There are several reasons why fluid temperature matters when choosing a flow meter.

Temperature effects the fluid viscosity. Usually, the viscosity decreases as temperature increases and vice versa. This may affect the measurement accuracy of your flow meter unless viscosity offsets are employed.  Please see application note, Why does fluid viscosity matter when selecting a flow meter for a detailed explanation.

When exceeding temperatures of +100^o C or -40^o C there are important safety factors to consider and it is suggested you speak to an applications engineer at the flow meter supplier about your specific application.  Important considerations are: product safety, component temperature limits, and potential personal safety or operating environment considerations.

At temperatures at or approaching 0^o C and at the ambient dew point, the buildup of ice on the flow meter is of concern.   Your application engineer can suggest ways to reduce or eliminate icing concerns.  At high temperatures the safety for personnel may be a consideration and protective shielding may be needed.

Proteus Industries has years of experience producing flow meters for extreme temperatures and in designing protective measures for flow meters operating at extreme temperatures.

An instrument, which measures the volumetric flow rate of the fluid running through a closed conduit, is called a rotameter. The device consists of a float and a tube. Being a kind of a variable-area meter, it analyzes the flow rate by the upward and downward motion of the float in the tapered tube and the measurement provided by the flow meter is directly proportional to the area of flow and the flow rate.

 

Principle Involved in the Operation of the Rotameter

 

Now the question is how to read a rotameter? Rotameter is the most accepted industrial flow meter, which works based on the principle of gravity and variable area. The flow rate increases and decreases the height of the float, which accordingly adjusts the passage of the fluid flow and consequently, the total area between the float and the wall of the tube. Equilibrium is reached when the upward force created by the flowing fluid balances the descending force exerted by the mass of the float, hence maintaining a stable position of the float. The unit of the measurement is in liters or gallons per minute.

 

How to read a Rotameter:

 

Along with the float and tube, a rotameter may come equipped with an adjustment knob, which enables the user to set the flow rate according to their requirement. Let’s summarize the procedure for reading a rotameter:

 

• Connecting the rotameter with the fluid flowing source, to initiate the process.
• The float starts to swim in the middle of the tapered pipe due to the velocity of the fluid.
• The side of the meter has a scale. The lower and upper level of the float is to be measured by that scale, which gives the flow rate.

 

So, this is all about how to read a rotameter, which works in the combined effects of the velocity of the fluid, the gravity of the float, and annular area of the meter.

A liquid flow indicator is used to determine the direction and velocity of the liquid flow. This indicator can be used to detect any leakage, low liquid flow rate, leading to the reduction of water bills and elevation of the efficiency of any system. The accurate liquid flow indicator measures the bidirectional movement of the fluid flow in the smallest unit. The selection of the correct flow meter doesn’t only depend on the flow rate, but various criteria, including technical parameters that have to be analyzed before the selection to obtain the desired result. The indicators work in both conductive as well as non-conductive fluid. The conductive fluid includes electrolytes, liquid metals, saline water, etc. and non-conductive fluid includes heptanes, benzene, toluene, etc.

 

The function of the Flow Indicator:

 

An accurate liquid flow meter shows the low to moderate flow rate of liquid with minimal back pressure and enhanced accuracy. The flow indicator comprises a cover and a body. Both the halves are fitted around an impeller, leading to the rotation of the impeller when the fluid flows. The velocity of the fluid flowing in the pipe can be increased by using a tapered inlet nozzle. This not only helps the impeller to move freely but also decreases the back pressure. The revolution of the impeller is analyzed electronically and the plenum is used on the inlet and outlet valve to create a platform of consistent pressure irrespective of conduit location and direction. To increase the precision of the flow indicator, the size of the impeller is kept equivalent to the chamber, so that no liquid is able to pass through it without recording its velocity. The blades of the impeller are impregnated with magnets to create an electromagnetic flux when the impeller revolves. A wire coil with an iron core or a Hall-Effect Sensor is used to enhance and detect the magnetic flux generated by the revolving magnet. A microprocessor that has been pre-programmed is installed in the indicator, which records the response of the coil or HE sensor and calculates the appropriate information of the liquid flow and also records the time since the last restore.

 

Selection & Applications of the Flow Indicator:

 

The selection of the indicators should be done on the basis of the few factors which contribute to its maintenance, spare parts availability, installation cost, calibration and failure records. The flow meter should be chosen after the selection of a competent indicator. As the accurate liquid flow indicator will make sure you get a precise result. The re-personification of the indicator can be done with the changing demand, keeping the basic principle of the indicator intact. The use of flow meter indicator in partnership with the water filtration is widely used with no restrictions, as long as the fluid is compatible with the flow meter. The indicator can be used in various fields such as pharmaceutical and chemical processing, food processing, farming, machine tools and robotics application and in any field where the liquid flow needs to be measured.

Calibration is the comparative study made between the readings of a device and a corresponding standard under consideration. Liquid flow meters are devices that have a wide application in the industrial world. Hence, it is important to calibrate such devices so that an accurate and a precise reading are eventually obtained. Thus, this article will tell you that the importance of liquid flow meter calibration.

• Fluid Properties: The flow meters are interactive in nature. This means that the flow meter would interact with the liquid under consideration to establish a valid reading. Now, it is to be noted that the compatibility of the flow meter and the pipeline plays an essential role that gets reflected during calibration. No matter how scientific the method is, the system and the pipeline have to undergo certain changes during the installation process. This leads to the requirement of calibration to establish harmony between them.

• Flow Profile: In simple words, flow profile is the actual flow of the liquid under consideration in the pipeline. No matter how straight the pipe is, you cannot expect the liquid to flow in an even manner. There will be the presence of bends, valves, and viscosity that will alter the velocity gradient of the fluid. In the method of calibration, all these anomalies are kept under consideration before calibrating the liquid flow meter. This helps in obtaining a generalized reading despite the constant changes that actually take place in the velocity gradient of the fluid.

• Traceability, Accuracy, and Uncertainty: Calibrated reading, as mentioned previously, is a comparative study. Therefore, this method actually establishes the relation that the standard of measurement and the quantity to be measured belong to the same category of physical quantities and units. Traceability is the process of comparing a measurement to an unbroken chain of similar national and international standards. Accuracy is the measure of how close the obtained reading is to the true measurement. Besides, the uncertainty is basically a non-negative parameter which features the dispersion of the quantity values attributed to the measurand based on the certain standard information. To establish these three parameters, it is important to calibrate the liquid flow meter. Otherwise, it would not be possible to obtain the specified results.

• Performance Indicators: In order to enable the performance indicators to provide the suitable and the desirable reading, it is important to calibrate the system so that the resultant output is truly satisfactory.

Hence, it can be perceived that the liquid flow meter calibration is an important task for understanding the flow of liquid and taking the correct readings. If the task of obtaining the required measurements remains incomplete then, the entire system would become non-functional. Therefore, it is absolutely necessary to calibrate the device for securing optimum results.

Digital flow meters are of immense importance in Industry. This is an instrument that forms that the basis of many industrial processes that are necessary for the upliftment of both technology and lifestyle. Therefore, it is important to be very cautious while choosing suitable digital flow meters for liquids because of their wide and significant usage. Thus, in this article, you will be informed about some of the key factors that you should keep in mind while ordering an instrument belonging to this segment.

• Compatibility: In the majority of the cases, complaints are lodged regarding the unsatisfactory functioning of the digital flow meters. This often occurs due to the incorrect selection of meters. So, the selection of meters needs to be made on the basis of compatibility for securing the optimum performance, and to ensure accurate readings.

• The Range of Flow: Range of Flow can be defined as the ratio of the lowest rate of pumping to the highest rate of pumping for a system. In order to set up a meter and a system together, the range of the system has to be kept in mind. Otherwise, the readings obtained may be incorrect and, in the worst cases, the digital flow meter itself might get damaged.

• The Size of the Pipe: The size of the pipe is an essential factor that governs the kind of digital flow meter that has to be bought. For a pipe which has a small diameter, a small meter is sufficient. This is a very good option as the price of the meter is reasonable in this case. However, if the diameter of the pipe is larger than necessary, a highly priced and a rarely available meter could compromise the functionality of the entire system.

• Accuracy: Before buying the digital flow meter for liquids, you have to ascertain the range of accuracy of the device required for your application. In most applications the error should vary no more than – 5% and + 5%. Hence, proper checking has to be done before the installation of the device.

• Maintenance: This is the most important factor that you have to keep in mind before buying a digital flow meter. You have to thoroughly search out whether or not the company from which you are going to buy the meter provides after-sales maintenance. As this is a “gadget”, you have to keep this in mind that it may not always work perfectly. Sometimes, the calibration itself might get distorted. Therefore, it is essential that the company has the provision of sending skilled personnel for regular diagnosis so that your work is not hindered. (We don’t provide this so do we want to say it?)

Thus, it can be understood that digital flow meters for liquids are significant systems that are used regularly for research. They also have wide application in industry because of which these products are in such a huge demand. Therefore, before buying this essential product, it is advisable that the aforesaid suggestions should be followed dutifully to ensure a right choice. And, if the right choice is made, the system will surely deliver the desired output with accuracy and precision.

A vortex type flow meter is a velocity type flow meter which tends to follow a linear relationship with the volume flow rate. This flow meter is not like differential pressure type flow meters, as there no square-root relationship is found in these apparatus. Hence, their acceptability is better as compared to other flow meters. The vortex type flow meter is a flow measurement device used for measuring the flow velocity of gases and liquids where the introduction of moving part induces the problem. They are available in the commercial brand, brass or all-plastic construction. These liquid flow measurement devices are equally adapted for domestic and commercial applications. They calibrate, decide, and evaluate the right amount or flow of liquid. It also assists the progress of the proper management of liquid and identifies if there is any misuse or leakage that leads to wastage.

 

The Applications of the Flow Meter:

 

The vortex type flow meter is utilized to measure the flow and measure of liquid in a certain container like pipelines, tanks, industry-usable chambers, and natural sources are available with a distinct mechanism and technical features. Different operational modes and technicality depend on the areas of application, functional importance and nature of liquid, which is assessed by them. Velocity flow measurement meters are widely used in the commercial fields like Food and Beverage, Petrochemical Industries, Water Research, Fire Rescue Operation, Chemical Industries, Pharmaceutical Industries, Oil Industries, Fuel Industries, Submarine Industry, Paints, Grease, and Coating industry.

 

 Principle Involved In the Functionality of the Flow Meters:

 

The Vortex type flow meters function under the vortex shedding principle. The vortex shedding frequency is the oscillating frequency of the vortex shedding. This frequency is directly proportional to the velocity of the liquid flowing in the pipe, and to the volumetric flow rate. Fluid properties such as density, viscosity, conductivity, etc., don’t affect the mechanism. Only the flow must be turbulent for vortex shedding to occur. The basic relationship between vortex shedding frequency and fluid velocity is:

 

 St = f (d/V)

 

Where St is the Strouhal number which is a dimensionless aligning factor used to differentiate a variety of bluff bodies.

 

F = vortex shedding periodicity, d = width of bluff body, V = average fluid acceleration.

 

It is ideal for budget applications. Industrial vortex meters require appropriate sizing for a particular application. It measures flow of liquids, gas, and steam by detecting the frequency at which vortices are alternately shed from a bluff body. 

 

Components & Types of Vortex Flow Meter:

 

There are few limits to be considered before doing selection of the flow meter. Few of them are- what fluid is being measured, the range of flow rate and pressure, fluid temperature and density, pipe size, viscosity range, etc. Smart vortex meters supply digital output signal containing data apart from flow rate. The microprocessor in the flow meter can inevitably correct the insufficient straight pipe conditions, the differences between the bore diameter and mating pipe. Intelligent transmitters can start testing routines to find problems with both the meter and the application. Some flow meters can detect mass flow. It can measure both vortex frequency and pulse strength. From it, the density of the processed fluid can be determined. Another type of flow meter is equipped with multiple sensors to detect vortex frequency as well as temperature and pressure of the resultant fluid.