## Flow Meters

The flow of both gas and liquid can be measure using different devices, for example, liquid flow meters. Flow measurement quantifies the rate at which fluid is moving. This movement may be linear, nonlinear, mass, or volumetric. Different flow meters are required for the varying substances and styles of measurement.

Some of the most common types of fluid flow meters include differential pressure flow meters, mass flow meters, open channel flow meters, positive displacement flow meters, and velocity flow meters.

The first type, the differential pressure flow meter, relies on Bernoulli’s Principle. This dynamic fluid principle states that a fluid flowing with no viscosity will simultaneously decrease in pressure or potential energy as a speed increase occurs. Examples of this type of flow meter include flow nozzles, orifice plates, and venturi tubes.

Next are mass flow meters, which measure the mass flow rate. The mass flow rate is a measurement of volume per unit time. Therefore, this measurement is taken by monitoring fluid as it travels through a pipe. The flow rate is measured as the mass of the fluid travels past a selected point per unit time. This flow rate might be a calculation of kilograms per second, for example. Two types of mass flow meters include thermal flow meters and Coriolis flowmeters.

Then there is open channel flow measurement. This type of flow measurement calculates the height of a fluid as it flows down an open channel and over a structure such as a weir or a flume. This measurement is then applied to the following theoretical formula to convert the findings into a flow rate. Q=KH^{X }, where Q = flow rate, K = a constant, H = the water level, and X = the exponent depending on which device is being used.

Positive displacement flow meters are mechanical and involve using rotors to measure flow. The fluid is displaced between the rotors and as this is occurring, rotations are being counted. These findings are converted into volume and flow rate by the flow meter. This type of flow meter can be used for a variety of nonabrasive substances including lubrication oils, animal and vegetable fat, printing ink, and more.

And lastly is the velocity flow meter, which calculates the speed of flow. This calculation is then incorporated with the flow area.

Flow meters are used to measure water usage for billing purposes, for example. They are also used to measure natural gas for billing. Efficiency can even be calculated from flow rates. The type of meter used must be taken into consideration depending on the purpose. The varying flow meters mentioned above are used to calculate the flow rate based on density, pressure, and viscosity.