A rotameter is an instrument that measures the flow of gases, liquids, and steam passing through a conical tube using a float. The more significant gap between the float and the line at the top enhances the massive flow passing through the meter. One should place the tube vertically to all its vertical orientation.
This article will discuss some types of rotameters, their working principles, applications, advantages, and disadvantages.
Types of rotameter
There are three main types of rotameter, namely;
1.Armored purge rotameter
2. Glass tube rotameter
3. Fanged armored rotameters
1.Armored purge rotameter
Armored purge rotameter measures the flow of fluids with higher pressure, low flow rates, and corrosive liquids in industrial and municipal setups. It purges the juices in the tube when the condition of the system is not well. It also analyzed gas systems and measurements where glass tube rotameters is not essential for safety purposes.
To that point, the buoy will go all over the Rotameters cylinder to the measure of liquid stream rate and the annular between the cylinder and buoy. At the point when the harmony is reached, then, at that point the buoy and stream rate development will have hit a steady situation in the cylinder.
2. Glass tube rotameter
A glass tube rotameter is a type of rotameter which controls the flow of liquids and gases. It brings out the most accurate results of low flow measurement. Glass tube rotameter is also suitable for fluid sampling applications.
Rota utilizes a buoy fitted inside a tapered cylinder to assist with measuring stream rate. The buoy is portable and goes all over unreservedly inside the cylinder. Space is found between the buoy and the cylinder, however it is bigger at the Rotameter’s top, which permits more liquid move through the meter. The container of the Rotameter is arranged upward in light of the fact that gravity works in vertical arrangement.
3. Fanged armored rotameter
Fanged armored rotameters gives accurate results on measurements at a high-pressure operation. It can measure the flow of opaque, non-conductive, and aggressive liquids in pharmaceutical, chemical, and petrochemical industries under high-pressure conditions.
Fanged armored rotameter may have transmitters, alarms, HART communications, and a configured digital display to enhance effective flow measurement. It is always available as a heat trace or metal tube meter for fluids under sensitive temperature.
Factors to consider when selecting a rotameter
Several factors you need to consider when selecting a rotameters are;
i)The size of the pipe for installation purposes.
Ii) The level of accuracy that is required.
iii) A need for back pressure during the flow.
iv) The conditions for the operations, i.e., the maximum and minimum flow rates and pressure and temperature procedures.
v) You should also consider whether the rotameters is for direct reading or the use of tables.
vi) The flow optional regulation valve
Applications of rotameter
i) Rotameter is used to monitor gas flow in plants and labs.
ii) Used to measure the flow of water in industry.
iii) Used in process industries.
iv) Used to monitor the loading of filtration.
In the event that the stream starts and the liquid gets into the dosing tube, a skimming impact makes the buoy lighter. Yet, the buoy has a higher thickness than the fluid, and the buoyancy impact will not be sufficient to raise the buoy.
How a rotameter works
Rotameters works by gauging the flow rate in a tube or pipe using a float that fits inside a conical box. The float has the ability to move-ups, downs, or even at the sides of the tube. The larger space between the float and the line in the rotameter top enhances the fluid flow through the meter.
The force used by the rotameters works under a vertical line; hence the orientation of the rotameter should also be vertical. The fluids to be measured ( liquids, gases, and steam) move from the rotameter bottom tube, travel around the float, and get out through the top.
The tube used on the measurement is vertically fixed with its small end at the rotameter bottom. If there is no flow in the rotameter, the float relaxes at the tube bottom, where the diameter inside the rotameter tube is the same as the float diameter.
In case of a fluid flow inside the dosing tube, the floating will be made simpler and lighter due to the floating effect, which cannot raise the float due to high fluid density. The float increases with the pressure falling and increases the gap between the float and the tube, thus providing the flow measurement results.
The floating force is higher than the hydraulic forces on the rotameters; hence the float goes up and down the rotameters tube up to a specific fluid flow rate and the gap between the float and the line.
The flow rate and the float are said to be in a stable position when the flow is at equilibrium. Annular opening between which is in the tube and the float increases with an increase in float movement at the rotameters tube.
An increase in the flowing area decreases the differential pressure on the float. Float affects the balances with the float weight at equilibrium due to the differential pressure on the float.
Advantages of rotameter
i)Rotameter helps to control the flow rate of corrosive fluids.
ii) Rotameter provides cost-effective metering for flow measurement.
iii) Rotameter is simple and easy to install and operate.
iv) It is easy to maintain a rotor since there is no standard requirement for repairing its parts.
v) It can measure the flow of slurry.
vi) There is a rotameter that is immune from viscosity float.
vii) Rotameter can measure fluids of small flow rates.
viii) One can change their uses for different operations since they are versatile.
ix) Rotameters have a linear scale over a variety of flow rates.
Disadvantages of rotameter
i)It is challenging to monitor measurements on opaque fluids.
ii) There can be breakage on the glass tubes.
iii) The rotameter does not work when it is not installed vertically.
iv) A specific minimum magnitude is required for the rotameter to function effectively.
Precautions for handling process
When handling rotameters, you need to observe the rules below for safety purposes.
i)Use the alcohol swabs in cleaning the outer glass layer.
ii) You should not set the rotameter at 0 when it is in operation to avoid obstruction of the pressurized airflow and the damage of the rotameter.
iii) Avoid parallel errors when undertaking the measurement readings.
iv) Handle the rotameters with a lot of care since it is made of glass; hence can break easily.
v) You should invert the rotameters upside down and move the float from the bottom when there is blockage of airflow due to the sticking of the flow. You can also use a gust of wind to remove the float in case of difficulty in inversion.
Conclusion
Rotameters, also known as the variable area flowmeters, are cost-effective, simple, and easy to maintain the type of flow meters essential in most industrial and municipal applications where it measures the volumetric or velocity flow of liquids and gases. It would help if you handled the instrument with a lot of care to avoid its breakage and get accurate results.
