Flow meters are perfect instruments for measuring and monitoring different types of flow rate measurements. From variable-area to single-use to magnetic to Coriolis flow meters, we are spoil for choice regarding water flow meter types. What differentiates these flow meters are accuracy levels, functionalities, and their prices. An example of a liquid flow meter whose price is on the higher end is an ultrasonic flow meter.
This type of flow switch used tubing to measure multiple flow rates accurately in a non-invasive way. If you are working with velocity and looking for an affordable flow meter with high accuracy levels, then single-use turbine-type sensors are ideal. The best flow meter for measuring high viscosity fluids is disposable ultrasonic for single glow use.
How to Select the Correct Water Flow Meter
Before buying any liquid flow meter type, you need to consider a few critical factors. Below are some of them:
- Media – The type of media refers to the condition of the fluid being measured, including the viscosity of the media and the particulates in the media. The media can either be slurry, gaseous, or liquid.
- Flow measurement type – Are you looking for a flow meter to measure volumetric flow, mass flow, or momentum (velocity)flow?
- Flow range refers to the flow rate reading range (the maximum and maximum flow rate a flow switch can handle).
- Media conditions – The user also needs to consider factors such as temperature and media pressure. These are the conditions of the fluid to be measure. You should also know whether these conditions will vary or remain constant.
- Environmental considerations – Does the application require special installation, ATEX zone installation, hygiene installation, or tamper proof readings?
- Accuracy levels – As the user, you also need to consider the accuracy levels required in the application.
An Overview of Liquid Flow Meter Types
Below is an overview of some of the most common using flow meter types base on different applications:
Single-use Turbine Flow Sensor
These types of flow meters are ideal for measuring applications that require high hygiene. This includes food, semiconductor fabrication where a CIP option is not optimal, bio pharma, etc. The type of flow sensors used here is invasive, which come into contact with fluids when measuring flow rate. Reusable flow sensors which don’t come into contact with the fluids can also be durable. For standard instruments, accuracy, sensor readability and workflow readability are given priority. Coriolis meter types are used when extremely high accuracies are needed(<1%) in single-use applications. These types of flow meters are also quite expensive. Most Coriolis flow meter types come in large sizes, track mass flow rate, and do not drop pressure. They also offer a very high turn down ratio. Coriolis flow meters can be used for measuring both gas and liquid substances.
Differential Flow Meter for Water
To determine velocity flow rate, these types of flow meters measure changes in pressure. An orifice that restricts flow or laminar flow element is used to evaluate pressure drop from the restriction. The flow rate is directly proportional to the upstream and downstream pressure drop. When ultra fast response time is necessary or when no moving parts are desired, these types of flow meters are ideal. You will find differential pressure flow meters in various applications measuring the input and output of the fuel. They are also used in aqua farms, water measurement testing, and chemical processing plants. In laboratories, these flow meter types are used for controlling and measuring the flow of gases in chromatography – the process of mixing and separating gases.
Gear meter types
This type of liquid flow meter uses oval counter-synchronized rotors or gears. The rotors are interlocked to allow them to rotate as the measured fluid passes through. A high-level accuracy is achieved by the oval gears which control the media passing through. The user can install this type of water flow switch in an aggressive environment thanks to its simple and rugged design. They are ideal types of flow meters for measuring fluids with high viscosity. Hydraulic applications that used very viscous liquids such as manufacturing, fuel or oil transfer. And pulp and paper industry utilize these flow meter types. The rotor gears are stainless, making them ideal for measuring and controlling light to heavy oils.
Magnetic meters/magmeters
Mag meters come in two distinctive designs. They include full-bore and insertion design styles. Magnetic fields are give by the coils are in these types of flow meters. The flow meter had electrodes found in the insertion probe or meter wall that produce an electric charge, and then the fluid passes through. The charge generated is proportional to the flow rate. The electrical content of water or other fluids being measured allows these types of flow meters to function. No moving parts are present in these types of flow meters. Intrusion into the stream is not necessary when using the full-bore type of magnetic flow meters. As advance types of flow meters, these are using in mining, pulp, paper manufacturing, chemical manufacturing, and petrochemical plants. They are not ideal when used with fluids that do not conduct electricity like deionized water.
Paddlewheel Meters
Fitted with rotating paddle wheels, oscillating disks (multi-jet types), and propellers, these types of liquid flow meters measure the velocity of the fluid. A pulse is generate by the rotating component in the liquid flow meter when passing through either an optical or magnetic sensor. At one point in the channel or pipe, the velocity is proportional to the frequency of the pulses. The two designs produce high accuracy flow measurement at a low cost. While other designs are hard to install, some insertion versions installation are easy. Paddle wheel flow meters are commonly used in rural areas for irrigation purposes, simple water measurement, aqua farms, and in-water & wastewater treatment. They are also ideal flow measurement instruments in oil and gas and utility applications.
Thermal Dispersion
Thermal dispersion types of flow meters have no moving parts. And they don’t measure fluids in volume but mass in gas measurement. They will measure gas substances very accurately, provided the gas is dry and has no particulates. The downside is that it is a fairly slow response time. A thermal dispersion liquid flow meter works with a side-stream flow of gas that utilizes capillary for direction. From one downstream to another, two external heater-sensor coils are uses by the capillary.
The gas flow carries heat to the downstream coil from the upstream coil. At each coil, what is measuring is the resultant temperature-dependent resistance differential. The instantaneous flow rate is linearly proportional to the gradient at the coils is linearly proportional to the instantaneous flow rate. Since they don’t have moving parts, they are also minimally invasive, thermal dispersion flow meters used in industries and filtration loading, instrument airlines. They can also control the flow rate in OEM applications and gas mixing.
Conclusion
To accurately measure water flow, it demands that the user purchases the right kind of liquid flow meter. We have given you critical information on how different types of flow meters work based on applications. We are glad that you read through it and hope to make the best decision when selecting a flow meter.
