Complete Guide on flow meters and the different types of standard liquid flowmeter?

Devices used to estimate a selective liquid’s flow rate flowing in a pipe are called flow meters. The measurements can be done by either the mass flow rate or the volumetric flow rate, and the units in which it is estimated are kilograms per second and liters per second. The standard liquid flowmeter is used in many fields and has vital use. In the medicinal area, technical sector, like food processing, semiconductor fabrication, water control, etc. There are many kinds of flow meters, depending on the law that manages the use. 

Types of Flow Meters

Positive Displacement Flow Meters

These meters estimate the flow rate by measuring the amount of fluid passing through them. The actual method involves the liquid trap into a specific vessel, like knowing its flow rate. This is very much related to the case wherein we let water fill a bucket up to a particular decided level, after which it is left to flow out.

These flow meters can measure irregular flows or low flow rates and fit any liquid irrespective of its thickness or weight. Positive displacement flowmeters can be viewed as vital as they continue unchanged by the pipe’s turbulence.

Mass Flow Meters

These meters give the user an estimate of the flow rate by estimating the material mass running through them. This sort of weight led flow meter is typically used in chemical industries, wherein the weight-based analysis is vital to volumetric analysis. In thermal meters, the fluid flow cools off the probe preheated to a specific degree. The heat loss can be sensed and used to plan the rate at which the fluid will be running. On the other hand, Coriolis meters work on the Coriolis principle law in which the liquid flow by the vibrating tube creates a change in frequency or state shift or amplitude, which gives a ratio of its flow rate.

Differential Pressure Flow Meters

In differential pressure flow meters, the flow is estimated by measuring the fall in pressure as the fluid moves by the difficulties inserted into how it flows. As the pipe’s fluid flow rises, more falls in the compression pressure are registered by the meters. One can measure the flow rate as it will be equal to the pressure drop’s square root. 

Velocity Flow Meters

Velocity flow meters measure the fluid flow rate by estimating the fluid’s speed that flows by them. Here, the fluid’s speed directly correlates with its flow speed as they are directly equal to each other. In these meters, one can estimate the rate in a variety of ways in which the use of the turbine is also one depending on the way used to find out the speed; we have many kinds of velocity flow meters like Turbine flow meter, Vortex Shedding flow meter, and many more varieties. 

Flow rate measurement of liquids in dangerous situations, comprising those in mining, requires non-intrusive flow meters. SONAR flow meters, which are a kind of velocity flow meters, complete this type of need. Ultrasonic flow meters and electromagnetic flowmeters also make a part of velocity type flow meters.

Optical Flow Meters

Optical flow meters run on the optics law, i.e., they estimate the flow rate using light. Typically, they use a set-up comprising of a laser beam and photodetectors. Here, the shreds of the gas passing through the pipe divide the laser beam to provide pulses, which are chosen up by the customer. Then, the time within these signs is viewed as one would know the gap by which the photodetectors would be divided, which heads to the analysis of gas’s speed. These meters measure the particles’ exact speed forming the gases. They stay unchanged by the thermal situations and gas flow differences. Hence, they can provide highly accurate flow data even when the atmosphere is most unfavorable, say, for instance, when we have high temperature and force, high moisture, etc.

Open Channel Flow Meters

Open channel flow meters estimate the flow rate of a liquid whose flow path includes a free surface. Weir meters and Flume meters are the open channel flow meters that use secondary tools like bubblers or float to estimate the fluid’s base at an exact point. From this depth, the flow rate of the liquid can be taken. On the other hand, in a dye testing based open channel flow measurement case, a specific decided quantity of dye or salt is applied to change the attention of the running stream of the fluid. The resulting dilution gives a speed of the flow rate of the liquid. Next, it is to be seen that the accuracy with which the flow meters require to work is chosen by the form for which they are used. For case, when we want to control the flow of water by a pipe in our garden, it would be sufficient if we use a flow meter that has a lower accuracy than that which will be used when we require to control the flow of an alkali meant for a chemical process. One more factor that needs to be seen is that the flow meters can favorably perform the regulating actions when used in connection with the flow valves.


Choice of the suitable standard liquid Flow meters is vital to evade any loss due to misapplication, as there are many types of flow meters available. All the tools are not fit with all sorts of liquids; the thickness, impurities, material, and pipe size are analyzed.


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