A liquid flow meter is an instrument that one can use to measure the linear, non-linear volume and liquid or fluid mass flow. The apparatus controls the flow rate of liquids like water, chemicals, fuel, etc., in open channels or industrial pipes. The type of liquid flow metering one needs to use depends on the application to do or the area it is to be installed. Liquid flow meters technology has been essential to various industrial applications, commercial and residential activities internationally.
The liquid measuring Components make it easy for system operators to accurately measure the flow rate of liquids or fluids flowing through a pipe or tube.
How do liquid flow meters work?
Liquid flow meters work by measuring the speed of the liquid flowing in a pipe, leading to the rotation of the piston or paddle wheel where the volume or the flow rate of the flowing liquid is proportional to the speed of the rotating paddle. An increase in the rotation speed increases the amount of fluid flowing in the pipe and vice versa.
Factors to consider when choosing a liquid flow meter
There are various factors one needs to consider before purchasing and installing liquid flow metering for their applications. Some of them include;
i) The maintenance requirement of the liquid metering devices
ii) The cost of buying and installing the equipment.
iii) The longevity or the device’s lifetime.
iv) The accuracy factor, i.e., whether the device can provide highly accurate flow measurements.
v) The operating procedure of the device.
vi) The range of the liquid flow rate.
vi) The legal issues or requirements of the liquid flow metering.
Types of liquid flow meters
Liquid flow meters come in various types depending on the choice and application of the user. The most common types are;
1.Open channel Flowmeters
Open channel liquid flow meters measure the flow rate and density of the liquid flowing in any area such as rivers, streams, canals, etc. Measuring the depth of water brings out an instant flow rate measurement. Good examples of open channel flow meter types are; flume and Weir.
Applications of Open channel flow meter
i) Used in controlling or monitoring the spill.
ii) Used in irrigation schemes and channels.
iii) Used in measuring industrial products.
iv) Used in monitoring the sewer programs. i.e., both portable and non-portable ones
v) Used in treating wastewater.
i) One can use open channel liquid flow meters even in dangerous areas.
ii) One can measure and determine the flow rate with the correct equation easily.
iii) It has no moving parts, which can interfere with the liquid flow.
iv) Open channel flow meters have a long life operation.
v) It can measure liquids under corrosive media and also wastewater.
vi) It is simple to use and easy to maintain.
i) The flow of the liquid should be consistent for one to obtain the measurement.
ii) The dirt from the contaminated liquid collects at the bottom of the equipment, thus reducing the accuracy measurement level.
iii) The downstream and upstream blockages interfere with the liquid flowing in the pipe.
iv) There may be constraints in pipes that interfere with the liquid flow.
2. Differential pressure flow meters
Differential pressure flow meters are vital in measuring the liquid flow rate worldwide. The device determines the flow rate by measuring the differential pressure of the flowing liquids and finding the square root of the answer. Examples include; orifice plates, variable area meters, pilot tubes, etc.
Applications of Differential pressure flow meters
The various applications include; oil, chemical, power, and gas industries, where they measure the volume of liquids or gases at low and high temperatures.
Advantages of Differential pressure flow meters
i) Differential pressure flow meters are cheap to purchase and install.
ii) They are simple to use and easy to maintain due to the lack of moving parts.
iii) They can measure the flow rate of both liquids and gases.
iv) They can work with any pipe size.
v) They can measure liquids under low or high temperatures.
i) The square root relationship between the pressure head and the flow rate reduce the flow rate range.
ii) The pressure sensor determines the accuracy of the liquid.
iii) Differential pressure flow meter causes a high drop in pressure.
3. Positive displacement flow meters
Here, the rotors determine the liquid flow rate as they spin. The spinning effect displaces the flowing fluid in the pipe making their volume proportional to the spinning rotors. The electronic pulse transmitter calculates the rotation rounds and converts them to specific flow rate measurements.
Applications of Positive displacement pressure flow meters
i) Used to measure the flow of liquids in a mixer with two components.
ii) Used in the food and beverage industry to measure the flow of liquid containers.
iii) Used in water pipes to measure the volume of the flowing liquids.
iv) Used to measure acids and Viscous liquids in the chemical industry.
i) They can measure the flow rate of high viscous liquids.
ii) Positive displacement pressure flow meters have a long life and require fewer maintenance costs.
iii) They have a high level of accuracy which cannot be affected by downstream or upstream conditions.
iv) One can directly record the measurement in volume per minute time.
i) A sudden flow change can destroy the moving parts.
ii) They are heavy and expensive to purchase and install.
iii) Positive displacement pressure flow meters cannot measure the flow rate of abrasive and sticky liquids.
4. Mass flowmeters
Mass flow meters are types of liquid flow meters that measure the direct mass flow rate. It is used in wastewater, pharmaceutical, power, and mining industries. A good example is Coriolis.
i) Mass flow meters provide highly accurate results of mass flow.
ii) They do not require any inlet and outlet sections.
iii) Mass flow meters cannot be affected by temperatures, viscosity, or pressure variances.
i)The choices for materials are fewer.
ii) Gas inclusions can disrupt the measurements.
The article has discussed some of the types of liquid flow metering components used internationally. Ultrasonic and Velocity flow meters can also make a good choice for international liquid flow meter components.