Flow Meters
Litre-counter for water and volumetric, electromagnetic, mass and ultrasonic flow meters and sensors.
The sectors in which a flow meter is required are many and vary from the food industry where precise, reliable and complete flow meters with food certification and metric certification for fiscal use are required, such as an electromagnetic flow meter or a mass flow meter, to the chemical and petrochemical and paper industries, where Riels® Instruments offers an ATEX certified flowmeter with oval wheels or magnetic flowmeter and ultrasonic flowmeter.
Another sector of considerable importance is that of aqueducts which requires volumetric water meters and magnetic flow meters to be combined with data recorders for monitoring consumption.
Below we indicate, according to the different measurement principles, the available flow meters:
The flow rate expresses the quantity of fluid (liquid, gas or steam) that passes through a section in the unit of time. It can be expressed in volume terms (m3/h, l/min, l/h, etc.) or in mass terms (kg/s, Kg/h, etc.).
The main factor for flow measurement is the average outflow velocity, from which the Reynolds number (Re) is obtained, which divides the fluid motion into two categories: laminar (typically with Re < 2000) and turbulent (typically with King > 10000).
- Electromagnetic flow meter
- Volumetric flow meters (oval wheel meters, oscillating piston meters, nutating disc meters)
- Turbine flow meter
- Vortex flowmeter
- Mass or Coriolis flow meter
- Ultrasonic flow meter
- Open channel flow meter
- Thermal dispersion flow meter
Electromagnetic flow meters are based on Faraday's law of magnetic induction, which states that a conductor (which is the liquid itself) immersed in a magnetic field produces at its ends an electromotive force proportional to the speed with which the conductor cuts the lines of magnetic field flux.
These are particularly indicated when you want to have a precise and accurate measurement. Since the magnetic flow meter is an empty pipe, it is suitable for dirty liquids and with suspended solids, or for food liquids.
The necessary conditions for the correct functioning of the electromagnetic flowmeter are: full pipe and electrically conductive liquid.
Volumetric flow meters determine the flow based on geometric volumes generated and counted by the measuring device. Volumetric flow meters are made up of a mobile element which can be a disc, a piston or a pair of gears, which under the pressure of the liquid set in motion a transmission shaft which transfers the movement of the mobile element to the outside of the body where it is collected by a counting device.
Volumetric flow meters are used for custody transfer measures due to their high precision and are suitable for high viscosity liquids such as refined petroleum products such as diesel, petrol, fuel oil, kerosene, naphtha, LPG and solvents. One of the main disadvantages of the volumetric flowmeter is the deterioration of the mobile measuring device and this makes it unsuitable for use with dirty or abrasive liquids.
Turbine flow meters consist of a very light impeller, consisting of a propeller or a whirlpool, which detects the speed of a fluid current and transforms it into rotary motion, the speed of which is a function of the flowing flow rate.
Turbine flow meters are suitable for industrial measurements of gases and liquids and are applied in turbulent conditions (Re>10000). A turbine flowmeter is not suitable for high viscosity fluids, the impeller is subject to deterioration and it is necessary to filter the fluid to prevent suspended solids present in the fluid from damaging the instrument.
The turbine flow meter is suitable for gases such as methane, nitrogen, air, hydrogen, etc., and fluids such as water and neutral fluids.
Vortex flow meters are based on Karman's law which studied and codified the formation of vortexes of fluids in motion. The vortices are caused by a suitable shaped body installed in the pipe; it is therefore a phenomenon generated by the fluid itself and is theoretically linear with the velocity of the fluid in a turbulent flow regime (Re>10000).
The Vortex flow meter is suitable for both liquids and gases in pipes of limited dimensions and is not suitable for viscous fluids for which fluid filtration is required.
Mass flow meters exploit the Coriolis effect which occurs when a fluid flows in a rotating system. Mass flow meters, therefore, are not affected by changes in the physical parameters of the fluid such as temperature, pressure, density and viscosity.
The mass flow meter consists of a U-tube, which instead of being rotated, is periodically oscillated at the resonant frequency.
A microprocessor maintains the mass flow meter in vibration and detects and processes the signals coming from the sensors.
Coriolis flow meters can be used regardless of the nature of the fluid, as long as it is compressed in the case of gas.
Ultrasonic flow meters exploit the ability of materials to propagate sound, in fluids in particular the speed of sound propagation is a characteristic that depends on the density, pressure and temperature. Ultrasonic flow meters work according to the following principle: an electric impulse is applied to an electroacoustic transducer which transforms it into a corresponding sonic energy impulse with a frequency between 0.5 and 5 MHz. The impulse propagates in the fluid under test, with speed depending on the speed of the fluid itself, up to the receiver where it is transformed into an electrical signal.
The ultrasonic flow meter can also be used for dirty or abrasive fluids and for large diameter pipes, however its accuracy is influenced by the fluid regime.
Open channel flow meters are applied where there is no pipeline but an open conduit (channel). In open channel flow meters the level measurement takes place in the narrow section where the flow increases in speed. The maximum admissible speed varies according to the dimensions of the channel from about 0.5m/s to 2m/s.
Open channel flow meters are typically employed in “free flow” conditions with the flowing water level low enough not to exert back pressure against the high velocity jet passing through the restricted section of channel.
An open channel flow meter can be used for medium and large flow rates even with dirty fluids or those with suspended solids.
Thermal dispersion flow meters are based on the principle of heat transfer according to which the measured flow flowing in a pipe is subjected, via a heating resistance crossed by an electric current, to a heating power which will be absorbed by the fluid. The thermal dispersion flow meters can be insertion with internal or external heating of the pipe or of the derivation type for small, medium and large pipes. The latter consist of a capillary tube (suitably heated and measured) into which a part of the flowing flow is pushed through a laminar measuring device placed in the outflow pipe.
The thermal dispersion flowmeter is mainly applied for gases but the thermo-physical properties of the fluid must be known.
All the flow meters that Riels Instruments is able to offer, with the exception of the volumetric and mass flow meters, are punctual or average velocity meters of the flow and therefore are sensitive to the velocity distribution in the measurement section, a distribution which changes with the number of Reynolds and therefore with the operating conditions.
Riels Instruments is an established company in the field of measurement and control of industrial processes. Among the numerous products offered by Riels Instruments, we highlight the water meters or litre-counters and the gas meters. These items are used in different fields but have the same function, i.e. to quantify water and gas consumption. In this regard, Riels Instruments offers gas meters and water meters certified for tax use and therefore provided with a metric verification sticker beforehand.
The meters for gas and biogas normally offered are volumetric turbine meters; however, Riels Instruments is able to offer more technologically advanced solutions such as massive coriolis meters and ultrasonic flow meters for gases. In some applications, the differential pressure transmitter coupled to a calibrated flange can be supplied.
Our company has occupied an extremely important position for more than forty years, and has developed great professionalism, also gaining vast experience in the field of flow but also in the field of level, pressure, flow, temperature and humidity measurement. We therefore offer first quality products and services.
The sector of meters or liter meters for water has developed a lot in recent years thanks also and above all to the new technologies used for remote management of process data.
Water meters range from gear volumetric meters to electromagnetic flow meters. The fields of application are many, from the aqueduct sector, where continuous monitoring and recording of flow rate values and daily consumption is required, to the food sector with problems relating to the precise dosage of fluids. Water meters and gas meters are available in different diameters and with different ranges according to the flow rates of the systems.
Contact Riels® Instruments now! You will have information, clarifications and sizing on all the products and on the water and gas meters that are best suited to your needs.
Our technicians will also inform you about the operation and typical applications of each product!
