subject: How Different Meters Can Measure Flow [print this page] A number of flow measurement meters are on the market today. Primarily these types of meters are used to measure both liquid flow and gas. These measurements are used to measure mass or volumetric flow rates. As long as the materials density is known, the measurements can be converted between one another. The density of the material depends on a number of things.
In addition, the type of material also affects the density obtained from flow measurement meters as well. For instance, the density of gas is affected by its composition, temperature, as well as pressure. On the other hand, the density of liquid is not affected by the condition of the liquid. Overall, gas has the capacity to be placed under compression and will change volume under such circumstances.
The same applies when gas is cooled or heated. Therefore, gas volume measurements tend to vary regardless to whether they are similar in size, due to varying conditions. As for liquids, they tend to depend on how they are applied, as well as the industry they are used. This refers to the various units in relation to whether they are referred to gallons, liters and so forth.
A number of different flow measurement meters are currently out there. Among them are Laser Doppler flow measurement, mechanical flow meters, pressure-based meters, optical flow meters, open channel flow measurement, thermal mass flow meters, vortex flow meters, as well as electromagnetic, ultrasonic, and Coriolis flow meters. Within each type, there are a number of different kinds of meters.
Laser Doppler flow measurement
This type of meter allows for the measurement of blood flow through the use of a monochromatic laser diode. This is accomplished through inserting a laser probe into the tissue, then turning it on. Following this, the light disperses in a way so that some of it is reflected back to the probe in order to produce a signal. This signal then is processed in order to calculate the amount of flow within the tissue.
Modern flow meters
The modern meters include the electronic flow meters that incorporate newer technology, which corrects such things as temperature and pressure. This includes the Magnetic flow meters, Ultrasonic flow meters, and Coriolis flow meters.
Vortex flow meters
This type of flow measurement meter uses a bluff body, otherwise referred to as a shredder bar placed in the path of the fluid, which causes vortices to be created as the fluid passes by. A sensor downstream or atop of the shredder bar is responsible for measuring the frequency.
Thermal mass flow meters
With this type of product, a combination of temperature sensors and heated elements are usually used in order to measure the difference between the flowing heat transfer and static transfer of a fluid in order to get its density and specific heat.
Open channel flow measurement
The flow measurement meters within this area are those that measure acoustic Doppler velocimetry, dye testing, Area/velocity, and level to flow.
Optical flow meters
These products use laser light that is scattered by the passing of a particle in order to determine the flow rate.
Pressure-based meters
These meters use the Bermoulli's principle to determine the dynamic pressure. This occurs in a number of ways and includes the optical flow meters, multi-hole pressure probe, pitot tube, dall tube, orifice plate, and venture meter.
Mechanical flow meters
There are several kinds of mechanical products, such as the nutating disk meter, oval gear meter, pelton wheel, multiple jet meter, paddle wheel meter, single jet meter, woltmann meter, turbine flow meter, variable area meter, piston meter/rotary piston, as well as bucket-and-stopwatch.
