To get the correct measurement of velocity in fluids, you need to use the right instruments. Velocity flow meters have proved to be the best devices when calculating flow rate. Velocity flow meters are largely used because they provide accurate readings for measuring the velocity of fluids in any industrial process. Their sensitivity rate is high to flow conditions. However, to get an accurate flow rate when using these types of meters, the flow must be constant, and failure to have constant flow will lead to improper readings.
A multiple-bladed rotor that is perpendicular to the flow rate is mounted with a pipe. As the fluid passes this type of flow meter, the rotor inside it rotates. The number of rotations made is going to determine the flow rate. Although the turbine flow meter is quite economical, you will only use it with clean liquids. If you use these types of velocity flow meters with dirty fluids, they may end up getting clogged due to the accumulation of dirt. Once this happens, the flow meter will start giving out inaccurate readings.
Turbine Flow Meters
Turbine flow meters have magnetic pick-ups mounted on the turbine wheel, and the voltage pulses are recorded using a sensor. To get the flow reading, the voltage pulses need to be converted into flow rate. Turbine flow meters are largely used in different industrial applications, including natural gas measurement.
Turbine Flow Meter Benefits
Turbine flow meters offer several advantages when it comes to giving accurate velocity flow rates. Here are some of them:
- Low-pressure drop
- High accuracy levels
- Easy installation and maintenance
- Offers diverse flow rate readings
- The response time is very fast
Turbine Flow Meter Drawbacks
- It doesn’t work well with low fluid pressure
- A straight running pipe requires both upstream and downstream
Electromagnetic Flow Meter
Electromagnetic induction is the principle behind how these types of velocity flow meters work. This flow rate measurement principle works by creating voltage when a fluid that can conduct electricity passes through a magnetic field. The magnetic field in this type of measurement is created by the conductor and the energized coils found outside the pipe. To get the flow rate measurement, the produced charge needs to be calculated. Voltage detection is done using a pair of electrodes placed in the pipe wall, and a secondary element is used to measure the voltage. Electromagnetic types of flow meters are used to measure flow rate in individual water flow processes. For this flow meter to work when measuring flow rate, the fluid flowing through the pipe must be conductive. Since these types of velocity flow meters are mounted on the pipe walls, the fluid’s pressure will remain constant based on the length of the pipe. This is because there are no moving parts inside the pipe, destructing the flow.
The Benefits of Using an Electromagnetic Flow
The various advantages that electromagnetic flowmeters have to offer include:
- It provides constant readings regardless of the fluid’s density, pressure, viscosity, and temperature
- It makes an ideal instrument for measuring corrosive and dirty fluids
- Minimal pressure drop
- Less maintenance required
- Cost-Effective
- It is used to measure reverse and forward flows
- This type of flow meter works with all pipe sizes
Setbacks of Electromagnetic Flowmeter
- It only measures liquids and not gases
- The fluid measured should be conductive
- Electromagnetic noises can cause improper readings
- Partially-filled pipes won’t work well with this type of flow meter
- The operations will be hampered due to wet electrodes
- Straight pipes are required before and after the flow meter
- Greasy fluids can build up inside the pipe and cause inaccuracies
Vortex Flow Meter Types
This type of flow meter measures flows rate by taking readings and measurement of swirls or vortices when liquid passes through a bluff or an object. The ideal type of flows used in this type of flow meter should be open channels such as rivers, streams, or dams. It works when a bluff object is placed in the flow. Based on the flow’s velocity, vortices will be formed. The number of vortices formed is directly proportional to the flow rate.
The pressure differential is created when these vortices are formed. The flow meter has a flow sensor that senses and turns the vortices into signals. The vortex frequencies are directly proportional to the pulse voltage frequency.
The Benefits of Vortex Flow Meter Types
- It had no moving parts, which reduced regular maintenance cost
- Responses very fast
- Can measure several kinds of fluids, including slurries and chemicals
- You can use it with dirty or fluids that have particles since it has no moving parts
- It works well when measuring both gases and fluids
- Changes in flow pressure, density, temperature, and viscosity don’t affect its accuracy
Disadvantages of Vortex Flow Meter Types
- High-end cost
- It has to be mounted inline
- The flow must be turbulent
- It doesn’t work with slurries
Ultrasonic Flow Meter Types
The velocity flow rate in this type of flow meter is measured using ultrasonic waves. The working principle in this type of flow meter considers variation in transmitted and received sound waves. These readings will give you the flow rate. The transducer will transmit sound waves through the stream, and the returning sound waves will give information about the flow rate. The clump-up version of ultrasonic flow meters is used to measure flow rate in various meter sizes.
Ultrasonic Flow Meter Benefits
- Since they are non-invasive, the pressure drop is not experienced
- Works well even when changes occur in the flow stream
- Slurries are also measured using this flow meter
- Used in many industrial applications because it removes chemical and electrical noises
- It can measure fluid flowing in both directions
Conclusion
As we’ve seen, several types of flow meters are found in the market today for measuring flow rate velocity. If you want to get the best results, you must match the right type of flowmeter with the right industrial application. Always seek high-quality, accurate, and best flow measurement and measuring products from reputable vendors.
