|
Flow measurement is the quantification of bulk fluid or gas movement. It can be measured in a variety of ways. A subset of the phases of matter, fluids include liquids, gases, plasmas and, to some extent, plastic solids. ...
A gas is one of the four main phases of matter (after solid and liquid, and followed by plasma), that subsequently appear as a solid material is subjected to increasingly higher temperatures. ...
Dependent on the quantity measured different symbols are used. The volumetric flow rate is usually given the symbol Q and the mass flow rate the symbol . In fluid dynamics, the volumetric flow rate, also volume flow rate and rate of fluid flow, is the volume of fluid which passes through a given area per unit time. ...
Mass flow rate is the movement of mass per time. ...
Units of measurement
Volumetric flow rate is sometimes measured in "standard cubic centimeters per minute" (abbreviation sccm), a unit acceptable for use with SI except that the additional information attached to the unit symbol. The SI standard would be m3/s (with any appropriate prefix, with temperature and pressure specified. The term "standard" indicates that the given flow rate assumes a standard temperature and pressure. Many other similar abbreviations are also in use, such as standard cubic feet per minute or per second. Other units used include gallons (U.S. liquid or imperial) per minute, liters per second, bushels per minute, and acre-feet per day. Cover of brochure The International System of Units. ...
Temperature and air pressure can vary from one place to another on the Earth, and can also vary in the same place with time. ...
Mechanical flow meters There are three main types of mechanical meter:-
>Piston Meter >Woltmann Meter >Jet Meter.
Piston meters, or Semi-Positive displacement meters are the most common in the UK and are used for almost all meter sizes up to and including 40mm (1 1/2"). The piston meter operates on the principle of a piston rotating within a chamber of known volume. For each rotation, an amount of water passed through the piston chamber.
Woltman meters, commonly referred to as Helix meters are popular at larger sizes. Jet meters (single or Multi-Jet) are increasing in popularity in the UK at larger sizes and are commonplace in the EU, largely due to the inferior quality of drinking water compared to the UK.
Another method of measurement, known as a venturi meter, is to constrict the flow in some fashion, and measure the differential pressure that results across 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. A fluid passing through smoothly varying constrictions experience changes in velocity and pressure, as described by Bernoullis principle. ...
For other senses of this name, see Roman Empire (disambiguation). ...
Another simple method of measurement uses an orifice plate, which is basically a plate with a hole through it. It is placed in the flow and constricts the flow. It uses the same principle as the venturi meter in that the differential pressure relates to the velocity of the fluid flow (Bernoulli's equation). An orifice plate is a device which measures rate of fluid flow. ...
A variation on this method is to measure the pressure changes that are created by the vortexes that are caused by the flow passing an object. It is usually measured with a quartz crystal. This kind of flow-meter is called a vortex-meter. Vortex created by the passage of an aircraft wing, revealed by coloured smoke A vortex is a spinning turbulent flow (or any spiral whirling motion) with closed streamlines. ...
Quartz is amongst one of the most common minerals in the Earths continental crust. ...
Measurement of the pressure within a pitot tube in the flowing fluid, or the cooling of a heated element by the passing fluid are two other methods that are used. These types of sensors are advantageous in that they are rugged, so not easily damaged in an extreme environment. A Pitot tube is a measuring instrument used to measure fluid flow. ...
A pitot tube is an L shaped tube which is also able to measure fluid flow. An advantage is that it does not disturb the flow as much as a venturi meter or an orifice plate would. It works by measuring the difference between the static pressure and the dynamic pressure.
Magnetic, ultrasound and coriolis flow meters 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 most common flowmeter a part from the mechanical flow meters, is the magnetic flow meter. A magnetic field is applied to the metering tube, which results in a potential difference proportional to the flow velocity perpendicular to the flux lines. The physical principle at work is electromagnetic induction. The magnetic flow meter requires a conducting fluid, e.g. water, and an electrical insulating pipe surface, e.g. a rubber lined steel tube. It has been suggested that Induction flowmeters be merged into this article or section. ...
It has been suggested that Magnetic field density be merged into this article or section. ...
Electromagnetic induction is the production of an electrical potential difference (or voltage) across a conductor situated in a changing magnetic flux. ...
Transit time ultrasound flowmeters work by measuring the time difference between an ultrasound pulse sent in the flow direction and an ultrasound pulse sent opposite the flow direction. This time difference is a measure for the speed of the fluid in the path of the ultrasound beam in terms of the speed of sound, c, in the fluid. By using the absolute transit time and the length between the ultrasound transducers, the current speed of sound is easily found. Ultrasonic flowmeters come in three different types: Transmission (contrapropagating transit time) flowmeters Reflection (Doppler) flowmeters Open-channel flowmeters // Transit Time flowmeters The most commonly used is the transit time flowmeter which is applied for clean or nearly clean fluids, as well as natural gas pipe systems. ...
A baby in its mothers womb, viewed in a sonogram Ultrasound is sound with a frequency greater than the upper limit of human hearing, approximately 20 kiloHertz/20,000 Hertz. ...
A baby in its mothers womb, viewed in a sonogram Ultrasound is sound with a frequency greater than the upper limit of human hearing, approximately 20 kiloHertz/20,000 Hertz. ...
The speed of sound c (from Latin celeritas, velocity) varies depending on the medium through which the sound waves pass. ...
Measurement of the doppler shift resulting in reflecting an ultrasonic beam off the flowing fluid is another recent, accurate innovation made possible by electronics. The Doppler effect is the apparent change in frequency or wavelength of a wave that is perceived by an observer moving relative to the source of the waves. ...
Ultrasound is sound with a frequency greater than the upper limit of human hearing, approximately 20 kilohertz. ...
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. Futhermore a direct measure of the density of the fluid is obtained. Coriolis measurement can very accurate and is very insensitive to variations in the medium that is measured, the same measurement tube can be used for measuring anything between Hydrogen gas and for instance Peanut butter without recalibration. A mass flow meter, also known as inertial flow meter and coriolis flow meter, is a device that measures how much liquid is flowing through a tube. ...
A mass flow meter, also known as inertial flow meter and coriolis flow meter, is a device that measures how much liquid is flowing through a tube. ...
General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ...
Peanut Butter in jar Peanut butter is a food product usually consisting of roasted and ground peanuts, usually salted and sometimes sweetened. ...
Calibration refers to the process of setting the magnitude of the output (or response) of a measuring instrument to the magnitude of the input property or attribute within specified accuracy and precision. ...
See also Mass flow rate is the movement of mass per time. ...
In fluid dynamics, the volumetric flow rate, also volume flow rate and rate of fluid flow, is the volume of fluid which passes through a given area per unit time. ...
A residential gas meter A gas meter is used to measure the flow of fuel gases such as natural gas and propane. ...
External links | 
Feeds |
Contact