The agricultural revolution gave birth to the flow measurement practices. It was essential to gauge and monitor the flow of water into the irrigated land. The second use of flow control measures was in water conservation. It led to the invention of many kinds of water flow meters. In the current world, you will find flowmeters in nearly all sectors of industries.
There are many types of flow meters. Each has a different working principle and area of use. In this write-up, we will look at the common types of flow meters and their uses.
Mechanical Flow Meters
You all know what the term mechanical means. These types of flow meters have some moving parts. They work when the fluid passing through a channel pushes some parts of the meter and sends a signal. These signals are converted to flow reading based on the calibration of the meter.
The mechanical flow meters can further be classified into four subtypes. They are:-
- Mass Flow Meters
- Positive Displacement Flow Meters
- Velocity flow Meters
- Differential Pressure Flow Meters.
Let us look into them and their uses.
Mass Flow Meters
These meters are weight oriented. They measure the mass of the fluid that passes through them at a unit time. The meters are in two types: the thermal mass flow meters and the Coriolis flowmeters.
Thermal mass flow meters are used in gas industries. Coriolis meters, on the other hand, deals with liquids. These meters are useful in industries that deal with hot fluids. In the case of a thermal mass flow meter, you use two electrodes to check the amount of heat that the gas loses when it travels a certain distance.
Positive Displacement Flow Meter
These flow meters are easy to use. They trap a known volume of fluid then release it. It repeats the process over and over. You get the flow rate by the number of times it releases the known volumes of fluid.
These flow meters are useful in wastewater management. It handles viscous fluids with high accuracy. Also, it does not require electricity to operate. Thus, it is very efficient. But you will need regular maintenance due to the moving parts.
Velocity Flow Meters
These meters were initially useful as open channel meters. As technology grew, a velocity meter for the closed channel was made. You can now get a meter that gauges the speed of fluid both as an intrusive or non-intrusive meter. It means that there are several subtypes of the velocity flow meter. They include;-
- Paddlewheel Flow Meters
- Vortex Flow Meters
- Turbine Flow Meters
- Ultrasonic Flow Meters
- Electromagnetic Flow Meter
Let us look into each type in detail.
Paddlewheel Flow Meter
These are the most common flow meters in the market. You’ll find them in a range of industries. They are insertion types of flow meters. They are easy to install and are suitable for fluids with a heat range below 100 degrees celsius.
You fix the rotor of the paddlewheel flow meter at a 90-degree angle to the flow rate. Also, it would help if you fit the meter on a section where the channel is straight. The inlet should be twice as long as the outlet. These meters are not suitable for corrosive and viscous fluids. Also, you can not use this sensor to gauge slurry.
Vortex Flow Meter
These meters have a barrier in the flow channel—the barrier causes whirling in the fluid. The sensor counts the number of vortices that pass a section in a second. The frequency of the vortices is converted into flow reading.
Vortex flow meters are among the most accurate flow meters in the market. The readings are independent of the property of a fluid. Yet, if the fluid moves at snail speed, it won’t be easy to create detectable vortices. You can apply these meters in an industry that requires fluids to flow in large pipes. It is good to avoid a vortex flowmeter on viscous fluids.
Turbine Flow Meter
Turbine flow meters work when a fluid rotates the turbine or a piston. It is among the cheapest flow meters you can get in the market. The uses of turbine flowmeters are stretched in many industries. But, these flow meters are not suitable for viscous fluids and dirty fluids. They are best when you are gauging clean fluids. These flow meters are the best to gauge fluids with low flow rates. Turbine flow meters need frequent maintenance since they have moving parts.
Ultrasonic Flow Meter
Just as the name suggests, they use ultrasound to detect a fluid flow within a channel. The meter sends signals upstream and downstream. Then, it checks the travel time and uses it to get the velocity of the fluid.
You can apply ultrasonic flow meters in many industries. First, they are non-intrusive. Hence, they are durable and easy to install. Also, they require minimal maintenance. They are highly accurate as they are not dependent on fluid properties. They are the most preferred types of flow meters in industries dealing with corrosive fluids.
Electromagnetic Flow Meter
Just as the name suggests, the meter uses electricity and magnetic fields to detect fluid velocity flow. In the electric section, it applies Faraday’s law. As the fluid flows through a magnetic field, it creates a charge. The voltage increases with the increase in the fluid velocity. The meter then converts the voltage into a flow rate.
These water flow meters have a low accuracy rate. Thus, they are not useful on custody transfer. Also, you cannot use them in pure water since the water lacks ions. The meters have different designs to fit chemical composition, potential abrasion, and flow velocity. Thus, consult your supplier when selecting electromagnetic flowmeters.
There are times your fluid properties vary from time to time. Since you can not keep changing the flow meter, you need one that caters to all those needs. A compound flow meter is perfect for the job. In most cases, the meter is a merger of two or more water flow meters. It has a section of the turbine flow meter for the high velocities. When the speed of the fluid reduces, it can change to positive displacement or multi-jet.
As you have seen, different water flow meters have different applications. You can get a meter depending on your fluid properties and accuracy needs. Consult a supplier to get the best meter for your use.