If the amount of suspended solids exceeds 100 mg/l of +75 micron size, a flushing y-strainer or a motorized cartridge filter must be installed at least 20 diameters of straight run upstream of the flow meter. ), ( They are suited for 150-psig operating pressures with overpressure to a maximum of 300 psig. Under lower pressure conditions, typical rangeability is 20:1 with ±1% linearity. Instead of pick-up coils, Hall-effect transistors also can be used. Rotating vane meters (Figure 3-1B) have spring-loaded vanes that entrap increments of liquid between the eccentrically mounted rotor and the casing. This type of metering pump is used in laboratories, in a variety of medical applications, in the majority of environmental sampling systems, and also in dispensing hypochlorite solutions. Optical or magnetic sensors are used to encode a pulse train proportional to the rotational speed of the helical gears. Flow Meters. Showing units in {{labelText}} Switch … ), ( In order to reduce this straight-run requirement, straightening vanes are installed. ), ( Capacitive sensors produce a sine wave by generating an RF signal that is amplitude-modulated by the movement of the rotor blades. 10 Figure 3-4: Click on figure to enlarge. This compensation is obtained by very large rotor hubs, very light rotor assemblies, and larger numbers of rotor blades. On the register side, an opposing magnet is mounted to turn the gear. 1″ Digital Turbine Flow Meter,Gas Oil Fuel Flowmeter,Pump Flow Meter ,Diesel Fuel Flow Meter,High Accuracy,for Measure Diesel, Kerosene, Gasoline, etc. Higher accuracy can be achieved by calibrating the meter and by lowering its range. The turbine is suspended by a bearing between two hanger assemblies that also serve to condition the flow. Provers are available for bench-top use, for mounting in truck-beds, on trailers, or in-line. Mechanical Flowmeter Rs 1,000/ Piece Get Latest Price We are a well established name engaged in offering variety of Mechanical Meter to fulfill the needs of our clients. This magnet is coupled to a mechanical register or a pulse transmitter. Mechanical Flow meters Published April 17, 2019 Discussed in this chapter are various types of mechanical flow meters that measure flow using an arrangement of moving parts, either by … The internals of this flow meter can be removed without disconnection of the meter from the pipeline. The accuracy of these meters is required to be ±2% of actual flow rate. thick fluids such as glues and very viscous polymers. If the process fluid has good lubricating characteristics, the meter turndown can be as high as 100:1, but lower (10:1) turndowns are more typical. The turbine flow meter consists of a multi-bladed rotor mounted at right angles to the flow, suspended in the fluid stream on a free-running bearing. 9 ), ( These meters are used to meter paints and, because they are available in 3A or sanitary designs, also milk, juices, and chocolate. Figure 3-9 shows a typical turbine-meter calibration curve describing the relationship between flow and K-factor (pulses/gallon). As the bell is lowered, it discharges a known volume of gas through the meter being tested. 32 overflow:hidden; If the process fluid viscosity is greater than 10 centipoise and the flowrate is above 20% of rated capacity, accuracy of 0.1% AR can be obtained. As each blade passes the coil, it generates a voltage pulse. Barstock turbine meters typically are linear to ±0.25% AR over a 10:1 flow range. ), ( well as operating the crank mechanism for the meter register. Liquid systems can be calibrated in the laboratory against either a calibrated secondary standard or a gravimetric flow loop. Turbine meters have a typical nonlinearity (the turbine meter hump, shown in Figure 3-9) in the lower 25-30% of their range. As the flow passes through the chamber, the displacer piston is moved downstream. }, Copyright 2003 - 2019 OMEGA Engineering is a subsidiary of Spectris plc. Flow capacity is 8-10 gpm to 18,000 gpm in the larger sizes. Totalizers measure the cumulative flow volume. Several manufacturers, however, use crooked rotors that only rotate in the forward direction. Shunt flow meters are used in gas and steam service. Specifications call for 10-15 diameters of straight run upstream and five diameters of straight run downstream of the meter. View Detail. Accuracy ranges from ±0.5 % AR for viscous fluids to ±2% AR for nonviscous applications. The resulting K-factor in pulses per volume unit will vary within the stated linearity specification. Figure 3-10: Click on figure to enlarge. Because there are minor inconsistencies in the manufacturing process, all turbine flow meters are calibrated prior to shipment. Each meter applies to different applications. It consists of a multi-bladed rotor mounted at right angles to the flow and suspended in the fluid stream on a free-running bearing. Accuracy of ±0.1% of actual rate (AR) is normal, and larger size meters on higher viscosity services can achieve accuracy to within 0.05% of rate. Automatic meter reading (AMR) devices permit the remote retrieval of readings by utility personnel. Turbine rotation can be detected by solid state devices or by mechanical sensors. Because Hall-effect sensors have no magnetic drag, they can operate at lower flow velocities (0.2 ft/sec) than magnetic pick-up designs (0.5-1.0 ft/sec). The helix meter is a positive displacement device that uses two radially pitched helical gears to continuously entrap the process fluid as it flows. Choose from our many different types of … The signal output from a Hall-effect sensor is a square wave pulse train, at a frequency proportional to the volumetric flowrate. The outputs of reluctance and inductive pick-up coils are continuous sine waves with the pulse train's frequency proportional to the flow rate. They are often used in large diameter pipelines where it would be cost-prohibitive to install a full size meter. The first causes the meter to read high, the second results in rotor damage. That comprises volumetric meters like diaphragm meters … This design is suited for high operating pressures (up to 5,000 psig). proportional to the volumetric flow rate. These meters also can be used on residential water service and can pass limited quantities of dirt, such as pipe scale and fine (viz,-200 mesh or -74 micron) sand, but not large particle size or abrasive solids. ), ( In the rotating lobe design, two impellers rotate in opposite directions within the ovoid housing (Figure 3-3B). This increases accuracy at low flows and under varying viscosity conditions (Figure 3-6B). Ultrasonic Bulk Water Meters. ), ( The meter is constructed from aluminum castings with cloth-backed rubber diaphragms. The shaft passes between the metering tube and the register section through a mechanical stuff ), ( Pressure and temperature limits depend on the materials of construction and can be as high as 350°F and 1,000 psig. The two rotors turn in opposite directions. It is designed to be inserted into either a liquid or a gas line to a depth at which the small-diameter rotor will read the average velocity in the line. ), ( The repeatability is from ±0.2% to ±0.02% over the linear range. Flow Meters and Environmental Sensors for Precision Fluid Measurement. Viscosity limits are 1 to 25,000 centipoise. They are also simple and inexpensive, keeping costs low. Totalizers measure the cumulative flow volume. Whether functioning through a relay contact or a ramp function, these features serve to minimize splashing or overfill and to accurately terminate the batch. Propeller meters are commonly used in large diameter (over 4 in) irrigation and water distribution systems. The number of pulses per unit volume is called the meter's K-factor. Keeping the minimum flow reading above this region will permit linearity to within 0.15% on small and 0.25% on larger turbine meters. Because the flow meter entraps a fixed quantity of fluid each time the spindle is rotated, the rate of flow is proportional to the rotational velocity of the spindle (Figure 3-1A). If the range of 10:1 is insufficient, some turbine flow- meters can provide up to 100:1 turndowns if accuracy is de-rated to 1% of full scale (FS). Lobe meters can be furnished in 2-in to 24-in line sizes. Class I turbine meters must register between 98-102% of actual rate at maximum flow when tested. In these turbine flow meters, very small magnets are embedded in the tips of the rotor blades. For liquid service, a servomotor-driven oval-gear meter equalizes the pressure across the meter. They are the most common and economical type of water flow meters which perform flow measurement through turbine rotation with a shunt, propeller, or paddle wheel design. The batching controller is set with the desired target volume and, when its totalizer has counted down to zero, it terminates the batch. It is now possible to include complex linearization functions in the preamplifier of a turbine flow meter to reduce these nonlinearities. Because at maximum flow the pressure drop through the meter should not exceed 30 psid, the maximum rated flow through the meter is reduced as the fluid viscosity increases. They can be hot-tapped into existing The calibration for the new flow rating (QN) is obtained by multiplying the meter's flow rating for natural gas (QC) by the square root of the ratio of the specific gravities of natural gas (0.6) and the new gas (SGN): High-precision gas meters are usually a hybrid combining a standard PD meter and a motor drive that eliminates the pressure drop across the meter. The piston is also cylindrical and is punctured by numerous openings to allow free flow on both sides of the piston and the post (Figure 3-2A). In industrial applications, however, these meters are likely to pass this threshold much sooner. The piston is guided by a control roller within the measuring chamber, and the motion of the piston is transferred to a follower magnet which is external to the flowstream. ), ( With liquids that do not lubricate well, maximum rotor speed must be derated to limit wear. The motion of the piston is oscillatory (not rotary) since it is constrained to move in one plane. pipelines (6 in or larger) through a valving system without shutting down the process. 20 diameters for 90° elbow, tee, filter, strainer, or thermowell; In addition, the Hall-effect sensor provides a signal of high amplitude (typically a 10.8-V square wave), permitting distances up to 3,000 ft. between the sensor and the electronics without amplification. 5 The maximum continuous flow of a nutating disc meter is usually about 60-80% of the maximum flow in intermittent service. The accuracy of turbine meters is typically given in percentage of actual rate (% AR). Mechanical Flowmeter Flowmeters 396 products A liquid flow meter from Grainger can help easily monitor liquid flow rates for water, fuels, viscous fluids and more. While PD meters are operated by the kinetic energy of the flowing fluid, metering pumps (described only briefly in this article) determine the flow rate while also adding kinetic energy to the fluid. The meter consists of four chambers: the two diaphragm chambers on the inlet and outlet sides and the inlet and outlet chambers of the meter body. 1 Water Meters Water Meters are sensors that indicate flow totalization of water. 12 range 10cm/sec (1/5 knot) to 7.9m/sec approximately (15 knots) The most common mechanical flow meters are inserted into a pipe and use a turbine, wheel or paddle to measure velocity and then calculate volumetric flow by knowing the cross section … Flow ranges from 0.04-40 gph are typical. On low density fluids (SG < 0.7), the minimum flow rate is increased due to the reduced torque, but the meter's accuracy usually is not affected. They are used as residential water meters around the world. The diameter of the rotor is very close to the inside diameter of the metering chamber, and its speed of rotation is proportional to the volumetric flow rate. in the coil (Figure 3-8A). Because of the small size of the jet orifice, these meters can only be used on clean fluids and they incur a pressure drop of about 20 psid. These turbine meters use a gear train to convert the rotation of the rotor into the rotation of a vertical shaft. These meters can be made out of a variety of metals, including stainless steel, and corrosion-resistant plastics such as PVDF (Kynar). In the United States, the AWWA sets the standards for turbine flow meters used in water distribution systems. whereas turbine meters intended for municipal water service are bronze or cast iron. For paddle wheel flow meters the wheel blades are smaller in width compared to single jet flow meter and are only partially projected in the path of the flow. The rate of flow is proportional to the rate of oscillation of the piston. Variable Area Meters Provide precise visual indication of rates of flow of air, liquids and industrial gases. .top-level { Gas systems are recalibrated against a bell-jar prover--a calibrated cylindrical bell, liquid sealed in a tank. As shown in Figure 3-4, measurement error rises as either the operating flowrate or the viscosity of the process fluid drops. Tube bundles or radial vane elements are used as external flow straighteners located at least 5 diameters upstream of the meter (Figure 3-10). As with all positive displacement pumps, piston pumps generate a pulsating flow. The volumetric accuracy of bell-jar provers is on the order of 0.1% by volume, and provers are available in discharge volumes of 2, 5, 10 ft3 and larger. Rotating vane meters are regularly For smaller pipes (1/2" to 3"), these meters are available only with a fixed insertion depth, while for larger pipe sizes (4" to 48") adjustable insertion depths are available. These transistors change their state when they are in the presence of a very low strength (on the order of 25 gauss) magnetic field. By counting the number of passed isolated volumes, a flow measurement is obtained. Because they are very sensitive to the velocity profile of the flowing stream, they must be profiled at several points across the flow path. Industrial Magmeters; Irrigation Magmeters Generally, turbine meters perform well if the Reynolds Number is greater than 4,000 and less than or equal to 20,000. Two detectors are mounted a known distance (and therefore a known volume) apart. Higher viscosity can produce higher accuracy, while lower viscosity and wear over time will reduce accuracy. These Fuel Meter are exceptionally intended to quantify quick … They can meter flow rates from 1 gpm to 65 gpm in continuous service with intermittent excursions to 100 gpm. Errors were found with the address you provided. Solid state pickup designs are less susceptible to mechanical wear than AWWA Class I and Class II meters. The lobe gear meter is available in a wide range of materials of construction, from thermoplastics to highly corrosion-resistant metals. AWWA Standard C-704 sets the accuracy criterion for propeller meters at 2% of reading. The AWWA requires that residential water meters be re-calibrated every 10 years. The impeller is either geared to a register or is magnetically coupled to a transmitter. 2 High precision flow meters are used on engine test stands for fuel flow measurement (gasoline, diesel, alcohol, etc.). Repeatability is generally not greatly affected by changes in viscosity, and turbine meters often are used to control the flow of viscous fluids. Another way to limit wear is to keep the pressure drop across the meter below 15 psid. Figure 3-6: Click on figure to enlarge. In all cases, bearings and shafts are designed to provide minimum friction and maximum resistance to wear. Materials of construction include polypropylene, PVDF, TFE and PFA, brass, aluminum, and stainless steel. Series Body Material Conn. All Rights Reserved. Standard Mechanical Flowmeters Basic vane-operated flowmeters provide inexpensive flow monitoring for processing and troubleshooting. Mechanical registers can be equipped with mechanical or electronic ticket-printers for inventory control and point-of-use sales. Standard C701 provides for two classes (Class I and Class II) of turbine flow meters. In the reluctance pick-up, the coil is a permanent magnet and the turbine blades are made of a material attracted to magnets. Its applications and features are similar to those of the rotary vane meter. Find a Distributor Contact Us 800-975-8153 . This action alternately empties and fills the four chambers. These meters can be very accurate if slippage between the housing and the gears is kept small. Mechanical Flow Meters. The diameter of the rotor is very slightly less than the inside diameter of the metering chamber, and its speed of rotation is proportional to the volumetric flow rate. The piston can either be directly coupled to the diaphragm or can force a hydraulic oil to drive the diaphragm. } Each PD design uses a different means of isolating and counting these volumes. Flow computers are capable of linearization, automatic temperature compensation, batching, calculation of BTU content, datalogging, and storage of multiple K-factors. Mechanical Water Flow Meters. The frequency of the resulting pulse train is a measure of flow rate, while the total number of pulses gives the size of the batch. Insertion turbine meters can be designed for gas applications (small, lightweight rotor) or for liquid (larger rotor, water-lubricated bearings). Density changes do not greatly affect turbine meters. Flow velocities under 1 ft/sec can be insufficient, while velocities in excess of 10 ft/sec can result in excessive wear. Rotameters are flow meters that measure the volumetric flow rate of liquid in a closed plastic or glass tube. However, the presence of any of the following obstructions upstream would necessitate that there be more than 15 diameters of upstream straight-pipe runs PD meter accessories include strainers, filters, air/vapor release assemblies, pulsation dampeners, temperature compensation systems, and a variety of valves to permit dribble cut-off in batching systems. Introduction to Venturi meters and tubes, @media screen and (max-width:1024px){ In addition, advances in fieldbus technology make it possible to recalibrate turbine flow meters continuously, thereby correcting for changes in temperature and viscosity. The volumetric flow rate of the water is proportional to the rotational speed of the blades. The turbine meter's operating temperature ranges from -200 to 450°C (-328 to 840°F). The rotation of the vanes moves the flow increment from inlet to outlet and discharge. (Blue) 3.3 out of 5 stars 27. Turbine meters are sensitive to upstream piping geometry that can cause vortices and swirling flow. The tubing can be silicone-rubber or, if a more corrosion-resistant material is desired, PTFE tubing. AIR / GAS FLOW METERS ; FLOW … It is possible, however, to register several K-factors for different portions of the flow range and to electronically switch from one to the other as the measured flow changes. As they rotate, a fixed volume of liquid is entrapped and then transported toward the outlet. Mechanical wear, straightening, and conditioning requirements are the same as for turbine meters. It is therefore important to calibrate the meter for the specific fluid it is intended to measure. Most industrial turbine flow meters are manufactured from austenitic stainless steel (301, 303, 304SS), Please verify your address. Accuracy is not affected by pulsating flow unless it entrains air or gas in the fluid. Class II turbine meters must register between 98.5-101.5% of actual rate. Batching flow computers are readily available, as are analog and intelligent digital transmitters. 11 As water flows through the metering chamber, it causes a disc to wobble (nutate), turning a spindle, which rotates a magnet. and larger and are accurate to ±2% over a range of 10:1. As each blade passes the coil, a voltage is generated Piston pumps are sized on the basis of the displacement of the piston and the required flow rate and discharge pressure. Most propeller meters are equipped with mechanical registers. Gas meters compensate for the lower driving torque produced by the relatively low density of gases. All meters with moving parts require periodic testing, recalibration and repair, because wear increases the clearances. This particular meter has a linearity tolerance band of ±0.25% over a 10:1 flow range and a ±0.15% linearity in a 6:1 range. More recently, the water distribution industry has adopted a magnetic drive as an improvement over high maintenance mechanical-drive turbine meters. The use of capacitively coupled pick-ups or Hall-effect sensors extends the range of paddlewheel meters into the low-flow velocity region of 0.3 ft/sec. Nutating disc meters are available in 5/8-in to 2-in sizes. These meters are accurate to 0.5% of rate if the viscosity of the process fluid is both high and constant, or varies only within a narrow band. In many operations, especially in the petroleum industry, it is difficult or impossible to remove a flow- meter from service for calibration. In high-precision gas flow meter installations, high-sensitivity leaves are used to detect the pressure differential, and displacement transducers are used to measure the deflection of the leaves (Figure 3-6A). 15 Provers are repeatable on the order of 0.02%, and can operate at up to 3,000 psig and 165°F/75°C. Piston pumps deliver a fixed volume of liquid with each "out" stroke and a fixed volume enters the chamber on each "in" stroke (Figure 3-5A). Upper limit on viscosity is 10,000 centipoise. Available are local and remote inidication models. Dwyer water meters … Because pressure drop increases with the square of flow rate, reducing the meter to the next smaller size will raise the pressure drop considerably. Meters are sized so that pressure drop is below 35 psid at maximum flow rate. Flowmeters measure the rate of flow for a liquid or a gas. 3.4 out of 5 stars 22. This design is claimed to provide 0.25% of rate accuracy over a 50:1 range at operating pressures of up to 150 psig. Such packages are equipped with dribble flow, pre-warn, or trickle-cut-off circuits. In the inductance pick-up, the permanent magnet is embedded in the rotor, or the blades of the rotor are made of permanently magnetized material (Figure 3-8B). Other types of rotary element flow meters include propeller (impeller), shunt, and paddlewheel designs. Flowmeter/totalizers display both the flow rate and the cumulative flow volume. Small turbine meters often are called barstock turbines because in sizes of 3/4 in to 3 in. Turbine meters also can be damaged by solids entrained in the fluid. Because of the intermittent use patterns of residential users, this corresponds to recalibrating 5/8 x 3/4 in residential water meters after they have metered 5 million gallons. Dwyer's multi-jet models are economical and dry dials. Because it must be nonmagnetic, the meter housing is usually made of bronze but can be made from plastic for corrosion resistance or cost savings. Digital Turbine Flow Meter,1″ Digital LCD Display with NPT Counter Gas Oil Fuel Flowmeter,Pump Flow Meter,Diesel Fuel Flow Meter for Measure Diesel, Kerosene, Gasoline. 50 or more diameters if there are two elbows in different planes or if the flow is spiraling or corkscrewing. In the water distribution industry, mechanical-drive Woltman-type turbine flow meters continue to be the standard. ), Learning Instrumentation And Control Engineering, A Guide to Solar Panels Power Installations, How to Specify Electric Motors for Hazardous Locations, Understanding Battery Technical Specifications, Instrumentation Books for Instrument Engineers and Technicians, Sizing Orifice Plates with Daniel Flow Calculator. flowmeter, digital, mechanical, w/standard rotor response with the standard rotor-threshold approximately 10cm/sec (1/5 knot). ambient temperatures and at up to 30 psig pressures, this meter is claimed to provide accuracy to within 0.25% of reading over a 50:1 range and 0.5% over a 100:1 range. The flow forces the helical gears to rotate in the plane of the pipeline. They consist of an orifice in the main line and a rotor assembly in the bypass. Small amounts of air entrainment (100 mg/l or less) will make the meter read only a bit high, while large quantities can destroy the rotor. Products. Naturally, the K-factor is applicable only to the fluid for which the meter was calibrated.

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