What is a flow meter？

Flow meters are devices that can be used to measure the amount of liquid, or gas which passes through it. It is an instrument which is used to conduct the flow instrument measurement. The flow rate of liquid and gases must be measured accurately for the better quality of the industrial process. Accurate measurement of gases is needed for the industrial process and it also does the control of flow rate. Flow meters measure the flow by two methods, some flow meters measure the flow as the amount of the liquid passes through the flowmeter during a period of time. While other flow meters measure the flow by measuring the total amount of fluid that has passed through the flow meter.

How does a flow meter work

Flowmeter consists of devices such as transducer and transmitter, the transducer will sense the fluid that passes through the primary device. The transmitter will receive a signal from the transducer, so the transducer changes this signal into a usable flow signal. So a flow meter can be considered as the combination of these physical devices.

What are the factors that affect a flow meter selection

Pipe size and accuracy

Repeatability and cost

The phase of the fluid-like gas, liquid, steam

Flow conditions and flow range, flow conditions like clean, dirty, abrasive, viscous will affect

Process conditions like pressure and temperature

What are the types of flow meter

Flow meters can be classified into differential pressure meters, variable area meter, positive displacement meters, magnetic, turbine, advantages of ultrasonic flow meter, vortex, and Coriolis. In differential pressure meters a restriction is used to create a pressure drop. So the flow rate can be determined by measuring the pressure drop across the restriction. In positive displacement meters, the measuring process takes place by precision-fitted rotors as flow measuring elements.

Ultrasonic flow meters

Ultrasonic waves can propagate through any substances like solid, liquid, gases and this property of the wave is utilized to measure the fluid flow in a pipe the ultrasonic signal is sent to the pipe at an angle, and the time taken for the signal to reach from one side to another is measured. The difference between the transit time across the pipe and that of the signal traveling in the reverse direction is proportional to the flow rate.

Vortex flowmeter

This flow meter is also known as oscillatory flow meters, it utilizes the natural phenomena when a liquid is allowed to flow in a bluff object. The frequency of the vortex shedding is directly proportional to the velocity of the liquid flowing through the r, this meter is widely used to measure the steam flow.

Magnetic flow meter

Magnetic flow meter depended on faraday’s law of electromagnetic induction, so it states that voltage will be induced when a conductor moves through a magnetic field. The liquid acts as the conductor and the magnetic field are created by energized coils outside the flow tube. The voltage produced is directly proportional to the flow rate, two electrodes are attached to the pipe wall to detect the voltage and it is measured by a secondary element. These flow meters can measure corrosive liquids and slurries