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Liquid Flow Meters

liquid flow meters

As of 2021 the global market for all flow meters is about over 9 billion USD with a growth rate of 6-7%. Liquid flowmeters represent over 80% of the total flow markets. Not only liquid flow measurements are the most used flowmeters but it also the most diversified technological choices based on a user’s application requirements.

Plant efficiency and product outputs necessitates accurate measurement of liquid flowmeters. Therefore, measuring the flow of liquids is a critical need in many industrial plants. The ability to conduct accurate flow measurements is so important that it can make the difference between making a profit or taking a loss. Virtually all industries use liquids in their process and inaccurate liquid flow measurements or failure to take measurements can cause serious (or even disastrous) results.

Flow vs Velocity
Flow vs Velocity

With most liquid flow meters, the flow rate is determined inferentially by measuring the liquid’s velocity or the change in kinetic energy. Velocity depends on the pressure differential that is forcing the liquid through a pipe or conduit. Because the pipe’s cross-sectional area is known and remains constant, the average velocity is an indication of the flow rate. The basic relationship for determining the liquid’s flow rate in such cases is:

Q = V x A
where
Q = liquid flow through the pipe
V = average velocity of the flow
A = cross-sectional area of the pipe


Q above is volumetric flow rate and volumetric flow meters are the most traditional flow metering technologies. This means that the meter output or displayed value on the screen is in volumetric units of measure, such as Gallons Per Minute (GPM), Liters Per Minute (LPM), or many other flow units. Other factors that affect liquid flow rate include the liquid’s viscosity and density, and the friction of the liquid in contact with the pipe, as well whether a mass flow measurement is better forgiven liquid flow application.

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The effects of density on a fluid

Density is a measure of mass per unit of volume. The average density of an object equals its total mass divided by its total volume. An object made from a comparatively dense material (such as iron) will have less volume than an object of equal mass made from some less dense substance (such as water). The formula for density is d = M/V, where d is density, M is mass, and V is volume. Density is commonly expressed in units of grams per cubic centimeter. For example, the density of air is 1.2 kilograms per cubic meter. For flow measurement mass flow = volumetric flow (Q) tines density(d).

The volume of liquid changes with the changes in pressure and temperature, while its mass never changes. Volumetric liquid flow measurement is the original techniques to measure liquid flows measuring the volume of liquid passing through a pipe or a channel. However, in liquids, the effects of fluctuating temperature and pressure are not as critical as in gas flow measurement. Since volumetric flowmeters are cheaper with many measurement techniques available, they represent over 80% of all liquid flow measurement techniques.

The effects of viscosity on a fluid

Viscosity is a measure of a fluid in this case a liquid’s resistance to flow. It describes the internal friction of a moving liquid. A liquid with large viscosity resists motion because its molecular makeup gives it a lot of internal friction.  Therefore, some liquid flow meters are better in handling viscosity than others. Liquid flow measurement users must take into account the effects of viscosity on the flowmeter technologies chosen.

Smartmeasurement has the most comprehensive liquid flow meters offering our customers a smart solution for their individual application requirements.

Volumatic measurement
Volumetric Liquid Flow

Volumatic measurement can be done with the following flow meter technologies

Differential Pressure (DP) Flow Meters are a volumetric flow technology which is a flow body containing some type of throttle restriction with known characteristics, such as a venturi, orifice, cone, or segmented wedge. This restriction creates a differential pressure between a pressure tap (P1) upstream of the restriction and a pressure tap downstream of the restriction (P2) which is proportional to the square of the volumetric flow rate. For a more detailed discussion of the principle of operation, please go to https://www.smartmeasurement.com/flow-meters/differential-pressure/measuring-principle.  SmartmeasurementTM offers the Acone differential pressure liquid flow meters offering the best accuracies and pressure drops than any other differential pressure (DP) flow technologies.

Magnetic Flow Meters also known as mag meters are volumetric flow meters having two non-moving parts that contact the measured fluid media – a liner which protects the flow body from the fluid and a pair of electrodes which detect the velocity of the flowing fluid. Compared to traditional mechanical flow measurement techniques such as turbine and positive displacement which rely on rotating mechanical gears and bearings, the mag meter’s simple construction provides for longer life, less maintenance, lower pressure drops, and overall lower cost of ownership. This design allows the mag meter to be used with virtually any conductive liquid regardless of density, viscosity, chemical composition, or fluid condition/particulate count. SmartmeasurementTM offers a wide variety of magnetic or mag flow metering choices in our ALMAG series.

Positive Displacement (PD) Flowmeters, are volumetric flow metes employing one of the oldest-known flow measurement techniques, are widely used in industry and have one of the largest install bases of any flow meter technology. Positive Displacement Flowmeters feature two precisely machined rotating members inside a measuring chamber of known volume which may be used to accurately determine volumetric flow rate as a function of the rotors’ velocity. A more detailed discussion of the principle of operation can be found at: https://www.smartmeasurement.com/flow-meters/positive-displacement/measuring-principle.  SmartmeasurementTM offers a variety of PD meters with our ALPD series. 

Turbine Flowmeters measure volumetric flow, where flow passing through the tube is measured as a function of the mean velocity of the streaming fluid.  Turbine flow meters may be configured to measure either gas or liquid flow rates. A low mass turbine wheel carried axially in the tube is rotated by the fluid; the RPM of the turbine wheel is directly proportional to the mean fluid velocity within the tube. For a more detailed discussion of the principle of operation please go to: https://www.smartmeasurement.com/flow-meters/turbine/measuring-principle.  SmartmeasurementTM offers our ALTM series of turbine flow meters for liquid flow measurement with variety of style fittings and sizes. 

Ultrasonic flow meters are volumetric flow meters offering a number of advantages over other liquid flow measuring technologies. The most distinct of these advantages is the non-invasive nature of ultrasonic measuring technique: fluid flow can be measured by clamping a pair of transducers onto the outside of the pipe without contacting the measured fluid. Ultrasonic as well as Magnetic liquid flow meter technologies represent over 60% of all liquid flow measurement techniques. 

Fluid velocity is measured by sending an ultrasonic pulse from an upstream transducer to a downstream transducer and back again. The measured difference in the amount of time that each pulse takes to traverse the pipe is directly proportional to the mean fluid velocity. Ultrasonic flowmeters use this measured velocity to calculate the liquid flow rate based on user-entered information about the process application. For a more detailed discussion of our ultrasonic flowmeter’s principles of operation, please visit https://www.smartmeasurement.com/ultrasonic-technology/

SmartmeasurementTM offers the most comprehensive selection of ultrasonic liquid flow measurements with our ALSONIC series of products. 

Read more about the different types of Ultrasonic Flow meters:

Open Channel Flow Meter
Ultrasonic BTU Meters
Portable Ultrasonic Flow Meters
Clamp On Ultrasonic Flow Meters

Variable Area (VA)flowmeters measure volumetric flow of liquids and are simple and versatile devices that operate at a relatively constant pressure drops. Variable Area (VA) flowmeters make use of a float, piston or vane placed inside a flow body, which changes position in response to changes in flow rate of the measure fluid media. The position of the float, piston or vane provides a direct visual indication of flow rate. Either the force of gravity or a spring is used to return the float to its resting position when the flow lessens.  For a more detailed discussion of the principle of operation, please go to: https://www.smartmeasurement.com/flow-meters/variable-area/measuring-principle. SmartmeasurementTM offers our ALVATM series of metal tube VA flow meters for liquid flow measurement without external power and dial type indicator or with intelligent electronics requiring external power. 

Vortex flow meters are volumetric flow meters that can measure all three phases of a fluid; gas, liquid and steam.  All though it is used for liquid flow metering the above other flow metering technologies are better and therefore vortex measurements are mainly used in steam and gas applications. Vortex flow sensing technology relies on measuring the number of vortex pulses generated by a bluff body immersed in the flow stream. A bluff body is machined inside the vortex flow meter; as flow pass through this bluff body, vortices are generated in either side of the bluff body. The flow rate can be determined by measuring the number of vortices.  For a more detailed discussion of the principle of operation, please go to: https://www.smartmeasurement.com/flow-meters/vortex/measuring-principle. SmartmeasurementTM offers our ALVT series of vortex flow meters for liquid flow measurement comes in both flanged or wafer connections. 

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Mass Flow Measurement for Liquids

Coriolis flow metes. There are a number of flow measurement applications that require the flow rate to be measured in mass units, including chemical mixing/batching, custody transfer, and emissions monitoring. Making use of volumetric flowmeters in these applications can prove to be challenging because converting the volumetric units to mass units requires the volumetric reading to multiplied by a media density value. For liquid fluid media, the density value changes with temperature; for gas media the density changes with both temperature and pressure. The changing density leads to inaccuracy when volumetric meters are applied in these situations. Mass Flowmeters solve this problem by providing a direct mass flow reading which is immune to changes in process temperature and pressure. SmartmeasurementTM’s ALCM Coriolis flowmeters offer a perfect solution for liquid mass flow measurement solution. 

SmartmeasurementTM has the most comprehensive liquid flow meters offering our customers a smart solution for their individual application needs. 

 

Read about the other types of Flow meters:

Gas Flow Meters
Steam Flow Meters
Coriolis Flow Meters 

Installation Methods

Primary Application

Special Features

Main Markets

Installation Methods

Primary Application

Special Features

Main Markets

Installation Methods

Primary Application

Special Features

Main Markets

Installation Methods

Primary Application

Special Features

Main Markets