W. H. Cooke & Co., Inc.

Manufacturer of thermocouples and RTD's. Supplier of industrial controls, heaters, and sensors since 1963.

Phone:717-630-2222

Email: sales@whcooke.com

Flow Meters

Manufacturers

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Featured Products

    • Sure Flow SERIES Y, U, F, M High Capacity Indicators, Switches, Transmitters

    • Seametrics IP800-SERIES

    • Endress & Hauser Proline Promass 40E Coriolis flowmeter

    • Kobold KAL-A - Thermal Flow Sensor for Water-Based Liquids

    • Endress & Hauser Proline Prowirl 73W Vortex flowmeter

    • Endress & Hauser Proline Promag 10P Electromagnetic flowmeter

    • Dwyer Series VFA & VFB Visi-Float® Flowmeter

    • Universal Flow Meter MH-CSB80GM-16-100CS.8871-A0NR 80GPM

    • Niagara WPX 222

    • Endress & Hauser Proline Prosonic Flow 91W Ultrasonic Flowmeter

    • Kobold DUK-12-G4H-C34P-BY Kobold ultrasonic Flowmeter

    • Dwyer GFM Series

    • Dwyer WM2-A-C-06 1.5" Multijet Cold Water Meter

    • Kobold DPM-1550DR1675 Pelton Wheel Flow Sensor (equal to DPM-1550G2C34PY)

    • Dwyer Series VFLO Venturi Flowmeter with Magnehelic® Gage

    • Dwyer Series OP Orifice Plate Flowmeter

    • Kobold TMU - High Performance Coriolis Mass Flowmeter

    Featured Items:

    • Sure Flow SERIES Y, U, F, M High Capacity Indicators, Switches, Transmitters

    • Seametrics IP800-SERIES

    • Endress & Hauser Proline Promass 40E Coriolis flowmeter

    • Kobold KAL-A - Thermal Flow Sensor for Water-Based Liquids

    • Endress & Hauser Proline Prowirl 73W Vortex flowmeter

    • Endress & Hauser Proline Promag 10P Electromagnetic flowmeter

    • Dwyer Series VFA & VFB Visi-Float® Flowmeter

    • Universal Flow Meter MH-CSB80GM-16-100CS.8871-A0NR 80GPM

    • Niagara WPX 222

    • Endress & Hauser Proline Prosonic Flow 91W Ultrasonic Flowmeter

    • Kobold DUK-12-G4H-C34P-BY Kobold Ultrasonic Flowmeter

    • Dwyer GFM Series

    • Dwyer WM2-A-C-06 1.5" Multijet Cold Water Meter

    • Kobold DPM-1550DR1675 Pelton Wheel Flow Sensor (equal to DPM-1550G2C34PY)

    • Dwyer Series VFLO Venturi Flowmeter with Magnehelic® Gage

    • Dwyer Series OP Orifice Plate Flowmeter

    • Kobold TMU - High Performance Coriolis Mass Flowmeter

    • Flow-Mon USA flow products combine flexibility, reliability, and quality for cost effective sure flow solutions in liquids, air, and gases. These flow instruments are field proven to be dependable, durable, and long lasting, even in the most difficult industrial applications. Flow-Mon USA monitors provides direct reading indication of flow rate with optional electrical switches and transmitter outputs. Available in a variety of metal materials, these monitors are also offered in PVC and Teflon construction for corrosive fluids, or for use in corrosive environments.

    • High-quality ruby bearings for excellent low-flow performance and long life. One easily-replaced moving part. Pickup exerts no magnetic drag on the rotor. Square-wave frequency output can connect directly to PLC's or counter controls. Indicator or transmitter can be mounted on the flowmeter or remote. Fittings are available in a wide variety of materials and sizes

    • Promass E has a long standing reputation as a cost efficient solution for basic Coriolis applications. Combined with the Promass 40 transmitter for low-end applications and direct integration, Promass 40E offers highly accurate measurement of liquids and gases for a wide range of applications.

    • The Model KAL-A thermal flow sensor for water-based liquids features KOBOLD’s revolutionary temperature-compensating electronics. The compact, one-piece thermal flow sensor with no moving parts provides reliable readings largely unaffected by temperature or physical characteristics of a wide variety of water-based process liquids. This breakthrough is made possible through the use of state-of-the-art microprocessor technology. The microprocessor can be field calibrated to the users’ liquid properties and operating range in a simple, five-minute set-up procedure. This intelligence, coupled with a no-moving-parts design, make the KAL-A flow sensor a superior performer in many applications. To further enhance the versatility of the KAL-A series, it is offered in a 3-A compliant version. The thermal flow sensor applies the KAL's advanced microprocessor-based technology to the problem of flow rate detection. It incorporates a non-linear, 4-20 mA, flow-rate output, the same 8-segment LED display found in the flow switch, with an optional PNP setpoint alarm relay if desired.

    • The wafer device Prowirl 73W is designed for the universal measurement of the volume flow of gases, steam and liquids. The proven and patented capacitive DSC sensor ensures high precision measured values even under the toughest process conditions. Prowirl 73W offers genuine, industry-compliant two-wire technology for seamless integration into existing infrastructures and control systems. In addition it provides an integrated temperature sensor and flow computer for mass and energy.

    • Promag P is the preferred sensor for applications with highest requirements in a multitude of industries. Combined with the Promag 10 transmitter for basic applications and direct integration, Promag 10P is dedicated for chemical and process applications with corrosive liquids and high medium temperatures. It will be the preferred solution for costumers aiming for minimized cost of ownership. Promag 10P is available in a compact or remote version.

    • The Visi–Float® flowmeter bodies are cut and precision machined from solid, clear acrylic plastic blocks. This construction not only produces a handsome finished product, but permits complete visual inspection. As a result, the Visi-Float® flowmeters are especially popular for medical and laboratory equipment applications.

    • These are variable area meters with a spring biased semi-circular vane that opens wider with more flow. They are installed in-line in any position. Straight pipe runs before or after the meter are not required. The simple mechanical connection directly drives pointers, switches and transmitters. The flowmeter has outputs both visual and electronic. Visual displays are either pointer (with inscribed scale) or numeric (digital LCD). Electronic outputs can be mechanical switch closure, 4-20 mA analog or both (for signal redundancy). The switches can be general purpose or rated for hazardous locations (all classes, groups and divisions). The 4-20 mA transmitters are Intrinsically Safe if used with approved barriers.

    • Liquid enters the precision metering insert containing the turbine rotor. The liquid pressure drives the turbine rotor rate of rotation proportional to the volumetric flow rate. The rotor's rotation is magnetically coupled to a hermetically sealed indicator or indicator/transmitter.

    • The Prosonic Flow W clamp-on sensor is specially designed for water and wastewater applications. Combined with the cost-effective Prosonic Flow 91 transmitter with push buttons, Prosonic Flow 91W is ideally suited for flow monitoring in the water industry.

    • KOBOLD DUK Series compact ultrasonic flowmeters are used for measuring, monitoring, and batching of low viscosity (water-like) fluids. These compact ultrasonic flowmeters with no moving parts work on the principle of run-time difference. Ultrasonic waves in the media are influenced by the rate of flow. It features two sensors mounted opposite one another in the pipeline, which function simultaneously as transmitter and receiver of ultrasonic signals. If no flow is present, the run-times of both signals are identical. If the media is flowing, the run-time of the signal against the flow will be longer than the signal with the flow. This run-time difference, determined by the KOBOLD DUK Series compact ultrasonic flowmeter’s microprocessor, is proportional to flow rate.

    • Series GFM Gas Mass Flow Meters combine a straight tube sensor with a restrictor flow element to provide high accuracy and repeatability. Flow rates are virtually unaffected by temperature and pressure variations. Actual gas flow is displayed in engineering units on a 3-1/2 digit, 90° tiltable LCD readout. Units can be used with Series GFT Flow Totalizer for applications requiring totalization. Series GFM includes a NIST traceable certificate.

    • The Series WM2 Multi-Jet Water Meter is ideal for commercial and industrial applications. The multi-jet design allows for simplicity and accuracy with wide flow ranges, even in low flow applications. The magnetically driven, hermetically sealed register will not leak or fog and is completely separated from the water. These water meters are designed for long service life and maintenance-free operation, even under harsh conditions. FEATURES: Magnetic drive – water is sealed from entering register. Dry dial won’t discolor or fade – hermetically sealed from the elements. Integral strainer that protects meters from particulate damage. Pointer-roller indicator. Frost resistant body. Includes two mounting adapters (couplings).

    • The KOBOLD DPM Series flow sensor uses the pelton wheel principle to measure the flow of water and water-based, low-viscosity liquids that are optically transparent. Liquid passes through a nozzle at the inlet of the flow body and is precisely directed onto a flat-blade pelton turbine. The flow sensor’s pelton turbine wheel rotates at a speed proportional to flow rate. The movement of the pelton wheel is detected optically, and the signal from the optical sensor is processed as an amplified pulse or 4-20 mA signal, both of which are proportional to flow rate. In addition to the DPM Series pelton wheel flow sensor’s compact design, the inlet flow is redirected via a nozzle; therefore, no inlet or outlet straight piping is required. These features make the DPM Series flow sensor ideal for mounting in locations where space is tight.

    • The Venturi Flowmeter with Magnehelic® Gage is fabricated from aluminum and has a gradual Venturi profile to reduce pressure losses through the meter. Flexible connections enable the meter to be used in vertical or horizontal applications. The Magnehelic® gage provides a large, clear and accurate display of your differential pressure reading. Each meter is calibrated at standard atmospheric conditions. The dual scale reads in SCFM and in w.c. The meter is supplied with easy to read reference charts for various flow conditions. It is available in line sizes from 1" to 4" and can handle vacuum and pressure applications.

    • The Series OP Orifice Plate Flowmeter is a complete orifice plate flow metering package. It incorporates a stainless steel orifice plate with a unique holder or carrier ring containing metering taps and integral gaskets. It was designed for use wherever there is an application for a conventional flow orifice plate. It can also be used in place of other primary differential producers for efficiency and cost effectiveness. Installation is accomplished simply by slipping the unit between standard flanges (orifice flanges are not required). The Series OP is available in line sizes from 1/2" to 24" and can be used with compatible liquids and gases.

    • The Heinrichs TMU Series high performance Coriolis mass flowmeter from KOBOLD Instruments distinguishes itself from the competition because we are able to achieve higher flow rates and mass flow measurements in larger line sizes than other mass flowmeter providers. With the TMU Series, we have achieved accurate mass flow measurements up to 2,200 metric tons per hour in line sizes up to 16 inches. It has a very accurate, rugged design built for mass flow measurements of liquids and gases in most chemical, petrochemical, oil and gas applications. Mass flow, density and temperature are simultaneously measured, and volumetric flow is computed from these parameters. The flowmeter’s wetted materials (fittings and measuring tubes) are available in 316L stainless steel or Hastelloy® C-22 with other materials available on request. There are no moving parts to wear out, and the measuring tubes and sensors are protected by a very rugged, all-welded housing. The TMU employs a highly effective measuring tube de-coupling system that virtually eliminates errors caused by piping-induced vibrations and stresses. This allows the flowmeter to provide very accurate mass flow measurements in the most demanding applications. The TMU Series high performance Coriolis mass flowmeter from KOBOLD Instruments is the clear choice if you require mass flow measurements of very high flows in large line sizes.

General Info

  • A bucket and a stopwatch is an analogy for the operation of a positive displacement meter the stopwatch is started when the flow starts, and stopped when the bucket reaches its limit. The volume divided by the time gives the flow rate. For continuous measurements, we need a system of continually filling and emptying buckets to divide the flow without letting it out of the pipe. These continuously forming and collapsing volumetric displacements may take the form of pistons reciprocating in cylinders, gear teeth mating against the internal wall of a meter or through a progressive cavity created by rotating oval gears or a helical screw.

  • This is similar to the single jet meter, except that the impeller is small with respect to the width of the pipe, and projects only partially into the flow, like the paddle wheel on a Mississippi riverboat.

  • Temperature at the sensors varies depending upon the mass flow Thermal mass flow meters generally use combinations of heated elements and temperature sensors to measure the difference between static and flowing heat transfer to a fluid and infer its flow with a knowledge of the fluid's specific heat and density. The fluid temperature is also measured and compensated for. If the density and specific heat characteristics of the fluid are constant, the meter can provide a direct mass flow readout, and does not need any additional pressure temperature compensation over their specified range. Technological progress has allowed the manufacture of thermal mass flow meters on a microscopic scale as MEMS sensors; these flow devices can be used to measure flow rates in the range of nanolitres or microlitres per minute. Thermal mass flow meter (also called thermal dispersion flow meter) technology is used for compressed air, nitrogen, helium, argon, oxygen, and natural gas. In fact, most gases can be measured as long as they are fairly clean and non-corrosive. For more aggressive gases, the meter may be made out of special alloys (e.g. Hastelloy), and pre-drying the gas also helps to minimize corrosion. Today, thermal mass flow meters are used to measure the flow of gases in a growing range of applications, such as chemical reactions or thermal transfer applications that are difficult for other flow metering technologies. This is because thermal mass flow meters monitor variations in one or more of the thermal characteristics (temperature, thermal conductivity, and/or specific heat) of gaseous media to define the mass flow rate.

  • The operation of thermal dispersion mass flow meters is attributed to L.V. King who, in 1914, published his famous King's Law revealing how a heated wire immersed in a fluid flow measures the mass velocity at a point in the flow. King called his instrument a "hot-wire anemometer". However, it was not until the 1960s and 1970s that industrial-grade thermal dispersion mass flow meters finally emerged.

  • Another method of flow measurement involves placing a bluff body (called a shedder bar) in the path of the fluid. As the fluid passes this bar, disturbances in the flow called vortices are created. The vortices trail behind the cylinder, alternatively from each side of the bluff body. This vortex trail is called the Von Kármán vortex street after von Kármán's 1912 mathematical description of the phenomenon. The frequency at which these vortices alternate sides is essentially proportional to the flow rate of the fluid. Inside, atop, or downstream of the shedder bar is a sensor for measuring the frequency of the vortex shedding. This sensor is often a piezoelectric crystal, which produces a small, but measurable, voltage pulse every time a vortex is created. Since the frequency of such a voltage pulse is also proportional to the fluid velocity, a volumetric flow rate is calculated using the cross sectional area of the flow meter. The frequency is measured and the flow rate is calculated by the flowmeter electronics using the equation where is the frequency of the vortices, the characteristic length of the bluff body, is the velocity of the flow over the bluff body, and is the Strouhal number, which is essentially a constant for a given body shape within its operating limits.

  • Modern innovations in the measurement of flow rate incorporate electronic devices that can correct for varying pressure and temperature (i.e. density) conditions, non-linearities, and for the characteristics of the fluid.

  • The variable area (VA) meter, also commonly called a rotameter, consists of a tapered tube, typically made of glass, with a float inside that is pushed up by fluid flow and pulled down by gravit\y. As flow rate increases, greater viscous and pressure forces on the float cause it to rise until it becomes stationary at a location in the tube that is wide enough for the forces to balance. Floats are made in many different shapes, with spheres and spherical ellipses being the most common. Some are designed to spin visibly in the fluid stream to aid the user in determining whether the float is stuck or not. Rotameters are available for a wide range of liquids but are most commonly used with water or air. They can be made to reliably measure flow down to 1% accuracy.

  • Liquid enters the precision metering insert containing the turbine rotor. The liquid pressure drives the turbine rotor rate of rotation proportional to the volumetric flow rate. The rotor's rotation is magnetically coupled to a hermetically sealed indicator or indicator/transmitter.

  • Ultrasonic transit time flow meters measure the difference of the transit time of ultrasonic pulses propagating in and against the direction of flow. This time difference is a measure for the average velocity of the fluid along the path of the ultrasonic beam. By using the absolute transit times both the averaged fluid velocity and the speed of sound can be calculated. Using the two transit times and and the distance between receiving and transmitting transducers and the inclination angle one can write the equations: and where is the average velocity of the fluid along the sound path and is the speed of sound. With wide-beam illumination transit time ultrasound can also be used to measure volume flow independent of the cross-sectional area of the vessel or tube.[11] Ultrasonic Doppler flow meters measure the Doppler shift resulting from reflecting an ultrasonic beam off the particulates in flowing fluid. The frequency of the transmitted beam is affected by the movement of the particles; this frequency shift can be used to calculate the fluid velocity. For the Doppler principle to work there must be a high enough density of sonically reflective materials such as solid particles or air bubbles suspended in the fluid. This is in direct contrast to an ultrasonic transit time flow meter, where bubbles and solid particles reduce the accuracy of the measurement. Due to the dependency on these particles there are limited applications for Doppler flow meters. This technology is also known as acoustic Doppler velocimetry. One advantage of ultrasonic flow meters is that they can effectively measure the flow rates for a wide variety of fluids, as long as the speed of sound through that fluid is known. For example, ultrasonic flow meters are used for the measurement of such diverse fluids a liquid natural gas (LNG) and blood.[12] One can also calculate the expected speed of sound for a given fluid; this can be compared to the speed of sound empirically measured by an ultrasonic flow meter for the purposes of monitoring the quality of the flow meter's measurements. A drop in quality (change in the measured speed of sound) is an indication that the meter needs servicing

  • Gases are compressible and change volume when placed under pressure, are heated or are cooled. A volume of gas under one set of pressure and temperature conditions is not equivalent to the same gas under different conditions. References will be made to "actual" flow rate through a meter and "standard" or "base" flow rate through a meter with units such as acm/h (actual cubic meters per hour), kscm/h (thousand standard cubic meters per hour), LFM (linear feet per minute), or MSCFD (million standard cubic feet per day). Gas mass flow rate can be directly measured, independent of pressure and temperature effects, with thermal mass flow meters, Coriolis mass flow meters, or mass flow controllers.

  • For liquids, various units are used depending upon the application and industry, but might include gallons (U.S. liquid or imperial) per minute, liters per second, bushels per minute or, when describing river flows, cumecs (cubic meters per second) or acre-feet per day. In oceanography a common unit to measure volume transport (volume of water transported by a current for example) is a sverdrup (Sv) equivalent to 106 m3 / s.

  • Magnetic flow meters, often called "mag meters” or "electromags”, use a magnetic field applied to the metering tube, which results in a potential difference proportional to the flow velocity perpendicular to the flux lines. The potential difference is sensed by electrodes aligned perpendicular to the flow and the applied magnetic field. The physical principle at work is Faraday's lawof electromagnetic induction. The magnetic flow meter requires a conducting fluid and a nonconducting pipe liner. The electrodes must not corrode in contact with the process fluid; some magnetic flow meters have auxiliary transducers installed to clean the electrodes in place. The applied magnetic field is pulsed, which allows the flow meter to cancel out the effect of stray voltage in the piping system.

  • Acoustic Doppler velocimetry (ADV) is designed to record instantaneous velocity components at a single point with a relatively high frequency. Measurements are performed by measuring the velocity of particles in a remote sampling volume based upon the Doppler shift effect.

  • Because they are used for domestic water measurement, piston meters, also known as rotary piston or semi-positive displacement meters, are the most common flow measurement devices in the UK and are used for almost all meter sizes up to and including 40 mm (1½ʺ). The piston meter operates on the principle of a piston rotating within a chamber of known volume. For each rotation, an amount of water passes through the piston chamber. Through a gear mechanism and, sometimes, a magnetic drive, a needle dial and odometer type display are advanced.

  • A propeller-type current meter as used for hydroelectric turbine testing. Flow through a large penstock such as used at a hydroelectric power plant can be measured by averaging the flow velocity over the entire area. Propeller-type current meters (similar to the purely mechanical Ekman current meter, but now with electronic data acquisition) can be traversed over the area of the penstock and velocities averaged to calculate total flow. This may be on the order of hundreds of cubic meters per second. The flow must be kept steady during the traverse of the current meters. Methods for testing hydroelectric turbines are given in IEC standard 41. Such flow measurements are often commercially important when testing the efficiency of large turbines.

  • An oval gear meter is a positive displacement meter that uses two or more oblong gears configured to rotate at right angles to one another, forming a T shape. Such a meter has two sides, which can be called A and B. No fluid passes through the center of the meter, where the teeth of the two gears always mesh. On one side of the meter (A), the teeth of the gears close off the fluid flow because the elongated gear on side A is protruding into the measurement chamber, while on the other side of the meter (B), a cavity holds a fixed volume of fluid in a measurement chamber. As the fluid pushes the gears, it rotates them, allowing the fluid in the measurement chamber on side B to be released into the outlet port. Meanwhile, fluid entering the inlet port will be driven into the measurement chamber of side a, which is now open. The teeth on side B will now close off the fluid from entering side B. This cycle continues as the gears rotate and fluid is metered through alternating measurement chambers. Permanent magnets in the rotating gears can transmit a signal to an electric reed switch or current transducer for flow measurement. Though claims for high performance are made, they are generally not as precise as the sliding vane design.

  • Helical gear flow meters get their name from the shape of their gears or rotors. These rotors resemble the shape of a helix, which is a spiral-shaped structure. As the fluid flows through the meter, it enters the compartments in the rotors, causing the rotors to rotate. Flow rate is calculated from the speed of rotation.

  • This is the most commonly used measurement system for measuring water supply in houses. The fluid, most commonly water, enters in one side of the meter and strikes the nutating disk, which is eccentrically mounted. The disk must then "wobble" or nutate about the vertical axis, since the bottom and the top of the disk remain in contact with the mounting chamber. A partition separates the inlet and outlet chambers. As the disk nutates, it gives direct indication of the volume of the liquid that has passed through the meter as volumetric flow is indicated by a gearing and register arrangement, which is connected to the disk. It is reliable for flow measurements within 1 percent.

  • The Woltmann meter comprises a rotor with helical blades inserted axially in the flow, much like a ducted fan; it can be considered a type of turbine flow meter. They are commonly referred to as helix meters, and are popular at larger sizes.

  • A single jet meter consists of a simple impeller with radial vanes, impinged upon by a single jet. They are increasing in popularity in the UK at larger sizes and are commonplace in the EU.

  • A multiple jet or multi-jet meter is a velocity type meter which has an impeller which rotates horizontally on a vertical shaft. The impeller element is in a housing in which multiple inlet ports direct the fluid flow at the impeller causing it to rotate in a specific direction in proportion to the flow velocity. This meter works mechanically much like a single jet meter except that the ports direct the flow at the impeller equally from several points around the circumference of the element, not just one point; this minimizes uneven wear on the impeller and its shaft.

  • The Pelton wheel turbine (better described as a radial turbine) translates the mechanical action of the Pelton wheel rotating in the liquid flow around an axis into a user-readable rate of flow (gpm, lpm, etc.). The Pelton wheel tends to have all the flow traveling around it with the inlet flow focused on the blades by a jet. The original Pelton wheels were used for the generation of power and consisted of a radial flow turbine with "reaction cups" which not only move with the force of the water on the face but return the flow in opposite direction using this change of fluid direction to further increase the efficiency of the turbine.

  • There are several types of flow meter that rely on Bernoulli's principle, either by measuring the differential pressure within a constriction, or by measuring static and stagnation pressures to derive the dynamic pressure.

  • A Venturi meter constricts the flow in some fashion, and pressure sensors measure the differential pressure before and within the constriction. This method is widely used to measure flow rate in the transmission of gas through pipelines, and has been used since Roman Empire times. The coefficient of discharge of Venturi meter ranges from 0.93 to 0.97. The first large-scale Venturi meters to measure liquid flows were developed by Clemens Herschel who used them to measure small and large flows of water and wastewater beginning at the end of the 19th century.

  • An orifice plate is a plate with a hole through it, placed in the flow; it constricts the flow, and measuring the pressure differential across the constriction gives the flow rate. It is basically a crude form of Venturi meter, but with higher energy losses. There are three type of orifice: concentric, eccentric, and segmental.

  • The Dall tube is a shortened version of a Venturi meter, with a lower pressure drop than an orifice plate. As with these flow meters the flow rate in a Dall tube is determined by measuring the pressure drop caused by restriction in the conduit. The pressure differential is typically measured using diaphragm pressure transducers with digital readout. Since these meters have significantly lower permanent pressure losses than orifice meters, Dall tubes are widely used for measuring the flow rate of large pipe works.

  • A Pitot tube is a pressure measuring instrument used to measure fluid flow velocity by determining the stagnation pressure. Bernoulli's equation is used to calculate the dynamic pressure and hence fluid velocity. Also see Air flow meter.

  • Multi-hole pressure probes (also called impact probes) extend the theory of pitot tube to more than one dimension. A typical impact probe consists of three or more holes (depending on the type of probe) on the measuring tip arranged in a specific pattern. More holes allow the instrument to measure the direction of the flow velocity in addition to its magnitude (after appropriate calibration). Three holes arranged in a line allow the pressure probes to measure the velocity vector in two dimensions. Introduction of more holes, e.g. five holes arranged in a "plus" formation, allow measurement of the three-dimensional velocity vector. Also see Annubar.

  • Cone meters are a newer differential pressure metering device first launched in 1985 by McCrometer in Hemet, CA. While working with the same basic principles as Ventrui and Orifice type DP meters, cone meters don’t require the same upstream and downstream piping. The cone acts as a conditioning device as well as a differential pressure producer. Upstream requirements are between 0-5 diameters compared to up to 44 diameters for an orifice plate or 22 diameters for a Venturi. Because cone meters are generally of welded construction, it is recommended they are always calibrated prior to service. Inevitably heat effects of welding cause distortions and other effects that prevent tabular data on discharge coefficients with respect to line size, beta ratio and operating Reynolds Numbers from being collected and published. Calibrated cone meters have an uncertainty up to +/-0.5%. Un-calibrated cone meters have an uncertainty of +/-5.0%.

  • Optical flow meters use light to determine flow rate. Small particles which accompany natural and industrial gases pass through two laser beams focused a short distance apart in the flow path. in a pipe by illuminating optics. Laser light is scattered when a particle crosses the first beam. The detecting optics collects scattered light on a photo detector, which then generates a pulse signal. As the same particle crosses the second beam, the detecting optics collect scattered light on a second photo detector, which converts the incoming light into a second electrical pulse. By measuring the time interval between these pulses, the gas velocity is calculated as where is the distance between the laser beams and is the time interval. Laser-based optical flow meters measure the actual speed of particles, a property which is not dependent on thermal conductivity of gases, variations in gas flow or composition of gases. The operating principle enables optical laser technology to deliver highly accurate flow data, even in challenging environments which may include high temperature, low flow rates, high pressure, high humidity, pipe vibration and acoustic noise. Optical flow meters are very stable with no moving parts and deliver a highly repeatable measurement over the life of the product. Because distance between the two laser sheets does not change, optical flow meters do not require periodic calibration after their initial commissioning. Optical flow meters require only one installation point, instead of the two installation points typically required by other types of meters. A single installation point is simpler, requires less maintenance and is less prone to errors. Commercially available optical flow meters are capable of measuring flow from 0.1 m/s to faster than 100 m/s (1000:1 turn down ratio) and have been demonstrated to be effective for the measurement of flare gases from oil wells and refineries, a contributor to atmospheric pollution.

  • The level of the water is measured at a designated point behind weir or in flume a hydraulic structure using various secondary devices (bubblers, ultrasonic, float, and differential pressure are common methods). This depth is converted to a flow rate according to a theoretical formula of the form where is the flow rate, is a constant, is the water level, and is an exponent which varies with the device used; or it is converted according to empirically derived level/flow data points (a "flow curve"). The flow rate can then integrated over time into volumetric flow. Level to flow devices are commonly used to measure the flow of surface waters (springs, stream, and rivers), industrial discharges, and sewage. Of these, weirs are used on flow streams with low solids (typically surface waters), while flumes are used on flows containing low or high solids contents. The cross-sectional area of the flow is calculated from a depth measurement and the average velocity of the flow is measured directly (Doppler and propeller methods are common). Velocity times the cross-sectional area yields a flow rate which can be integrated into volumetric flow. A known amount of dye (or salt) per unit time is added to a flow stream. After complete mixing, the concentration is measured. The dilution rate equals the flow rates.

  • A Lorentz force velocimetry system is called Lorentz force flow meter (LFF). A LFF measures the integrated or bulk Lorentz force resulting from the interaction between a liquid metal in motion and an applied magnetic field. In this case the characteristic length of the magnetic field is of the same order of magnitude as the dimensions of the channel. It must be addressed that in the case where localized magnetic fields are used, it is possible to perform local velocity measurements and thus the term Lorentz force velocimeter is used.

  • Ultrasonic transit time flow meters measure the difference of the transit time of ultrasonic pulses propagating in and against the direction of flow. This time difference is a measure for the average velocity of the fluid along the path of the ultrasonic beam. By using the absolute transit times both the averaged fluid velocity and the speed of sound can be calculated. Using the two transit times and and the distance between receiving and transmitting transducers and the inclination angle one can write the equations: and where is the average velocity of the fluid along the sound path and is the speed of sound. With wide-beam illumination transit time ultrasound can also be used to measure volume flow independent of the cross-sectional area of the vessel or tube.[11] Ultrasonic Doppler flow meters measure the Doppler shift resulting from reflecting an ultrasonic beam off the particulates in flowing fluid. The frequency of the transmitted beam is affected by the movement of the particles; this frequency shift can be used to calculate the fluid velocity. For the Doppler principle to work there must be a high enough density of sonically reflective materials such as solid particles or air bubbles suspended in the fluid. This is in direct contrast to an ultrasonic transit time flow meter, where bubbles and solid particles reduce the accuracy of the measurement. Due to the dependency on these particles there are limited applications for Doppler flow meters. This technology is also known as acoustic Doppler velocimetry. One advantage of ultrasonic flow meters is that they can effectively measure the flow rates for a wide variety of fluids, as long as the speed of sound through that fluid is known. For example, ultrasonic flow meters are used for the measurement of such diverse fluids a liquid natural gas (LNG) and blood.[12] One can also calculate the expected speed of sound for a given fluid; this can be compared to the speed of sound empirically measured by an ultrasonic flow meter for the purposes of monitoring the quality of the flow meter's measurements. A drop in quality (change in the measured speed of sound) is an indication that the meter needs servicing.

  • Using the Coriolis effect that causes a laterally vibrating tube to distort, a direct measurement of mass flow can be obtained in a coriolis flow meter. Furthermore a direct measure of the density of the fluid is obtained. Coriolis measurement can be very accurate irrespective of the type of gas or liquid that is measured; the same measurement tube can be used for hydrogen gas and bitumen without recalibration. Coriolis flow meters can be used for the measurement of natural gas flow.

  • Even though ideally the flowmeter should be unaffected by its environment, in practice this is unlikely to be the case. Often measurement errors originate from incorrect installation or other environment dependent factors. In situ methods are used when flow meter is calibrated in the correct flow conditions.

  • For pipe flows a so-called transit time method is applied where a radiotracer is injected as a pulse into the measured flow. The transit time is defined with the help of radiation detectors placed on the outside of the pipe. The volume flow is obtained by multiplying the measured average fluid flow velocity by the inner pipe cross section. This reference flow value is compared with the simultaneous flow value given by the flow measurement to be calibrated. The procedure is standardized (ISO 2975/VII for liquids and BS 5857-2.4 for gases). The best accredited measurement uncertainty for liquids and gases is 0.5%.

  • The radiotracer dilution method is used to calibrate open channel flow measurements. A solution with a known tracer concentration is injected at a constant known velocity into the channel flow. Downstream where the tracer solution is thoroughly mixed over the flow cross section, a continuous sample is taken and its tracer concentration in relation to that of the injected solution is determined. The flow reference value is determined by using the tracer balance condition between the injected tracer flow and the diluting flow.. The procedure is standardized (ISO 9555-1 and ISO 9555-2 for liquid flow in open channels). The best accredited measurement uncertainty is 1% W.H. Cooke & Co. has on-site flow calibration technicians that we work with and we can send someone out to your plant to evaluate your needs and provide you with a quote. If you have a flow application that we can assist with, please dowload the pdf below, fill in as much information as possible and email us at sales@whcooke.com or call (717) 630-2222 and we will be happy to assist you.