metric units ,
measures flow in both directions, can store up to 100,000
data points internally, give analog or serial outputs and
has optional inputs for RTD’s and thickness gauges. The
Heat quantity option is an excellent tool for the HVAC industry
where a T1 and T2 can be applied into the equation
The Electronics unit can log data for measuring sites. It
can also provide a PC interface via RS-232 serial communication,
and an output of 4-20 mA DC for operating a digital controller,
DCS, PLC, or recorder.
The flowmeter has a built-in, rechargeable battery and can
operate continuously for 15 hours. This is a big difference
because now you can measure all day with a portable without
losing time and money.
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Layman’s explanation of transit time |
The ultrasonic transducers can be mounted in one of two
modes. The upstream and downstream ultrasonic transducers
can be installed on opposite sides of the pipe (diagonal
mode) or on the same side (reflect mode)
The electronics unit will measure internally ,the time
it takes for signals to transmit from one transducer to
another. At zero flow , we see no difference in time,
but when flow is introduced,time for the transmission
of signal from the downstream transducer to the upstream
transducer will take longer than the upstream to downstream.
Hence we will see a time differential which has a relationship
with the velocity of the fluid being measured. Knowing
the internal diameter of the pipe , we can now calculate
a volumetric flow for the liquid.
Obviously there are factors such as solid and liquid refractive
angles , error transmissions and poor sonic conductivity
at times, but the inbuilt software will normally deal
with these by telling us how we should space the transducers
and by rejecting erroneous data it receives.
It is important when installing an ultrasonic transit
time flow meter to select a location where we would find
the most fully formed flow profile, this means that we
should avoid bends and try to install our meters on straight
runs of pipe. A rule of thumb in the industry is to give
at least 10 diameter lengths upstream and 5 lengths downstream.
If we are measuring liquids such as water with known properties
and sonic velocities we can further check our measurements
by several diagnostic methods. Using the keypad we can
see what the actual sonic velocity of water is being measured
on our installation. This is one of the simplest and quickest
methods.
Should we find that we are in a situation where the amount
of entrained bubbles or solids is so great that no sonic
propagation is possible from one transducer to the other,
we simply switch into a Doppler mode measurement by pressing
one button on the keypad. The Doppler method relies on
the existence of solid particles or bubbles in the liquid
being measured
Measuring in ultrasonic Doppler mode is not the preferred
mode for most of the applications where we will find our
meters being used, but there are some applications which
warrant its use and we therefore apply it.
If you have read this far and would like to know even
more about this technology and Eesiflo, please do not
hesitate to contact us. Our people are all qualified engineers
and have many years of field experience with ultrasonic
flow meters
If you did
not find what you were looking for here try a human edited
directory http://www.dmoz.org
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flow meter calibration
variable area flowmeter
ultrasonic flow meter
digital flowmeter
oil flowmeter
venturi flowmeter
portable flowmeter
flow meter rental
sewer flowmeter
thermal mass flowmeter
insertion flowmeter
meter flow
ultrasonic flow meters
mass air flowmeter
high viscosity flowmeter
open channel flowmeter
magnectic flowmeter
orifice flowmeter
low flowmeter
water meter flow
ultrasonic flow meter
crosscorrelation flowmeter
ultrasonic flow
water plant flowmeter
inline flowmeter
sonic flowmeter
differential pressure flowmeter
ultrasonic doppler
ultrasonic flowmeters
magnetic flowmeters
electromagnetic flowmeters
flowmeters manufacturer
flowmeters supplier
gas flowmeters
vortex flowmeters
variable area flowmeters
feedthrough flowmeters
water flowmeters
digital flowmeters
doppler flowmeters
flow meter
turbine flow meter
peak flow meter
flow meter manufacturer
water flow meter
air flow meter
magnetic flow meter
mass flow meter
electromagnetic flow meter
flow meter supplier
flow meter directory
gas flow meter
coriolis flow meter
fuel flow meter
liquid flow meter
vortex flow meter
positive displacement flow meter
flow meter water
flow meter calibration
variable area flow meter
brook flow meter
digital flow meter
oil flow meter
venturi flow meter
portable flow meter
flow meter rental
sewer flow meter
thermal mass flow meter
insertion flow meter
meter flow
neptune flow meter
mass air flow meter
high viscosity flow meter
open channel flow meter
magnectic flow meter
orifice flow meter
low flow meter
water meter flow
badger flow meter
crosscorrelation flow meter
signet flow meter
water plant flow meter
inline flow meter
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sonic flow meter
differential pressure flow meter
the function of flow meter and non return valve
in heat pump
company flow meter flow monitor flow computer and
cu
flow meter
daniel flow meter
flow meter
flow meter turbine flowmeters
ultrasonic flowmeters
magnetic flowmeters
electromagnetic flowmeters
flowmeters manufacturer
flowmeters supplier
gas flowmeters
vortex flowmeters
variable area flowmeters
brook flowmeters
feedthrough flowmeters
water flowmeters
digital flowmeters
doppler flowmeters
ultrasonic flowmeter
turbine flowmeter
peak flowmeter
flow meter manufacturer
water flowmeter
air flowmeter
magnetic flowmeter
mass flowmeter
electromagnetic flowmeter
flow meter supplier
flow meter directory
gas flow meter
coriolis flowmeter
fuel flowmeter
liquid flowmeter
vortex flowmeter
positive displacement flowmeter
flow meter water
flow meter calibration
variable area flowmeter
ultrasonic flow meter
digital flowmeter
oil flowmeter
venturi flowmeter
portable flowmeter
flow meter rental
sewer flowmeter
thermal mass flowmeter
insertion flowmeter
meter flow
Xytec 7300B
ultrasonic flow meters
mass air flowmeter
high viscosity flowmeter
open channel flowmeter
magnectic flowmeter
orifice flowmeter
low flowmeter
water meter flow
ultrasonic flow meter
crosscorrelation flowmeter
ultrasonic flow
water plant flowmeter
inline flowmeter
sonic flowmeter
differential pressure flowmeter
ultrasonic doppler
ultrasonic flowmeters
magnetic flowmeters
electromagnetic flowmeters
flowmeters manufacturer
flowmeters supplier
gas flowmeters
vortex flowmeters
variable area flowmeters
feedthrough flowmeters
water flowmeters
digital flowmeters
doppler flowmeters
Interesting links on Flowmeters
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