Description
The flow meter is an instrument that is used widely in all industrial applications. A flow meter not only measures flow but also helps in getting other related parameters like pressure. This guides an engineer to get proper measurements of a media flow performance. The industry of flow meters is flourishing very rapidly and newer technologies are being adopted in them for efficient performance.
This is necessary because accordingly, industrial automation is flourishing with IoT and the need for a smart sensor with good connectivity options and able performance also increases. We will look at some latest flow meter technology developments in this post.
What is a flow meter?
If you are not sure what a flow meter is and how it functions, let us first understand it’s basic principles and working. A flow meter is in instrument which is used to measure the flow of a media like liquid, gas or vapor moving through a pipe, and then display it’s current value with the corresponding unit. It is installed in the pipeline and then calibrated according to the media properties, to give a correct value.
A flow is measured through many techniques. It can be done through the below methods:
- A paddle wheel inside which rotates as the flow increases or decreases. The wheel goes past a magnetic sensor in every rotation. The sensor pulses are determined by its frequency of on/off and is correspondingly converted to a flow value through internal calculations done by a processor.
- A position float that moves above or below according to the flow of the media. The movement of this float moves a corresponding scale of the flow.
- A magnetic flow meter measures the velocity of the fluid and uses Faraday’s formula – E (electrical voltage generated) = B(magnetic field strength) * L(length of the conductor) * V(velocity). Note that the media must be conductive to properly create an electromagnetic field.
- An ultrasonic flow meter sends rays inside the unit, due to which the ray bounces back depending on the volumetric flow inside. The time taken for the rays to travel back and forth determines the velocity of the fluid, which gives a corresponding measure of the flow.
Trends and innovation in flow meter technology:
1. Smart flow meter:
This is by far the most trending technology in flow meters. Apart from traditional analog signal outputs like 4-20 mA or 0-10V, smart flow meters have options for communication protocols like Ethernet, Modbus, BACnet, Fieldbus, etc. This enables them to smoothly connect with various controllers like PLC or DCS. The main advantage is that due to data in soft form, you can get an ample amount of information from a single meter, without the need for additional control signal wiring.
Also, many sensors nowadays are going one step ahead in having connectivity for IoT. An IoT module inside the sensor will require a good SIM card with a strong network, and the sensor will communicate directly on the cloud layer, sitting in any corner of the world. This enables very swift and reliable communication.
2. Improved processor performance inside the flow meter:
Every instrument has its own processor or a small chip inside for computing the calculations, and so is a flow meter. Due to advancements in processing capacities around the world, the same is being implemented in the meters. You can store more amount of data in the meter, allow faster communication speeds with the PLC, allow more accurate measurements of the media, allow complex calculations to happen for processing more amount of data, have advanced options in the graphics of the instrument for detailed troubleshooting, and is more flexible with different types of media which are not easy to explore like the ones used in hazardous areas.
3. Multitube flow meter:
This is another interesting concept for mass flow meters. A traditional mass flow meter uses a single tube or single entry which allows media flow. But sometimes, it can face issues in measurement due to vibrations, movements, or some other external disturbances. Due to this, the sensor will get confused as to whether the flow is coming from the actual media or coming from disturbances.
In this case, multiple tubes (typically 2-8 variants) are used where the media will enter from multiple points inside the sensor. Then, the differences between all the tubes are calculated and a net result or average is derived, which gives a very accurate answer of the flow. The tubes are inclined with each other at different angles to the sensor, for an exact answer.
4. Use of surface acoustic wave sensors in flow meter :
SAW or surface acoustic wave sensors are used extensively in ultrasonic-type flow meters. It uses multiple sensor locations for a whole setup of a single flow meter. An acoustic or sound signal is sent through the media and received at the other end. The time taken by the waves to travel determines the signal amplitude and frequency and is a direct correlation with the actual flow of the media.
This technology is greatly used in areas where clean media is required to flow, like wastewater, food and beverages, dairy, and semiconductors (because it can easily detect minute particles and bacteria in between due to the sound waves).
5. Self-cleaning flow meters :
In applications like sewage water treatment where access to flow meters for maintenance work can prove hazardous for the workers, a new technology is being adopted which is called a self-cleaning flow meter. Self-cleaning means the flow meter keeps itself clean by not allowing any debris or sludge to accumulate on its surface.
This is possible by the internal design of non-intrusive sensing elements. As the fluid or media flows between the tube walls, a scouring action happens which prevents the buildup of dirt or solid inside. So, minimum maintenance work is required in these types of meters.
6. Use of digital signal processing in flow meter :
DSP has been increasingly started to be used in flow meters. As the name suggests, signals are processed digitally by taking all the other factors into account like outside temperature, vibrations, moisture and other disturbances, and they are computed by complex DSP algorithms to give precise answers. As noise and other disturbances signals are eliminated in the calculations, you get a very correct measurement of the flow.
7. Self-diagnostics in flow meter :
Similar to the HART protocol in sensors where many advanced diagnostic features are provided for an instrument, flow meters also have self-diagnostic features implemented in them in recent times. There is no need for an additional sensor setup for monitoring, as the meter itself is capable of detecting faults inside it and displaying them on the screen. This is possible due to advanced processors used nowadays in the meters, which allow continuous assessment of their performance.
The global market of flow meters is increasing day by day, and as new sectors are discovered for their use, more and more technologies will emerge in the coming days. The future holds great promise and industry stakeholders can expect a great jump in their business due to the smart use of these types of sensors, which allow a safe, accurate, and efficient plant performance.
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